Add initial implementation of importlib. See the NOTES files for what is

planned for the package.

There are no docs yet, but they are coming once the API for the first new
function, importlib.import_module() is finalized.

Lib/importlib/NOTES

@@ -0,0 +1,78 @@
+to do
+/////
+
+* Write importlib.__import__
+
+* Document
+    + Package.
+    + import_module
+    + __import__
+
+* Create reasonable base tests that all finders and loaders must pass so
+  that various implementations can just subclass as needed.
+
+* Expose built-in and frozen importers.
+    + Make staticmethods so that class can be used directly.
+
+* Reorganize support code.
+    + Separate general support code and importer-specific (e.g. source) support
+      code.
+        - Create support modules for each subdirectory (as needed).
+    + Add a file loader mock that returns monotonically increasing mtime.
+        - Use in source/test_reload.
+        - Use in source/test_load_module_mixed.
+
+* API simplification?
+    + read_source -> get_data/source_path
+    + read_bytecode -> get_data/bytecode_path
+    + write_bytecode -> complete set of bytes for bytecode instead of
+      individual arguments.
+
+* Implement PEP 302 protocol for loaders (should just be a matter of testing).
+    + Built-in.
+    + Frozen.
+    + Extension.
+    + Source/bytecode.
+
+* Create meta_path importer for sys.path.
+
+* OPTIMIZE!
+  + Write benchmark suite.
+  + Fast path common cases.
+    - Absolute name from sys.path.
+    - Relative name from sys.path.
+
+* Public API (w/ docs!)
+  + abc
+      - Finder
+        * find_module
+      - Loader
+        * load_module
+      - ResourceLoader(Loader)
+        * get_data
+      - InspectLoader(Loader)
+        * is_package
+        * get_code
+        * get_source
+      - (?) SourceLoader(ResourceLoader)
+        * source_path
+        * bytecode_path
+        * write_bytecode
+  + util
+      - get_module decorator (new name)
+      - check_name decorator (new name)
+  + hooks (?)
+      - (?) Chained path hook/finder
+      - BuiltinImporter
+      - FrozenImporter
+      - (?) FileFinder
+      - Extensions importers
+          * ExtensionFinder
+          * (?) Loader
+      - Source/bytecode importers
+          * SourceFinder
+          * (?) Loader
+  + __init__
+      - __import__
+      - import_module (backport to 2.7)
+      - resolve_name (backport to 2.7)

Lib/importlib/__init__.py

@@ -0,0 +1,133 @@
+"""A pure Python implementation of import.
+
+References on import:
+
+    * Language reference
+          http://docs.python.org/ref/import.html
+    * __import__ function
+          http://docs.python.org/lib/built-in-funcs.html
+    * Packages
+          http://www.python.org/doc/essays/packages.html
+    * PEP 235: Import on Case-Insensitive Platforms
+          http://www.python.org/dev/peps/pep-0235
+    * PEP 275: Import Modules from Zip Archives
+          http://www.python.org/dev/peps/pep-0273
+    * PEP 302: New Import Hooks
+          http://www.python.org/dev/peps/pep-0302/
+    * PEP 328: Imports: Multi-line and Absolute/Relative
+          http://www.python.org/dev/peps/pep-0328
+
+"""
+from . import _bootstrap
+
+# XXX Temporary functions that should eventually be removed.
+import os
+import re
+import tokenize
+
+def _set__import__():
+    """Set __import__ to an instance of Import."""
+    global original__import__
+    original__import__ = __import__
+    __builtins__['__import__'] = Import()
+
+
+def _reset__import__():
+    """Set __import__ back to the original implementation (assumes
+    _set__import__ was called previously)."""
+    __builtins__['__import__'] = original__import__
+
+
+def _case_ok(directory, check):
+    """Check if the directory contains something matching 'check'.
+
+    No check is done if the file/directory exists or not.
+
+    """
+    if 'PYTHONCASEOK' in os.environ:
+        return True
+    elif check in os.listdir(directory):
+        return True
+    return False
+
+
+def _w_long(x):
+    """Convert a 32-bit integer to little-endian.
+
+    XXX Temporary until marshal's long functions are exposed.
+
+    """
+    x = int(x)
+    int_bytes = []
+    int_bytes.append(x & 0xFF)
+    int_bytes.append((x >> 8) & 0xFF)
+    int_bytes.append((x >> 16) & 0xFF)
+    int_bytes.append((x >> 24) & 0xFF)
+    return bytearray(int_bytes)
+
+
+def _r_long(int_bytes):
+    """Convert 4 bytes in little-endian to an integer.
+
+    XXX Temporary until marshal's long function are exposed.
+
+    """
+    x = int_bytes[0]
+    x |= int_bytes[1] << 8
+    x |= int_bytes[2] << 16
+    x |= int_bytes[3] << 24
+    return x
+
+
+def import_module(name, package=None):
+    """Import a module.
+
+    The 'package' argument is used to resolve relative import names. Typically
+    this is the __package__ attribute of the module making the function call.
+
+    """
+    if name.startswith('.'):
+        if not package:
+            raise TypeError("relative imports require the 'package' argument")
+        level = 0
+        for character in name:
+            if character != '.':
+                break
+            level += 1
+        name = Import._resolve_name(name[level:], package, level)
+    __import__(name)
+    return sys.modules[name]
+
+
+
+# Required built-in modules.
+try:
+    import posix as _os
+except ImportError:
+    try:
+        import nt as _os
+    except ImportError:
+        try:
+            import os2 as _os
+        except ImportError:
+            raise ImportError('posix, nt, or os2 module required for importlib')
+_bootstrap._os = _os
+import imp, sys, marshal, errno, _fileio
+_bootstrap.imp = imp
+_bootstrap.sys = sys
+_bootstrap.marshal = marshal
+_bootstrap.errno = errno
+_bootstrap._fileio = _fileio
+import _warnings
+_bootstrap._warnings = _warnings
+
+
+from os import sep
+# For os.path.join replacement; pull from Include/osdefs.h:SEP .
+_bootstrap.path_sep = sep
+
+_bootstrap._case_ok = _case_ok
+marshal._w_long = _w_long
+marshal._r_long = _r_long
+
+from ._bootstrap import *

Lib/importlib/_bootstrap.py

@@ -0,0 +1,997 @@
+"""Core implementation of import.
+
+This module is NOT meant to be directly imported! It has been designed such
+that it can be bootstrapped into Python as the implementation of import. As
+such it requires the injection of specific modules and attributes in order to
+work. One should use importlib as the public-facing version of this module.
+
+"""
+
+# Injected modules are '_warnings', 'imp', 'sys', 'marshal', 'errno', and '_os'
+# (a.k.a. 'posix', 'nt' or 'os2').
+# Injected attribute is path_sep.
+#
+# When editing this code be aware that code executed at import time CANNOT
+# reference any injected objects! This includes not only global code but also
+# anything specified at the class level.
+
+
+# XXX Could also expose Modules/getpath.c:joinpath()
+def _path_join(*args):
+    """Replacement for os.path.join."""
+    return path_sep.join(x[:-len(path_sep)] if x.endswith(path_sep) else x
+                            for x in args)
+
+
+def _path_exists(path):
+    """Replacement for os.path.exists."""
+    try:
+        _os.stat(path)
+    except OSError:
+        return False
+    else:
+        return True
+
+
+def _path_is_mode_type(path, mode):
+    """Test whether the path is the specified mode type."""
+    try:
+        stat_info = _os.stat(path)
+    except OSError:
+        return False
+    return (stat_info.st_mode & 0o170000) == mode
+
+
+# XXX Could also expose Modules/getpath.c:isfile()
+def _path_isfile(path):
+    """Replacement for os.path.isfile."""
+    return _path_is_mode_type(path, 0o100000)
+
+
+# XXX Could also expose Modules/getpath.c:isdir()
+def _path_isdir(path):
+    """Replacement for os.path.isdir."""
+    return _path_is_mode_type(path, 0o040000)
+
+
+def _path_without_ext(path, ext_type):
+    """Replacement for os.path.splitext()[0]."""
+    for suffix in suffix_list(ext_type):
+        if path.endswith(suffix):
+            return path[:-len(suffix)]
+    else:
+        raise ValueError("path is not of the specified type")
+
+
+def _path_absolute(path):
+    """Replacement for os.path.abspath."""
+    if not path:
+        path = _os.getcwd()
+    try:
+        return _os._getfullpathname(path)
+    except AttributeError:
+        if path.startswith('/'):
+            return path
+        else:
+            return _path_join(_os.getcwd(), path)
+
+
+class closing:
+
+    """Simple replacement for contextlib.closing."""
+
+    def __init__(self, obj):
+        self.obj = obj
+
+    def __enter__(self):
+        return self.obj
+
+    def __exit__(self, *args):
+        self.obj.close()
+
+
+class _BuiltinFrozenBaseLoader(object):
+
+    """Base class for meta_path loaders for built-in and frozen modules.
+
+    Subclasses must implement:
+
+        * _find(fullname:str) -> bool
+            Finder which returns whether the class can handle the module.
+
+        * _load(fullname:str) -> module
+            Loader which returns the loaded module. The check for sys.modules
+            does not need to be handled by this method.
+
+        * type_:str
+            Name of the type of module being handled. Used in error messages.
+
+    """
+
+    def find_module(self, fullname, path=None):
+        """Find a module."""
+        if not self._find(fullname):
+            return None
+        return self
+
+    def load_module(self, fullname):
+        """Load a module."""
+        try:
+            return sys.modules[fullname]
+        except KeyError:
+            pass
+        mod = self._load(fullname)
+        if not mod:
+            raise ImportError("expected {0} module not "
+                                "loaded".format(self.type_))
+        return mod
+
+
+class BuiltinImporter(_BuiltinFrozenBaseLoader):
+
+    """Meta path loader for built-in modules."""
+
+    type_ = "built-in"
+
+    def __init__(self):
+        """Set the methods needed by the class.
+
+        Cannot be set at the class level because the imp module is not
+        necessarily injected until after the class is created.
+
+        """
+        self._find = imp.is_builtin
+        self._load = imp.init_builtin
+
+    def find_module(self, fullname, path=None):
+        """Try to find the built-in module.
+
+        If 'path' is ever specified then the search is considered a failure.
+
+        """
+        if path is not None:
+            return None
+        return super().find_module(fullname, path)
+
+    def load_module(self, fullname):
+        """Load a built-in module."""
+        if fullname not in sys.builtin_module_names:
+            raise ImportError("{0} is not a built-in module".format(fullname))
+        return super().load_module(fullname)
+
+
+class FrozenImporter(_BuiltinFrozenBaseLoader):
+
+    """Meta path class for importing frozen modules."""
+
+    type_ = 'frozen'
+
+    def __init__(self):
+        """Specify the methods needed by the superclass.
+
+        Because imp may not be injected until after class creation these
+        methods cannot be set at the class level.
+
+        """
+        self._find = imp.is_frozen
+        self._load = imp.init_frozen
+
+    def load_module(self, fullname):
+        """Load a frozen module."""
+        if not self.find_module(fullname):
+            raise ImportError("{0} is not a frozen module".format(fullname))
+        return super().load_module(fullname)
+
+
+class ChainedImporter(object):
+
+    """Finder that sequentially calls other finders."""
+
+    def __init__(self, *importers):
+        self._importers = importers
+
+    def find_module(self, fullname, path=None):
+        for importer in self._importers:
+            result = importer.find_module(fullname, path)
+            if result:
+                return result
+        else:
+            return None
+
+
+# XXX Don't make filesystem-specific and instead make generic for any path
+#     hooks.
+def chaining_fs_path_hook(*path_hooks):
+    """Create a closure which calls the path hooks sequentially looking for
+    which path hooks can handle a path entry.
+
+
+    Passed-in path hooks work as any other path hooks, raising ImportError if
+    they cannot handle the path, otherwise returning a finder.
+
+    """
+    def chained_fs_path_hook(path_entry):
+        """Closure which sees which of the captured path hooks can handle the
+        path entry."""
+        absolute_path = _path_absolute(path_entry)
+        if not _path_isdir(absolute_path):
+            raise ImportError("only directories are supported")
+        accepted = []
+        for path_hook in path_hooks:
+            try:
+                accepted.append(path_hook(absolute_path))
+            except ImportError:
+                continue
+        if not accepted:
+            raise ImportError("no path hooks could handle %s" % path_entry)
+        return ChainedImporter(*accepted)
+    return chained_fs_path_hook
+
+
+def check_name(method):
+    """Decorator to verify that the module being requested matches the one the
+    loader can handle.
+
+    The first argument (self) must define _name which the second argument is
+    comapred against. If the comparison fails then ImportError is raised.
+
+    """
+    def inner(self, name, *args, **kwargs):
+        if self._name != name:
+            raise ImportError("loader cannot handle %s" % name)
+        return method(self, name, *args, **kwargs)
+    inner.__name__ = method.__name__
+    inner.__doc__ = method.__doc__
+    inner.__dict__.update(method.__dict__)
+    return inner
+
+
+class _ExtensionFileLoader(object):
+
+    """Loader for extension modules.
+
+    The constructor is designed to work with FileImporter.
+
+    """
+
+    def __init__(self, name, path, is_pkg):
+        """Initialize the loader.
+
+        If is_pkg is True then an exception is raised as extension modules
+        cannot be the __init__ module for an extension module.
+
+        """
+        self._name = name
+        self._path = path
+        if is_pkg:
+            raise ValueError("extension modules cannot be packages")
+
+    @check_name
+    def load_module(self, fullname):
+        """Load an extension module."""
+        assert self._name == fullname
+        try:
+            module = imp.load_dynamic(fullname, self._path)
+            module.__loader__ = self
+            return module
+        except:
+            # If an error occurred, don't leave a partially initialized module.
+            if fullname in sys.modules:
+                del sys.modules[fullname]
+            raise
+
+    @check_name
+    def is_package(self, fullname):
+        """Return False as an extension module can never be a package."""
+        return False
+
+    @check_name
+    def get_code(self, fullname):
+        """Return None as an extension module cannot create a code object."""
+        return None
+
+    @check_name
+    def get_source(self, fullname):
+        """Return None as extension modules have no source code."""
+        return None
+
+
+def suffix_list(suffix_type):
+    """Return a list of file suffixes based on the imp file type."""
+    return [suffix[0] for suffix in imp.get_suffixes()
+            if suffix[2] == suffix_type]
+
+
+# XXX Need a better name.
+def get_module(fxn):
+    """Decorator to handle selecting the proper module for load_module
+    implementations.
+
+    Decorated modules are passed the module to use instead of the module name.
+    The module is either from sys.modules if it already exists (for reloading)
+    or is a new module which has __name__ set. If any exception is raised by
+    the decorated method then __loader__, __name__, __file__, and __path__ are
+    all restored on the module to their original values.
+
+    """
+    def decorated(self, fullname):
+        module = sys.modules.get(fullname)
+        is_reload = bool(module)
+        if not is_reload:
+            # This must be done before open() is called as the 'io' module
+            # implicitly imports 'locale' and would otherwise trigger an
+            # infinite loop.
+            module = imp.new_module(fullname)
+            module.__name__ = fullname
+            sys.modules[fullname] = module
+        else:
+            original_values = {}
+            modified_attrs = ['__loader__', '__name__', '__file__', '__path__']
+            for attr in modified_attrs:
+                try:
+                    original_values[attr] = getattr(module, attr)
+                except AttributeError:
+                    pass
+        try:
+            return fxn(self, module)
+        except:
+            if not is_reload:
+                del sys.modules[fullname]
+            else:
+                for attr in modified_attrs:
+                    if attr in original_values:
+                        setattr(module, attr, original_values[attr])
+                    elif hasattr(module, attr):
+                        delattr(module, attr)
+            raise
+    return decorated
+
+
+class _PyFileLoader(object):
+    # XXX Still smart to have this as a separate class?  Or would it work
+    # better to integrate with PyFileImporter?  Could cache _is_pkg info.
+    # FileImporter can be changed to return self instead of a specific loader
+    # call.  Otherwise _base_path can be calculated on the fly without issue if
+    # it is known whether a module should be treated as a path or package to
+    # minimize stat calls.  Could even go as far as to stat the directory the
+    # importer is in to detect changes and then cache all the info about what
+    # files were found (if stating directories is platform-dependent).
+
+    """Load a Python source or bytecode file."""
+
+    def __init__(self, name, path, is_pkg):
+        self._name = name
+        self._is_pkg = is_pkg
+        # Figure out the base path based on whether it was source or bytecode
+        # that was found.
+        try:
+            self._base_path = _path_without_ext(path, imp.PY_SOURCE)
+        except ValueError:
+            self._base_path = _path_without_ext(path, imp.PY_COMPILED)
+
+    def _find_path(self, ext_type):
+        """Find a path from the base path and the specified extension type that
+        exists, returning None if one is not found."""
+        for suffix in suffix_list(ext_type):
+            path = self._base_path + suffix
+            if _path_exists(path):
+                return path
+        else:
+            return None
+
+    def _source_path(self):
+        """Return the path to an existing source file for the module, or None
+        if one cannot be found."""
+        # Not a property so that it is easy to override.
+        return self._find_path(imp.PY_SOURCE)
+
+    def _bytecode_path(self):
+        """Return the path to a bytecode file, or None if one does not
+        exist."""
+        # Not a property for easy overriding.
+        return self._find_path(imp.PY_COMPILED)
+
+    @check_name
+    @get_module
+    def load_module(self, module):
+        """Load a Python source or bytecode module."""
+        source_path = self._source_path()
+        bytecode_path = self._bytecode_path()
+        code_object = self.get_code(module.__name__)
+        module.__file__ = source_path if source_path else bytecode_path
+        module.__loader__ = self
+        if self._is_pkg:
+            module.__path__  = [module.__file__.rsplit(path_sep, 1)[0]]
+            module.__package__ = module.__name__
+        elif '.' in module.__name__:
+            module.__package__ = module.__name__.rsplit('.', 1)[0]
+        else:
+            module.__package__ = None
+        exec(code_object, module.__dict__)
+        return module
+
+    @check_name
+    def source_mtime(self, name):
+        """Return the modification time of the source for the specified
+        module."""
+        source_path = self._source_path()
+        if not source_path:
+            return None
+        return int(_os.stat(source_path).st_mtime)
+
+    @check_name
+    def get_source(self, fullname):
+        """Return the source for the module as a string.
+
+        Return None if the source is not available. Raise ImportError if the
+        laoder cannot handle the specified module.
+
+        """
+        source_path = self._source_path()
+        if source_path is None:
+            return None
+        import tokenize
+        with closing(_fileio_FileIO(source_path, 'r')) as file:
+            encoding, lines = tokenize.detect_encoding(file.readline)
+        # XXX Will fail when passed to compile() if the encoding is
+        # anything other than UTF-8.
+        return open(source_path, encoding=encoding).read()
+
+    @check_name
+    def read_source(self, fullname):
+        """Return the source for the specified module as bytes along with the
+        path where the source came from.
+
+        The returned path is used by 'compile' for error messages.
+
+        """
+        source_path = self._source_path()
+        if source_path is None:
+            return None
+        with closing(_fileio._FileIO(source_path, 'r')) as bytes_file:
+            return bytes_file.read(), source_path
+
+    @check_name
+    def read_bytecode(self, name):
+        """Return the magic number, timestamp, and the module bytecode for the
+        module.
+
+        Raises ImportError (just like get_source) if the laoder cannot handle
+        the module. Returns None if there is no bytecode.
+
+        """
+        path = self._bytecode_path()
+        if path is None:
+            return None
+        file = _fileio._FileIO(path, 'r')
+        try:
+            with closing(file) as bytecode_file:
+                data = bytecode_file.read()
+            return data[:4], marshal._r_long(data[4:8]), data[8:]
+        except AttributeError:
+            return None
+
+    @check_name
+    def write_bytecode(self, name, magic, timestamp, data):
+        """Write out 'data' for the specified module using the specific
+        timestamp, returning a boolean
+        signifying if the write-out actually occurred.
+
+        Raises ImportError (just like get_source) if the specified module
+        cannot be handled by the loader.
+
+        """
+        bytecode_path = self._bytecode_path()
+        if not bytecode_path:
+            bytecode_path = self._base_path + suffix_list(imp.PY_COMPILED)[0]
+        file = _fileio._FileIO(bytecode_path, 'w')
+        try:
+            with closing(file) as bytecode_file:
+                bytecode_file.write(magic)
+                bytecode_file.write(marshal._w_long(timestamp))
+                bytecode_file.write(data)
+                return True
+        except IOError as exc:
+            if exc.errno == errno.EACCES:
+                return False
+            else:
+                raise
+
+    # XXX Take an optional argument to flag whether to write bytecode?
+    @check_name
+    def get_code(self, name):
+        """Return the code object for the module.
+
+            'self' must implement:
+
+            * read_bytecode(name:str) -> (int, int, bytes) or None
+                Return the magic number, timestamp, and bytecode for the
+                module. None is returned if not bytecode is available.
+
+            * source_mtime(name:str) -> int
+                Return the last modification time for the source of the module.
+                Returns None if their is no source.
+
+            * read_source(name:str) -> (bytes, str)
+                Return the source code for the module and the path to use in
+                the call to 'compile'. Not called if source_mtime returned
+                None.
+
+            * write_bytecode(name:str, magic:bytes, timestamp:int, data:str)
+                Write out bytecode for the module with the specified magic
+                number and timestamp. Not called if sys.dont_write_bytecode is
+                True.
+
+        """
+        # XXX Care enough to make sure this call does not happen if the magic
+        #     number is bad?
+        source_timestamp = self.source_mtime(name)
+        # Try to use bytecode if it is available.
+        bytecode_tuple = self.read_bytecode(name)
+        if bytecode_tuple:
+            magic, pyc_timestamp, bytecode = bytecode_tuple
+            try:
+                # Verify that the magic number is valid.
+                if imp.get_magic() != magic:
+                    raise ImportError("bad magic number")
+                # Verify that the bytecode is not stale (only matters when
+                # there is source to fall back on.
+                if source_timestamp:
+                    if pyc_timestamp < source_timestamp:
+                        raise ImportError("bytcode is stale")
+            except ImportError:
+                # If source is available give it a shot.
+                if source_timestamp is not None:
+                    pass
+                else:
+                    raise
+            else:
+                # Bytecode seems fine, so try to use it.
+                # XXX If the bytecode is ill-formed, would it be beneficial to
+                #     try for using source if available and issue a warning?
+                return marshal.loads(bytecode)
+        elif source_timestamp is None:
+            raise ImportError("no source or bytecode available to create code "
+                                "object for {0!r}".format(name))
+        # Use the source.
+        source, source_path = self.read_source(name)
+        # Convert to universal newlines.
+        line_endings = b'\n'
+        for index, c in enumerate(source):
+            if c == ord(b'\n'):
+                break
+            elif c == ord(b'\r'):
+                line_endings = b'\r'
+                try:
+                    if source[index+1] == ord(b'\n'):
+                        line_endings += b'\n'
+                except IndexError:
+                    pass
+                break
+        if line_endings != b'\n':
+            source = source.replace(line_endings, b'\n')
+        code_object = compile(source, source_path, 'exec', dont_inherit=True)
+        # Generate bytecode and write it out.
+        if not sys.dont_write_bytecode:
+            data = marshal.dumps(code_object)
+            self.write_bytecode(name, imp.get_magic(), source_timestamp, data)
+        return code_object
+
+    def get_data(self, path):
+        """Return the data from path as raw bytes."""
+        return _fileio._FileIO(path, 'r').read()
+
+    @check_name
+    def is_package(self, fullname):
+        """Return a boolean based on whether the module is a package.
+
+        Raises ImportError (like get_source) if the loader cannot handle the
+        package.
+
+        """
+        return self._is_pkg
+
+
+class FileImporter(object):
+
+    """Base class for file importers.
+
+    Subclasses are expected to define the following attributes:
+
+        * _suffixes
+            Sequence of file suffixes whose order will be followed.
+
+        * _possible_package
+            True if importer should check for packages.
+
+        * _loader
+            A callable that takes the module name, a file path, and whether
+            the path points to a package and returns a loader for the module
+            found at that path.
+
+    """
+
+    def __init__(self, path_entry):
+        """Initialize an importer for the passed-in sys.path entry (which is
+        assumed to have already been verified as an existing directory).
+
+        Can be used as an entry on sys.path_hook.
+
+        """
+        self._path_entry = path_entry
+
+    def find_module(self, fullname, path=None):
+        tail_module = fullname.rsplit('.', 1)[-1]
+        package_directory = None
+        if self._possible_package:
+            for ext in self._suffixes:
+                package_directory = _path_join(self._path_entry, tail_module)
+                init_filename = '__init__' + ext
+                package_init = _path_join(package_directory, init_filename)
+                if (_path_isfile(package_init) and
+                        _case_ok(self._path_entry, tail_module) and
+                        _case_ok(package_directory, init_filename)):
+                    return self._loader(fullname, package_init, True)
+        for ext in self._suffixes:
+            file_name = tail_module + ext
+            file_path = _path_join(self._path_entry, file_name)
+            if (_path_isfile(file_path) and
+                    _case_ok(self._path_entry, file_name)):
+                return self._loader(fullname, file_path, False)
+        else:
+            # Raise a warning if it matches a directory w/o an __init__ file.
+            if (package_directory is not None and
+                    _path_isdir(package_directory) and
+                    _case_ok(self._path_entry, tail_module)):
+                _warnings.warn("Not importing directory %s: missing __init__"
+                                % package_directory, ImportWarning)
+            return None
+
+
+class ExtensionFileImporter(FileImporter):
+
+    """Importer for extension files."""
+
+    _possible_package = False
+    _loader = _ExtensionFileLoader
+
+    def __init__(self, path_entry):
+        # Assigning to _suffixes here instead of at the class level because
+        # imp is not imported at the time of class creation.
+        self._suffixes = suffix_list(imp.C_EXTENSION)
+        super(ExtensionFileImporter, self).__init__(path_entry)
+
+
+class PyFileImporter(FileImporter):
+
+    """Importer for source/bytecode files."""
+
+    _possible_package = True
+    _loader = _PyFileLoader
+
+    def __init__(self, path_entry):
+        # Lack of imp during class creation means _suffixes is set here.
+        # Make sure that Python source files are listed first!  Needed for an
+        # optimization by the loader.
+        self._suffixes = suffix_list(imp.PY_SOURCE)
+        self._suffixes += suffix_list(imp.PY_COMPILED)
+        super(PyFileImporter, self).__init__(path_entry)
+
+
+class ImportLockContext(object):
+
+    """Context manager for the import lock."""
+
+    def __enter__(self):
+        """Acquire the import lock."""
+        imp.acquire_lock()
+
+    def __exit__(self, exc_type, exc_value, exc_traceback):
+        """Release the import lock regardless of any raised exceptions."""
+        imp.release_lock()
+
+
+class Import(object):
+
+    """Class that implements the __import__ interface.
+
+    Backwards compatibility is maintained  by extending sys.meta_path
+    interally (for handling built-in and frozen modules) and providing a
+    default path hooks entry for extension modules, .py, and .pyc
+    files.  Both are controlled during instance initialization.
+
+    """
+
+    def __init__(self, default_path_hook=None,
+                 extended_meta_path=None):
+        """Store a default path hook entry and a sequence to internally extend
+        sys.meta_path by (passing in None uses default importers)."""
+        if extended_meta_path is None:
+            self.extended_meta_path = BuiltinImporter(), FrozenImporter()
+        else:
+            self.extended_meta_path = extended_meta_path
+        self.default_path_hook = default_path_hook
+        if self.default_path_hook is None:
+            # Create a handler to deal with extension modules, .py, and .pyc
+            # files.  Built-in and frozen modules are handled by sys.meta_path
+            # entries.
+            importers = [ExtensionFileImporter, PyFileImporter]
+            self.default_path_hook = chaining_fs_path_hook(*importers)
+
+    def _search_meta_path(self, name, path=None):
+        """Check the importers on sys.meta_path for a loader along with the
+        extended meta path sequence stored within this instance.
+
+        The extended sys.meta_path entries are searched after the entries on
+        sys.meta_path.
+
+        """
+        for entry in (tuple(sys.meta_path) + self.extended_meta_path):
+            loader = entry.find_module(name, path)
+            if loader:
+                return loader
+        else:
+            raise ImportError("No module named %s" % name)
+
+    def _sys_path_importer(self, path_entry):
+        """Return the importer for the specified path, from
+        sys.path_importer_cache if possible.
+
+        If None is stored in sys.path_importer_cache then use the default path
+        hook.
+
+        """
+        try:
+            # See if an importer is cached.
+            importer = sys.path_importer_cache[path_entry]
+            # If None was returned, use default importer factory.
+            if importer is None:
+                return self.default_path_hook(path_entry)
+            else:
+                return importer
+        except KeyError:
+            # No cached importer found; try to get a new one from
+            # sys.path_hooks or imp.NullImporter.
+            for importer_factory in (sys.path_hooks + [imp.NullImporter]):
+                try:
+                    importer = importer_factory(path_entry)
+                    sys.path_importer_cache[path_entry] = importer
+                    return importer
+                except ImportError:
+                    continue
+            else:
+                # No importer factory on sys.path_hooks works; use the default
+                # importer factory and store None in sys.path_importer_cache.
+                try:
+                    importer = self.default_path_hook(path_entry)
+                    sys.path_importer_cache[path_entry] = None
+                    return importer
+                except ImportError:
+                    raise ImportError("no importer found for %s" % path_entry)
+
+    def _search_std_path(self, name, path=None):
+        """Check sys.path or 'path' (depending if 'path' is set) for the
+        named module and return its loader."""
+        if path:
+            search_paths = path
+        else:
+            search_paths = sys.path
+        for entry in search_paths:
+            try:
+                importer = self._sys_path_importer(entry)
+            except ImportError:
+                continue
+            loader = importer.find_module(name)
+            if loader:
+                return loader
+        else:
+            raise ImportError("No module named %s" % name)
+
+    def module_from_cache(self, name):
+        """Try to return the named module from sys.modules.
+
+        Return False if the module is not in the cache.
+        """
+        if name in sys.modules:
+            return sys.modules[name]
+        else:
+            return False
+
+    def post_import(self, module):
+        """Perform any desired post-import processing on the module."""
+        return module
+
+    def _import_module(self, name, path=None):
+        """Import the specified module with no handling of parent modules.
+
+        If None is set for a value in sys.modules (to signify that a relative
+        import was attempted and failed) then ImportError is raised.
+
+        """
+        cached_module = self.module_from_cache(name)
+        if cached_module is not False:
+            if cached_module is None:
+                raise ImportError("relative import redirect")
+            else:
+                return cached_module
+        try:
+            # Attempt to find a loader on sys.meta_path.
+            loader = self._search_meta_path(name, path)
+        except ImportError:
+            # sys.meta_path search failed.  Attempt to find a loader on
+            # sys.path.  If this fails then module cannot be found.
+            loader = self._search_std_path(name, path)
+        # A loader was found.  It is the loader's responsibility to have put an
+        # entry in sys.modules.
+        module = self.post_import(loader.load_module(name))
+        # 'module' could be something like None.
+        if not hasattr(module, '__name__'):
+            return module
+        # Set __package__.
+        if not hasattr(module, '__package__') or module.__package__ is None:
+            if hasattr(module, '__path__'):
+                module.__package__ = module.__name__
+            elif '.' in module.__name__:
+                pkg_name = module.__name__.rsplit('.', 1)[0]
+                module.__package__ = pkg_name
+            else:
+                module.__package__ = None
+        return module
+
+
+    def _import_full_module(self, name):
+        """Import a module and set it on its parent if needed."""
+        path_list = None
+        parent_name = name.rsplit('.', 1)[0]
+        parent = None
+        if parent_name != name:
+            parent = sys.modules[parent_name]
+            try:
+                path_list = parent.__path__
+            except AttributeError:
+                pass
+        self._import_module(name, path_list)
+        module = sys.modules[name]
+        if parent:
+            tail = name.rsplit('.', 1)[-1]
+            setattr(parent, tail, module)
+
+    def _find_package(self, name, has_path):
+        """Return the package that the caller is in or None."""
+        if has_path:
+            return name
+        elif '.' in name:
+            return name.rsplit('.', 1)[0]
+        else:
+            return None
+
+    @staticmethod
+    def _resolve_name(name, package, level):
+        """Return the absolute name of the module to be imported."""
+        level -= 1
+        try:
+            if package.count('.') < level:
+                raise ValueError("attempted relative import beyond top-level "
+                                  "package")
+        except AttributeError:
+            raise ValueError("__package__ not set to a string")
+        base = package.rsplit('.', level)[0]
+        if name:
+            return "{0}.{1}".format(base, name)
+        else:
+            return base
+
+    def _return_module(self, absolute_name, relative_name, fromlist):
+        """Return the proper module based on what module was requested (and its
+        absolute module name), who is requesting it, and whether any specific
+        attributes were specified.
+
+        The semantics of this method revolve around 'fromlist'.  When it is
+        empty, the module up to the first dot is to be returned.  When the
+        module being requested is an absolute name this is simple (and
+        relative_name is an empty string).  But if the requested module was
+        a relative import (as signaled by relative_name having a non-false
+        value), then the name up to the first dot in the relative name resolved
+        to an absolute name is to be returned.
+
+        When fromlist is not empty and the module being imported is a package,
+        then the values
+        in fromlist need to be checked for.  If a value is not a pre-existing
+        attribute a relative import is attempted.  If it fails then suppressed
+        the failure silently.
+
+        """
+        if not fromlist:
+            if relative_name:
+                absolute_base = absolute_name.rpartition(relative_name)[0]
+                relative_head = relative_name.split('.', 1)[0]
+                to_return = absolute_base + relative_head
+            else:
+                to_return = absolute_name.split('.', 1)[0]
+            return sys.modules[to_return]
+        # When fromlist is not empty, return the actual module specified in
+        # the import.
+        else:
+            module = sys.modules[absolute_name]
+            if hasattr(module, '__path__') and hasattr(module, '__name__'):
+                # When fromlist has a value and the imported module is a
+                # package, then if a name in fromlist is not found as an
+                # attribute on module, try a relative import to find it.
+                # Failure is fine and the exception is suppressed.
+                check_for = list(fromlist)
+                if '*' in check_for and hasattr(module, '__all__'):
+                    check_for.extend(module.__all__)
+                for item in check_for:
+                    if item == '*':
+                        continue
+                    if not hasattr(module, item):
+                        resolved_name = self._resolve_name(item,
+                                                            module.__name__, 1)
+                        try:
+                            self._import_full_module(resolved_name)
+                        except ImportError:
+                            pass
+            return module
+
+    def __call__(self, name, globals={}, locals={}, fromlist=[], level=0):
+        """Import a module.
+
+        The 'name' argument is the name of the module to be imported (e.g.,
+        'foo' in ``import foo`` or ``from foo import ...``).
+
+        'globals' and 'locals' are the global and local namespace dictionaries
+        of the module where the import statement appears.  'globals' is used to
+        introspect the __path__ and __name__ attributes of the module making
+        the call.  'local's is ignored.
+
+        'fromlist' lists any specific objects that are to eventually be put
+        into the namespace (e.g., ``from for.bar import baz`` would have 'baz'
+        in the fromlist, and this includes '*').  An entry of '*' will lead to
+        a check for __all__ being defined on the module.  If it is defined then
+        the values in __all__ will be checked to make sure that all values are
+        attributes on the module, attempting a module import relative to 'name'
+        to set that attribute.
+
+        When 'name' is a dotted name, there are two different situations to
+        consider for the return value.  One is when the fromlist is empty.
+        In this situation the import statement imports and returns the name up
+        to the first dot.  All subsequent names are imported but set as
+        attributes as needed on parent modules.  When fromlist is not empty
+        then the module represented by the full dotted name is returned.
+
+        'level' represents possible relative imports.
+        A value of 0 is for absolute module names. Any positive value
+        represents the number of dots listed in the relative import statement
+        (e.g. has a value of 2 for ``from .. import foo``).
+
+        """
+        if not name and level < 1:
+            raise ValueError("Empty module name")
+        is_pkg = True if '__path__' in globals else False
+        caller_name = globals.get('__name__')
+        package = globals.get('__package__')
+        if caller_name and not package:
+            package = self._find_package(caller_name, '__path__' in globals)
+        if package and package not in sys.modules:
+            if not hasattr(package, 'rsplit'):
+                raise ValueError("__package__ not set to a string")
+            msg = ("Parent module {0!r} not loaded, "
+                    "cannot perform relative import")
+            raise SystemError(msg.format(package))
+        with ImportLockContext():
+            if level:
+                imported_name = self._resolve_name(name, package, level)
+            else:
+                imported_name = name
+            parent_name = imported_name.rsplit('.', 1)[0]
+            if parent_name != imported_name and parent_name not in sys.modules:
+                self.__call__(parent_name, level=0)
+            # This call will also handle setting the attribute on the
+            # package.
+            self._import_full_module(imported_name)
+            relative_name = '' if imported_name == name else name
+            return self._return_module(imported_name, relative_name, fromlist)
+
+# XXX Eventually replace with a proper __all__ value (i.e., don't expose os
+# replacements but do expose _ExtensionFileLoader, etc. for testing).
+__all__ = [obj for obj in globals().keys() if not obj.startswith('__')]

Lib/importlib/test/__init__.py

@@ -0,0 +1,26 @@
+import os.path
+import sys
+import unittest
+
+
+def test_suite(package=__package__, directory=os.path.dirname(__file__)):
+    suite = unittest.TestSuite()
+    for name in os.listdir(directory):
+        path = os.path.join(directory, name)
+        if os.path.isfile(path) and name.startswith('test_'):
+            submodule_name = os.path.splitext(name)[0]
+            module_name = "{0}.{1}".format(package, submodule_name)
+            __import__(module_name, level=0)
+            module_tests = unittest.findTestCases(sys.modules[module_name])
+            suite.addTest(module_tests)
+        elif os.path.isdir(path):
+            package_name = "{0}.{1}".format(package, name)
+            __import__(package_name, level=0)
+            package_tests = getattr(sys.modules[package_name], 'test_suite')()
+            suite.addTest(package_tests)
+    return suite
+
+
+if __name__ == '__main__':
+    from test.support import run_unittest
+    run_unittest(test_suite('importlib.test'))

Lib/importlib/test/builtin/__init__.py

@@ -0,0 +1,12 @@
+import importlib.test
+import os
+
+
+def test_suite():
+    directory = os.path.dirname(__file__)
+    return importlib.test.test_suite('importlib.test.builtin', directory)
+
+
+if __name__ == '__main__':
+    from test.support import run_unittest
+    run_unittest(test_suite())

Lib/importlib/test/builtin/test_finder.py

@@ -0,0 +1,36 @@
+import importlib
+from .. import support
+
+import sys
+import unittest
+
+class FinderTests(unittest.TestCase):
+
+    """Test find_module() for built-in modules."""
+
+    assert 'errno' in sys.builtin_module_names
+    name = 'errno'
+
+    find_module = staticmethod(lambda name, path=None:
+                    importlib.BuiltinImporter().find_module(name, path))
+
+
+    def test_find_module(self):
+        # Common case.
+        with support.uncache(self.name):
+            self.assert_(self.find_module(self.name))
+
+    def test_ignore_path(self):
+        # The value for 'path' should always trigger a failed import.
+        with support.uncache(self.name):
+            self.assert_(self.find_module(self.name, ['pkg']) is None)
+
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(FinderTests)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/builtin/test_loader.py

@@ -0,0 +1,52 @@
+import importlib
+from .. import support
+
+import sys
+import types
+import unittest
+
+
+class LoaderTests(unittest.TestCase):
+
+    """Test load_module() for built-in modules."""
+
+    assert 'errno' in sys.builtin_module_names
+    name = 'errno'
+
+    verification = {'__name__': 'errno', '__package__': None}
+
+    def verify(self, module):
+        """Verify that the module matches against what it should have."""
+        self.assert_(isinstance(module, types.ModuleType))
+        for attr, value in self.verification.items():
+            self.assertEqual(getattr(module, attr), value)
+        self.assert_(module.__name__ in sys.modules)
+
+    load_module = staticmethod(lambda name:
+                                importlib.BuiltinImporter().load_module(name))
+
+    def test_load_module(self):
+        # Common case.
+        with support.uncache(self.name):
+            module = self.load_module(self.name)
+            self.verify(module)
+
+    def test_nonexistent(self):
+        name = 'dssdsdfff'
+        assert name not in sys.builtin_module_names
+        self.assertRaises(ImportError, self.load_module, name)
+
+    def test_already_imported(self):
+        # Using the name of a module already imported but not a built-in should
+        # still fail.
+        assert hasattr(importlib, '__file__')  # Not a built-in.
+        self.assertRaises(ImportError, self.load_module, 'importlib')
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(LoaderTests)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/extension/__init__.py

@@ -0,0 +1,13 @@
+import importlib.test
+import os.path
+import unittest
+
+
+def test_suite():
+    directory = os.path.dirname(__file__)
+    return importlib.test.test_suite('importlib.test.extension', directory)
+
+
+if __name__ == '__main__':
+    from test.support import run_unittest
+    run_unittest(test_suite())

Lib/importlib/test/extension/test_case_sensitivity.py

@@ -0,0 +1,39 @@
+import sys
+from test import support as test_support
+import unittest
+import importlib
+from . import test_path_hook
+
+
+class ExtensionModuleCaseSensitivityTest(unittest.TestCase):
+
+    def find_module(self):
+        good_name = test_path_hook.NAME
+        bad_name = good_name.upper()
+        assert good_name != bad_name
+        finder = importlib.ExtensionFileImporter(test_path_hook.PATH)
+        return finder.find_module(bad_name)
+
+    def test_case_sensitive(self):
+        with test_support.EnvironmentVarGuard() as env:
+            env.unset('PYTHONCASEOK')
+            loader = self.find_module()
+            self.assert_(loader is None)
+
+    def test_case_insensitivity(self):
+        with test_support.EnvironmentVarGuard() as env:
+            env.set('PYTHONCASEOK', '1')
+            loader = self.find_module()
+            self.assert_(hasattr(loader, 'load_module'))
+
+
+
+
+def test_main():
+    if sys.platform not in ('win32', 'darwin', 'cygwin'):
+        return
+    test_support.run_unittest(ExtensionModuleCaseSensitivityTest)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/extension/test_finder.py

@@ -0,0 +1,29 @@
+import importlib
+from . import test_path_hook
+
+import unittest
+
+class FinderTests(unittest.TestCase):
+
+    """Test the finder for extension modules."""
+
+    def find_module(self, fullname):
+        importer = importlib.ExtensionFileImporter(test_path_hook.PATH)
+        return importer.find_module(fullname)
+
+    def test_success(self):
+        self.assert_(self.find_module(test_path_hook.NAME))
+
+    def test_failure(self):
+        self.assert_(self.find_module('asdfjkl;') is None)
+
+    # XXX Raise an exception if someone tries to use the 'path' argument?
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(FinderTests)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/extension/test_loader.py

@@ -0,0 +1,37 @@
+import importlib
+from . import test_path_hook
+from .. import support
+
+import sys
+import unittest
+
+
+class LoaderTests(unittest.TestCase):
+
+    """Test load_module() for extension modules."""
+
+    def load_module(self, fullname):
+        loader = importlib._ExtensionFileLoader(test_path_hook.NAME,
+                                                test_path_hook.FILEPATH,
+                                                False)
+        return loader.load_module(fullname)
+
+    def test_success(self):
+        with support.uncache(test_path_hook.NAME):
+            module = self.load_module(test_path_hook.NAME)
+            for attr, value in [('__name__', test_path_hook.NAME),
+                                ('__file__', test_path_hook.FILEPATH)]:
+                self.assertEqual(getattr(module, attr), value)
+            self.assert_(test_path_hook.NAME in sys.modules)
+
+    def test_failure(self):
+        self.assertRaises(ImportError, self.load_module, 'asdfjkl;')
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(LoaderTests)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/extension/test_path_hook.py

@@ -0,0 +1,50 @@
+import importlib
+
+import collections
+import imp
+from os import path
+import sys
+import unittest
+
+
+PATH = None
+EXT = None
+FILENAME = None
+NAME = '_testcapi'
+_file_exts = [x[0] for x in imp.get_suffixes() if x[2] == imp.C_EXTENSION]
+try:
+    for PATH in sys.path:
+        for EXT in _file_exts:
+            FILENAME = NAME + EXT
+            FILEPATH = path.join(PATH, FILENAME)
+            if path.exists(path.join(PATH, FILENAME)):
+                raise StopIteration
+    else:
+        PATH = EXT = FILENAME = FILEPATH = None
+except StopIteration:
+    pass
+del _file_exts
+
+
+class PathHookTests(unittest.TestCase):
+
+    """Test the path hook for extension modules."""
+    # XXX Should it only succeed for pre-existing directories?
+    # XXX Should it only work for directories containing an extension module?
+
+    def hook(self, entry):
+        return importlib.ExtensionFileImporter(entry)
+
+    def test_success(self):
+        # Path hook should handle a directory where a known extension module
+        # exists.
+        self.assert_(hasattr(self.hook(PATH), 'find_module'))
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(PathHookTests)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/finder_tests.py

@@ -0,0 +1,39 @@
+# top-level.
+# Package.
+# module in pacakge.
+# Package within a package.
+# At least one tests with 'path'.
+# Module that is not handled.
+
+import unittest
+
+
+class FinderTests(unittest.TestCase):
+
+    """Basic tests for a finder to pass."""
+
+    def test_module(self):
+        # Test importing a top-level module.
+        raise NotImplementedError
+
+    def test_package(self):
+        # Test importing a package.
+        raise NotImplementedError
+
+    def test_module_in_package(self):
+        # Test importing a module contained within a package.
+        # A value for 'path' should be used if for a meta_path finder.
+        raise NotImplementedError
+
+    def test_package_in_package(self):
+        # Test importing a subpackage.
+        # A value for 'path' should be used if for a meta_path finder.
+        raise NotImplementedError
+
+    def test_package_over_module(self):
+        # Test that packages are chosen over modules.
+        raise NotImplementedError
+
+    def test_failure(self):
+        # Test trying to find a module that cannot be handled.
+        raise NotImplementedError

Lib/importlib/test/frozen/__init__.py

@@ -0,0 +1,13 @@
+import importlib.test
+import os.path
+import unittest
+
+
+def test_suite():
+    directory = os.path.dirname(__file__)
+    return importlib.test.test_suite('importlib.test.frozen', directory)
+
+
+if __name__ == '__main__':
+    from test.support import run_unittest
+    run_unittest(test_suite())

Lib/importlib/test/frozen/support.py

@@ -0,0 +1,24 @@
+import sys
+
+
+class Null:
+
+    """Just absorb what is given."""
+
+    def __getattr__(self):
+        return lambda *args, **kwargs: None
+
+
+class SilenceStdout:
+
+    """Silence sys.stdout."""
+
+    def setUp(self):
+        """Substitute sys.stdout with something that does not print to the
+        screen thanks to what bytecode is frozen."""
+        sys.stdout = Null()
+        super().setUp()
+
+    def tearDown(self):
+        sys.stdout = sys.__stdout__
+        super().tearDown()

Lib/importlib/test/frozen/test_finder.py

@@ -0,0 +1,44 @@
+import importlib
+from ..builtin import test_finder
+from .. import support
+
+import unittest
+
+
+class FinderTests(test_finder.FinderTests):
+
+    """Test finding frozen modules."""
+
+    def find(self, name, path=None):
+        finder = importlib.FrozenImporter()
+        return finder.find_module(name, path)
+
+
+    def test_module(self):
+        name = '__hello__'
+        loader = self.find(name)
+        self.assert_(hasattr(loader, 'load_module'))
+
+    def test_package(self):
+        loader = self.find('__phello__')
+        self.assert_(hasattr(loader, 'load_module'))
+
+    def test_module_in_package(self):
+        loader = self.find('__phello__.spam', ['__phello__'])
+        self.assert_(hasattr(loader, 'load_module'))
+
+    def test_package_in_package(self):
+        pass
+
+    def test_failure(self):
+        loader = self.find('<not real>')
+        self.assert_(loader is None)
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(FinderTests)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/frozen/test_loader.py

@@ -0,0 +1,27 @@
+import importlib
+from ..builtin import test_loader
+
+
+class LoaderTests(test_loader.LoaderTests):
+
+    name = '__phello__'
+    load_module = staticmethod(lambda name:
+                                importlib.FrozenImporter().load_module(name))
+    verification = {'__name__': '__phello__', '__file__': '<frozen>',
+                    '__package__': None, '__path__': ['__phello__']}
+
+
+class SubmoduleLoaderTests(LoaderTests):
+
+    name = '__phello__.spam'
+    verification = {'__name__': '__phello__.spam', '__file__': '<frozen>',
+                    '__package__': None}
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(LoaderTests, SubmoduleLoaderTests)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/import_/__init__.py

@@ -0,0 +1,13 @@
+import importlib.test
+import os.path
+import unittest
+
+
+def test_suite():
+    directory = os.path.dirname(__file__)
+    return importlib.test.test_suite('importlib.test.import_', directory)
+
+
+if __name__ == '__main__':
+    from test.support import run_unittest
+    run_unittest(test_suite())

Lib/importlib/test/import_/test___package__.py

@@ -0,0 +1,110 @@
+"""PEP 366 ("Main module explicit relative imports") specifies the
+semantics for the __package__ attribute on modules. This attribute is
+used, when available, to detect which package a module belongs to (instead
+of using the typical __path__/__name__ test).
+
+"""
+import unittest
+from .. import support
+
+
+class Using__package__(unittest.TestCase):
+
+    """Use of __package__ supercedes the use of __name__/__path__ to calculate
+    what package a module belongs to. The basic algorithm is [__package__]::
+
+      def resolve_name(name, package, level):
+          level -= 1
+          base = package.rsplit('.', level)[0]
+          return '{0}.{1}'.format(base, name)
+
+    But since there is no guarantee that __package__ has been set, there has to
+    be a way to calculate the attribute's value [__name__]::
+
+      def calc_package(caller_name, has___path__):
+          if has__path__:
+              return caller_name
+          else:
+              return caller_name.rsplit('.', 1)[0]
+
+    Then the normal algorithm for relative name imports can proceed as if
+    __package__ had been set.
+
+    """
+
+    def test_using___package__(self):
+        # [__package__]
+        with support.mock_modules('pkg.__init__', 'pkg.fake') as importer:
+            with support.import_state(meta_path=[importer]):
+                support.import_('pkg.fake')
+                module = support.import_('', globals={'__package__': 'pkg.fake'},
+                                 fromlist=['attr'], level=2)
+        self.assertEquals(module.__name__, 'pkg')
+
+    def test_using___name__(self):
+        # [__name__]
+        with support.mock_modules('pkg.__init__', 'pkg.fake') as importer:
+            with support.import_state(meta_path=[importer]):
+                support.import_('pkg.fake')
+                module = support.import_('',
+                                 globals={'__name__': 'pkg.fake',
+                                          '__path__': []},
+                                 fromlist=['attr'], level=2)
+            self.assertEquals(module.__name__, 'pkg')
+
+    def test_bad__package__(self):
+        globals = {'__package__': '<not real>'}
+        self.assertRaises(SystemError, support.import_,'', globals, {},
+                            ['relimport'], 1)
+
+    def test_bunk__package__(self):
+        globals = {'__package__': 42}
+        self.assertRaises(ValueError, support.import_, '', globals, {},
+                            ['relimport'], 1)
+
+
+class Setting__package__(unittest.TestCase):
+
+    """Because __package__ is a new feature, it is not always set by a loader.
+    Import will set it as needed to help with the transition to relying on
+    __package__.
+
+    For a top-level module, __package__ is set to None [top-level]. For a
+    package __name__ is used for __package__ [package]. For submodules the
+    value is __name__.rsplit('.', 1)[0] [submodule].
+
+    """
+
+    # [top-level]
+    def test_top_level(self):
+        with support.mock_modules('top_level') as mock:
+            with support.import_state(meta_path=[mock]):
+                del mock['top_level'].__package__
+                module = support.import_('top_level')
+                self.assert_(module.__package__ is None)
+
+    # [package]
+    def test_package(self):
+        with support.mock_modules('pkg.__init__') as mock:
+            with support.import_state(meta_path=[mock]):
+                del mock['pkg'].__package__
+                module = support.import_('pkg')
+                self.assertEqual(module.__package__, 'pkg')
+
+    # [submodule]
+    def test_submodule(self):
+        with support.mock_modules('pkg.__init__', 'pkg.mod') as mock:
+            with support.import_state(meta_path=[mock]):
+                del mock['pkg.mod'].__package__
+                pkg = support.import_('pkg.mod')
+                module = getattr(pkg, 'mod')
+                self.assertEqual(module.__package__, 'pkg')
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(Using__package__, Setting__package__)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/import_/test_caching.py

@@ -0,0 +1,75 @@
+"""Test that sys.modules is used properly by import."""
+from ..support import import_, mock_modules, importlib_only, import_state
+
+import sys
+from types import MethodType
+import unittest
+
+
+class UseCache(unittest.TestCase):
+
+    """When it comes to sys.modules, import prefers it over anything else.
+
+    Once a name has been resolved, sys.modules is checked to see if it contains
+    the module desired. If so, then it is returned [use cache]. If it is not
+    found, then the proper steps are taken to perform the import, but
+    sys.modules is still used to return the imported module (e.g., not what a
+    loader returns) [from cache on return]. This also applies to imports of
+    things contained within a package and thus get assigned as an attribute
+    [from cache to attribute] or pulled in thanks to a fromlist import
+    [from cache for fromlist].
+
+    """
+    def test_using_cache(self):
+        # [use cache]
+        module_to_use = "some module found!"
+        sys.modules['some_module'] = module_to_use
+        module = import_('some_module')
+        self.assertEqual(id(module_to_use), id(module))
+
+    def create_mock(self, *names, return_=None):
+        mock = mock_modules(*names)
+        original_load = mock.load_module
+        def load_module(self, fullname):
+            original_load(fullname)
+            return return_
+        mock.load_module = MethodType(load_module, mock)
+        return mock
+
+    # __import__ inconsistent between loaders and built-in import when it comes
+    #   to when to use the module in sys.modules and when not to.
+    @importlib_only
+    def test_using_cache_after_loader(self):
+        # [from cache on return]
+        with self.create_mock('module') as mock:
+            with import_state(meta_path=[mock]):
+                module = import_('module')
+                self.assertEquals(id(module), id(sys.modules['module']))
+
+    # See test_using_cache_after_loader() for reasoning.
+    @importlib_only
+    def test_using_cache_for_assigning_to_attribute(self):
+        # [from cache to attribute]
+        with self.create_mock('pkg.__init__', 'pkg.module') as importer:
+            with import_state(meta_path=[importer]):
+                module = import_('pkg.module')
+                self.assert_(hasattr(module, 'module'))
+                self.assert_(id(module.module), id(sys.modules['pkg.module']))
+
+    # See test_using_cache_after_loader() for reasoning.
+    @importlib_only
+    def test_using_cache_for_fromlist(self):
+        # [from cache for fromlist]
+        with self.create_mock('pkg.__init__', 'pkg.module') as importer:
+            with import_state(meta_path=[importer]):
+                module = import_('pkg', fromlist=['module'])
+                self.assert_(hasattr(module, 'module'))
+                self.assertEquals(id(module.module), id(sys.modules['pkg.module']))
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(UseCache)
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/import_/test_fromlist.py

@@ -0,0 +1,116 @@
+"""Test that the semantics relating to the 'fromlist' argument are correct."""
+from ..support import import_, mock_modules, import_state
+
+import unittest
+
+class ReturnValue(unittest.TestCase):
+
+    """The use of fromlist influences what import returns.
+
+    If direct ``import ...`` statement is used, the root module or package is
+    returned [import return]. But if fromlist is set, then the specified module
+    is actually returned (whether it is a relative import or not)
+    [from return].
+
+    """
+
+    def test_return_from_import(self):
+        # [import return]
+        with mock_modules('pkg.__init__', 'pkg.module') as importer:
+            with import_state(meta_path=[importer]):
+                module = import_('pkg.module')
+                self.assertEquals(module.__name__, 'pkg')
+
+    def test_return_from_from_import(self):
+        # [from return]
+        with mock_modules('pkg.__init__', 'pkg.module')as importer:
+            with import_state(meta_path=[importer]):
+                module = import_('pkg.module', fromlist=['attr'])
+                self.assertEquals(module.__name__, 'pkg.module')
+
+
+class HandlingFromlist(unittest.TestCase):
+
+    """Using fromlist triggers different actions based on what is being asked
+    of it.
+
+    If fromlist specifies an object on a module, nothing special happens
+    [object case]. This is even true if the object does not exist [bad object].
+
+    If a package is being imported, then what is listed in fromlist may be
+    treated as a module to be imported [module]. But once again, even if
+    something in fromlist does not exist as a module, no error is thrown
+    [no module]. And this extends to what is contained in __all__ when '*' is
+    imported [using *]. And '*' does not need to be the only name in the
+    fromlist [using * with others].
+
+    """
+
+    def test_object(self):
+        # [object case]
+        with mock_modules('module') as importer:
+            with import_state(meta_path=[importer]):
+                module = import_('module', fromlist=['attr'])
+                self.assertEquals(module.__name__, 'module')
+
+    def test_unexistent_object(self):
+        # [bad object]
+        with mock_modules('module') as importer:
+            with import_state(meta_path=[importer]):
+                module = import_('module', fromlist=['non_existent'])
+                self.assertEquals(module.__name__, 'module')
+                self.assert_(not hasattr(module, 'non_existent'))
+
+    def test_module_from_package(self):
+        # [module]
+        with mock_modules('pkg.__init__', 'pkg.module') as importer:
+            with import_state(meta_path=[importer]):
+                module = import_('pkg', fromlist=['module'])
+                self.assertEquals(module.__name__, 'pkg')
+                self.assert_(hasattr(module, 'module'))
+                self.assertEquals(module.module.__name__, 'pkg.module')
+
+    def test_no_module_from_package(self):
+        # [no module]
+        with mock_modules('pkg.__init__') as importer:
+            with import_state(meta_path=[importer]):
+                module = import_('pkg', fromlist='non_existent')
+                self.assertEquals(module.__name__, 'pkg')
+                self.assert_(not hasattr(module, 'non_existent'))
+
+    def test_empty_string(self):
+        with mock_modules('pkg.__init__', 'pkg.mod') as importer:
+            with import_state(meta_path=[importer]):
+                module = import_('pkg.mod', fromlist=[''])
+                self.assertEquals(module.__name__, 'pkg.mod')
+
+    def test_using_star(self):
+        # [using *]
+        with mock_modules('pkg.__init__', 'pkg.module') as mock:
+            with import_state(meta_path=[mock]):
+                mock['pkg'].__all__ = ['module']
+                module = import_('pkg', fromlist=['*'])
+                self.assertEquals(module.__name__, 'pkg')
+                self.assert_(hasattr(module, 'module'))
+                self.assertEqual(module.module.__name__, 'pkg.module')
+
+    def test_star_with_others(self):
+        # [using * with others]
+        context = mock_modules('pkg.__init__', 'pkg.module1', 'pkg.module2')
+        with context as mock:
+            with import_state(meta_path=[mock]):
+                mock['pkg'].__all__ = ['module1']
+                module = import_('pkg', fromlist=['module2', '*'])
+                self.assertEquals(module.__name__, 'pkg')
+                self.assert_(hasattr(module, 'module1'))
+                self.assert_(hasattr(module, 'module2'))
+                self.assertEquals(module.module1.__name__, 'pkg.module1')
+                self.assertEquals(module.module2.__name__, 'pkg.module2')
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(ReturnValue, HandlingFromlist)
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/import_/test_meta_path.py

@@ -0,0 +1,99 @@
+from ..support import import_state, mock_modules, import_
+
+from contextlib import nested
+from types import MethodType
+import unittest
+
+
+class CallingOrder(unittest.TestCase):
+
+    """Calls to the importers on sys.meta_path happen in order that they are
+    specified in the sequence, starting with the first importer
+    [first called], and then continuing on down until one is found that doesn't
+    return None [continuing]."""
+
+
+    def test_first_called(self):
+        # [first called]
+        mod = 'top_level'
+        first = mock_modules(mod)
+        second = mock_modules(mod)
+        with nested(mock_modules(mod), mock_modules(mod)) as (first, second):
+            first.modules[mod] = 42
+            second.modules[mod] = -13
+            with import_state(meta_path=[first, second]):
+                self.assertEquals(import_(mod), 42)
+
+    def test_continuing(self):
+        # [continuing]
+        mod_name = 'for_real'
+        first = mock_modules('nonexistent')
+        second = mock_modules(mod_name)
+        with nested(first, second):
+            first.find_module = lambda self, fullname, path=None: None
+            second.modules[mod_name] = 42
+            with import_state(meta_path=[first, second]):
+                self.assertEquals(import_(mod_name), 42)
+
+
+class CallSignature(unittest.TestCase):
+
+    """If there is no __path__ entry on the parent module, then 'path' is None
+    [no path]. Otherwise, the value for __path__ is passed in for the 'path'
+    argument [path set]."""
+
+    def log(self, fxn):
+        log = []
+        def wrapper(self, *args, **kwargs):
+            log.append([args, kwargs])
+            return fxn(*args, **kwargs)
+        return log, wrapper
+
+
+    def test_no_path(self):
+        # [no path]
+        mod_name = 'top_level'
+        assert '.' not in mod_name
+        with mock_modules(mod_name) as importer:
+            log, wrapped_call = self.log(importer.find_module)
+            importer.find_module = MethodType(wrapped_call, importer)
+            with import_state(meta_path=[importer]):
+                import_(mod_name)
+                assert len(log) == 1
+                args = log[0][0]
+                kwargs = log[0][1]
+                # Assuming all arguments are positional.
+                self.assertEquals(len(args), 2)
+                self.assertEquals(len(kwargs), 0)
+                self.assertEquals(args[0], mod_name)
+                self.assert_(args[1] is None)
+
+    def test_with_path(self):
+        # [path set]
+        pkg_name = 'pkg'
+        mod_name = pkg_name + '.module'
+        path = [42]
+        assert '.' in mod_name
+        with mock_modules(pkg_name+'.__init__', mod_name) as importer:
+            importer.modules[pkg_name].__path__ = path
+            log, wrapped_call = self.log(importer.find_module)
+            importer.find_module = MethodType(wrapped_call, importer)
+            with import_state(meta_path=[importer]):
+                import_(mod_name)
+                assert len(log) == 2
+                args = log[1][0]
+                kwargs = log[1][1]
+                # Assuming all arguments are positional.
+                self.assert_(not kwargs)
+                self.assertEquals(args[0], mod_name)
+                self.assert_(args[1] is path)
+
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(CallingOrder, CallSignature)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/import_/test_packages.py

@@ -0,0 +1,29 @@
+import sys
+import unittest
+import importlib
+from .. import support
+
+
+class ParentModuleTests(unittest.TestCase):
+
+    """Importing a submodule should import the parent modules."""
+
+    def test_import_parent(self):
+        with support.mock_modules('pkg.__init__', 'pkg.module') as mock:
+            with support.import_state(meta_path=[mock]):
+                module = support.import_('pkg.module')
+                self.assert_('pkg' in sys.modules)
+
+    def test_bad_parent(self):
+        with support.mock_modules('pkg.module') as mock:
+            with support.import_state(meta_path=[mock]):
+                self.assertRaises(ImportError, support.import_, 'pkg.module')
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(ParentModuleTests)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/import_/test_path.py

@@ -0,0 +1,158 @@
+from ..support import (mock_modules, import_state, import_, mock_path_hook,
+                        importlib_only, uncache)
+
+from contextlib import nested
+from imp import new_module
+import sys
+from types import MethodType
+import unittest
+
+
+class BaseTests(unittest.TestCase):
+
+    """When sys.meta_path cannot find the desired module, sys.path is
+    consulted. For each entry on the sequence [order], sys.path_importer_cache
+    is checked to see if it contains a key for the entry [cache check]. If an
+    importer is found then it is consulted before trying the next entry in
+    sys.path [cache use]. The 'path' argument to find_module() is never used
+    when trying to find a module [path not used].
+
+    If an entry from sys.path is not in sys.path_importer_cache, sys.path_hooks
+    is called in turn [hooks order]. If a path hook cannot handle an entry,
+    ImportError is raised [hook failure]. Otherwise the resulting object is
+    cached in sys.path_importer_cache and then consulted [hook success]. If no
+    hook is found, None is set in sys.path_importer_cache and the default
+    importer is tried [no hook].
+
+    For use of __path__ in a package, the above is all true, just substitute
+    "sys.path" for "__path__".
+
+    """
+
+    def order_test(self, to_import, entry, search_path, path=[]):
+        # [order]
+        log = []
+        class LogFindModule(mock_modules):
+            def find_module(self, fullname):
+                log.append(self)
+                return super().find_module(fullname)
+
+        assert len(search_path) == 2
+        misser = LogFindModule(search_path[0])
+        hitter = LogFindModule(to_import)
+        with nested(misser, hitter):
+            cache = dict(zip(search_path, (misser, hitter)))
+            with import_state(path=path, path_importer_cache=cache):
+                import_(to_import)
+        self.assertEquals(log[0], misser)
+        self.assertEquals(log[1], hitter)
+
+    @importlib_only  # __import__ uses PyDict_GetItem(), bypassing log.
+    def cache_use_test(self, to_import, entry, path=[]):
+        # [cache check], [cache use]
+        log = []
+        class LoggingDict(dict):
+            def __getitem__(self, item):
+                log.append(item)
+                return super(LoggingDict, self).__getitem__(item)
+
+        with mock_modules(to_import) as importer:
+            cache = LoggingDict()
+            cache[entry] = importer
+            with import_state(path=[entry], path_importer_cache=cache):
+                module = import_(to_import, fromlist=['a'])
+            self.assert_(module is importer[to_import])
+        self.assertEquals(len(cache), 1)
+        self.assertEquals([entry], log)
+
+    def hooks_order_test(self, to_import, entry, path=[]):
+        # [hooks order], [hooks failure], [hook success]
+        log = []
+        def logging_hook(entry):
+            log.append(entry)
+            raise ImportError
+        with mock_modules(to_import) as importer:
+            hitter = mock_path_hook(entry, importer=importer)
+            path_hooks = [logging_hook, logging_hook, hitter]
+            with import_state(path_hooks=path_hooks, path=path):
+                import_(to_import)
+                self.assertEquals(sys.path_importer_cache[entry], importer)
+        self.assertEquals(len(log), 2)
+
+    # [no hook] XXX Worry about after deciding how to handle the default hook.
+
+    def path_argument_test(self, to_import):
+        # [path not used]
+        class BadImporter:
+            """Class to help detect TypeError from calling find_module() with
+            an improper number of arguments."""
+            def find_module(name):
+                raise ImportError
+
+        try:
+            import_(to_import)
+        except ImportError:
+            pass
+
+
+class PathTests(BaseTests):
+
+    """Tests for sys.path."""
+
+    def test_order(self):
+        self.order_test('hit', 'second', ['first', 'second'],
+                        ['first', 'second'])
+
+    def test_cache_use(self):
+        entry = "found!"
+        self.cache_use_test('hit', entry, [entry])
+
+    def test_hooks_order(self):
+        entry = "found!"
+        self.hooks_order_test('hit', entry, [entry])
+
+    def test_path_argument(self):
+        name = 'total junk'
+        with uncache(name):
+            self.path_argument_test(name)
+
+
+class __path__Tests(BaseTests):
+
+    """Tests for __path__."""
+
+    def run_test(self, test, entry, path, *args):
+        with mock_modules('pkg.__init__') as importer:
+            importer['pkg'].__path__ = path
+            importer.load_module('pkg')
+            test('pkg.hit', entry, *args)
+
+
+    @importlib_only  # XXX Unknown reason why this fails.
+    def test_order(self):
+        self.run_test(self.order_test, 'second', ('first', 'second'), ['first',
+            'second'])
+
+    def test_cache_use(self):
+        location = "I'm here!"
+        self.run_test(self.cache_use_test, location, [location])
+
+    def test_hooks_order(self):
+        location = "I'm here!"
+        self.run_test(self.hooks_order_test, location, [location])
+
+    def test_path_argument(self):
+        module = new_module('pkg')
+        module.__path__ = ['random __path__']
+        name = 'pkg.whatever'
+        sys.modules['pkg'] = module
+        with uncache('pkg', name):
+            self.path_argument_test(name)
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(PathTests, __path__Tests)
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/import_/test_relative_imports.py

@@ -0,0 +1,199 @@
+"""Test relative imports (PEP 328)."""
+
+from ..support import uncache, import_, mock_modules, import_state
+
+import sys
+import unittest
+
+class RelativeImports(unittest.TestCase):
+
+    """PEP 328 introduced relative imports. This allows for imports to occur
+    from within a package without having to specify the actual package name.
+
+    A simple example is to import another module within the same package
+    [module from module]::
+
+      # From pkg.mod1 with pkg.mod2 being a module.
+      from . import mod2
+
+    This also works for getting an attribute from a module that is specified
+    in a relative fashion [attr from module]::
+
+      # From pkg.mod1.
+      from .mod2 import attr
+
+    But this is in no way restricted to working between modules; it works
+    from [package to module],::
+
+      # From pkg, importing pkg.module which is a module.
+      from . import module
+
+    [module to package],::
+
+      # Pull attr from pkg, called from pkg.module which is a module.
+      from . import attr
+
+    and [package to package]::
+
+      # From pkg.subpkg1 (both pkg.subpkg[1,2] are packages).
+      from .. import subpkg2
+
+    The number of dots used is in no way restricted [deep import]::
+
+      # Import pkg.attr from pkg.pkg1.pkg2.pkg3.pkg4.pkg5.
+      from ...... import attr
+
+    To prevent someone from accessing code that is outside of a package, one
+    cannot reach the location containing the root package itself::
+
+      # From pkg.__init__ [too high from package]
+      from .. import top_level
+
+      # From pkg.module [too high from module]
+      from .. import top_level
+
+     Relative imports are the only type of import that allow for an empty
+     module name for an import [empty name].
+
+    """
+
+    def relative_import_test(self, create, globals_, callback):
+        """Abstract out boilerplace for setting up for an import test."""
+        uncache_names = []
+        for name in create:
+            if not name.endswith('.__init__'):
+                uncache_names.append(name)
+            else:
+                uncache_names.append(name[:-len('.__init__')])
+        with mock_modules(*create) as importer:
+            with import_state(meta_path=[importer]):
+                for global_ in globals_:
+                    with uncache(*uncache_names):
+                        callback(global_)
+
+
+    def test_module_from_module(self):
+        # [module from module]
+        create = 'pkg.__init__', 'pkg.mod2'
+        globals_ = {'__package__': 'pkg'}, {'__name__': 'pkg.mod1'}
+        def callback(global_):
+            import_('pkg')  # For __import__().
+            module = import_('', global_, fromlist=['mod2'], level=1)
+            self.assertEqual(module.__name__, 'pkg')
+            self.assert_(hasattr(module, 'mod2'))
+            self.assertEqual(module.mod2.attr, 'pkg.mod2')
+        self.relative_import_test(create, globals_, callback)
+
+    def test_attr_from_module(self):
+        # [attr from module]
+        create = 'pkg.__init__', 'pkg.mod2'
+        globals_ = {'__package__': 'pkg'}, {'__name__': 'pkg.mod1'}
+        def callback(global_):
+            import_('pkg')  # For __import__().
+            module = import_('mod2', global_, fromlist=['attr'], level=1)
+            self.assertEqual(module.__name__, 'pkg.mod2')
+            self.assertEqual(module.attr, 'pkg.mod2')
+        self.relative_import_test(create, globals_, callback)
+
+    def test_package_to_module(self):
+        # [package to module]
+        create = 'pkg.__init__', 'pkg.module'
+        globals_ = ({'__package__': 'pkg'},
+                    {'__name__': 'pkg', '__path__': ['blah']})
+        def callback(global_):
+            import_('pkg')  # For __import__().
+            module = import_('', global_, fromlist=['module'],
+                             level=1)
+            self.assertEqual(module.__name__, 'pkg')
+            self.assert_(hasattr(module, 'module'))
+            self.assertEqual(module.module.attr, 'pkg.module')
+        self.relative_import_test(create, globals_, callback)
+
+    def test_module_to_package(self):
+        # [module to package]
+        create = 'pkg.__init__', 'pkg.module'
+        globals_ = {'__package__': 'pkg'}, {'__name__': 'pkg.module'}
+        def callback(global_):
+            import_('pkg')  # For __import__().
+            module = import_('', global_, fromlist=['attr'], level=1)
+            self.assertEqual(module.__name__, 'pkg')
+        self.relative_import_test(create, globals_, callback)
+
+    def test_package_to_package(self):
+        # [package to package]
+        create = ('pkg.__init__', 'pkg.subpkg1.__init__',
+                    'pkg.subpkg2.__init__')
+        globals_ =  ({'__package__': 'pkg.subpkg1'},
+                     {'__name__': 'pkg.subpkg1', '__path__': ['blah']})
+        def callback(global_):
+            module = import_('', global_, fromlist=['subpkg2'], level=2)
+            self.assertEqual(module.__name__, 'pkg')
+            self.assert_(hasattr(module, 'subpkg2'))
+            self.assertEqual(module.subpkg2.attr, 'pkg.subpkg2.__init__')
+
+    def test_deep_import(self):
+        # [deep import]
+        create = ['pkg.__init__']
+        for count in range(1,6):
+            create.append('{0}.pkg{1}.__init__'.format(
+                            create[-1][:-len('.__init__')], count))
+        globals_ = ({'__package__': 'pkg.pkg1.pkg2.pkg3.pkg4.pkg5'},
+                    {'__name__': 'pkg.pkg1.pkg2.pkg3.pkg4.pkg5',
+                        '__path__': ['blah']})
+        def callback(global_):
+            import_(globals_[0]['__package__'])
+            module = import_('', global_, fromlist=['attr'], level=6)
+            self.assertEqual(module.__name__, 'pkg')
+        self.relative_import_test(create, globals_, callback)
+
+    def test_too_high_from_package(self):
+        # [too high from package]
+        create = ['top_level', 'pkg.__init__']
+        globals_ = ({'__package__': 'pkg'},
+                    {'__name__': 'pkg', '__path__': ['blah']})
+        def callback(global_):
+            import_('pkg')
+            self.assertRaises(ValueError, import_, '', global_,
+                                fromlist=['top_level'], level=2)
+        self.relative_import_test(create, globals_, callback)
+
+    def test_too_high_from_module(self):
+        # [too high from module]
+        create = ['top_level', 'pkg.__init__', 'pkg.module']
+        globals_ = {'__package__': 'pkg'}, {'__name__': 'pkg.module'}
+        def callback(global_):
+            import_('pkg')
+            self.assertRaises(ValueError, import_, '', global_,
+                                fromlist=['top_level'], level=2)
+        self.relative_import_test(create, globals_, callback)
+
+    def test_empty_name_w_level_0(self):
+        # [empty name]
+        self.assertRaises(ValueError, import_, '')
+
+    def test_import_from_different_package(self):
+        # Test importing from a different package than the caller.
+        # in pkg.subpkg1.mod
+        # from ..subpkg2 import mod
+        # XXX
+        create = ['__runpy_pkg__.__init__',
+                    '__runpy_pkg__.__runpy_pkg__.__init__',
+                    '__runpy_pkg__.uncle.__init__',
+                    '__runpy_pkg__.uncle.cousin.__init__',
+                    '__runpy_pkg__.uncle.cousin.nephew']
+        globals_ = {'__package__': '__runpy_pkg__.__runpy_pkg__'}
+        def callback(global_):
+            import_('__runpy_pkg__.__runpy_pkg__')
+            module = import_('uncle.cousin', globals_, {}, fromlist=['nephew'],
+                                level=2)
+            self.assertEqual(module.__name__, '__runpy_pkg__.uncle.cousin')
+        self.relative_import_test(create, globals_, callback)
+
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(RelativeImports)
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/source/__init__.py

@@ -0,0 +1,13 @@
+import importlib.test
+import os.path
+import unittest
+
+
+def test_suite():
+    directory = os.path.dirname(__file__)
+    return importlib.test.test_suite('importlib.test.source', directory)
+
+
+if __name__ == '__main__':
+    from test.support import run_unittest
+    run_unittest(test_suite())

Lib/importlib/test/source/test_case_sensitivity.py

@@ -0,0 +1,57 @@
+"""Test case-sensitivity (PEP 235)."""
+import importlib
+from .. import support
+import os
+import sys
+from test import support as test_support
+import unittest
+
+
+class CaseSensitivityTest(unittest.TestCase):
+
+    """PEP 235 dictates that on case-preserving, case-insensitive file systems
+    that imports are case-sensitive unless the PYTHONCASEOK environment
+    variable is set."""
+
+    name = 'MoDuLe'
+    assert name != name.lower()
+
+    def find(self, path):
+        finder = importlib.PyFileImporter(path)
+        return finder.find_module(self.name)
+
+    def sensitivity_test(self):
+        """Look for a module with matching and non-matching sensitivity."""
+        sensitive_pkg = 'sensitive.{0}'.format(self.name)
+        insensitive_pkg = 'insensitive.{0}'.format(self.name.lower())
+        with support.create_modules(insensitive_pkg, sensitive_pkg) as mapping:
+            sensitive_path = os.path.join(mapping['.root'], 'sensitive')
+            insensitive_path = os.path.join(mapping['.root'], 'insensitive')
+            return self.find(sensitive_path), self.find(insensitive_path)
+
+    def test_sensitive(self):
+        with test_support.EnvironmentVarGuard() as env:
+            env.unset('PYTHONCASEOK')
+            sensitive, insensitive = self.sensitivity_test()
+            self.assert_(hasattr(sensitive, 'load_module'))
+            self.assert_(self.name in sensitive._base_path)
+            self.assert_(insensitive is None)
+
+    def test_insensitive(self):
+        with test_support.EnvironmentVarGuard() as env:
+            env.set('PYTHONCASEOK', '1')
+            sensitive, insensitive = self.sensitivity_test()
+            self.assert_(hasattr(sensitive, 'load_module'))
+            self.assert_(self.name in sensitive._base_path)
+            self.assert_(hasattr(insensitive, 'load_module'))
+            self.assert_(self.name in insensitive._base_path)
+
+
+def test_main():
+    if sys.platform not in ('win32', 'darwin', 'cygwin'):
+        return
+    test_support.run_unittest(CaseSensitivityTest)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/source/test_finder.py

@@ -0,0 +1,130 @@
+import importlib
+from .. import finder_tests
+from .. import support
+import os
+import py_compile
+import unittest
+import warnings
+
+
+class FinderTests(finder_tests.FinderTests):
+
+    """For a top-level module, it should just be found directly in the
+    directory being searched. This is true for a directory with source
+    [top-level source], bytecode [top-level bc], or both [top-level both].
+    There is also the possibility that it is a package [top-level package], in
+    which case there will be a directory with the module name and an
+    __init__.py file. If there is a directory without an __init__.py an
+    ImportWarning is returned [empty dir].
+
+    For sub-modules and sub-packages, the same happens as above but only use
+    the tail end of the name [sub module] [sub package] [sub empty].
+
+    When there is a conflict between a package and module having the same name
+    in the same directory, the package wins out [package over module]. This is
+    so that imports of modules within the package can occur rather than trigger
+    an import error.
+
+    When there is a package and module with the same name, always pick the
+    package over the module [package over module]. This is so that imports from
+    the package have the possibility of succeeding.
+
+    """
+
+    def import_(self, root, module):
+        finder = importlib.PyFileImporter(root)
+        return finder.find_module(module)
+
+    def run_test(self, test, create=None, *, compile_=None, unlink=None):
+        """Test the finding of 'test' with the creation of modules listed in
+        'create'.
+
+        Any names listed in 'compile_' are byte-compiled. Modules
+        listed in 'unlink' have their source files deleted.
+
+        """
+        if create is None:
+            create = {test}
+        with support.create_modules(*create) as mapping:
+            if compile_:
+                for name in compile_:
+                    py_compile.compile(mapping[name])
+            if unlink:
+                for name in unlink:
+                    os.unlink(mapping[name])
+            loader = self.import_(mapping['.root'], test)
+            self.assert_(hasattr(loader, 'load_module'))
+            return loader
+
+    def test_module(self):
+        # [top-level source]
+        self.run_test('top_level')
+        # [top-level bc]
+        self.run_test('top_level', compile_={'top_level'}, unlink={'top_level'})
+        # [top-level both]
+        self.run_test('top_level', compile_={'top_level'})
+
+    # [top-level package]
+    def test_package(self):
+        # Source.
+        self.run_test('pkg', {'pkg.__init__'})
+        # Bytecode.
+        self.run_test('pkg', {'pkg.__init__'}, compile_={'pkg.__init__'},
+                unlink={'pkg.__init__'})
+        # Both.
+        self.run_test('pkg', {'pkg.__init__'}, compile_={'pkg.__init__'})
+
+    # [sub module]
+    def test_module_in_package(self):
+        with support.create_modules('pkg.__init__', 'pkg.sub') as mapping:
+            pkg_dir = os.path.dirname(mapping['pkg.__init__'])
+            loader = self.import_(pkg_dir, 'pkg.sub')
+            self.assert_(hasattr(loader, 'load_module'))
+
+    # [sub package]
+    def test_package_in_package(self):
+        context = support.create_modules('pkg.__init__', 'pkg.sub.__init__')
+        with context as mapping:
+            pkg_dir = os.path.dirname(mapping['pkg.__init__'])
+            loader = self.import_(pkg_dir, 'pkg.sub')
+            self.assert_(hasattr(loader, 'load_module'))
+
+    # [sub empty]
+    def test_empty_sub_directory(self):
+        context = support.create_modules('pkg.__init__', 'pkg.sub.__init__')
+        with warnings.catch_warnings():
+            warnings.simplefilter("error", ImportWarning)
+            with context as mapping:
+                os.unlink(mapping['pkg.sub.__init__'])
+                pkg_dir = os.path.dirname(mapping['pkg.__init__'])
+                self.assertRaises(ImportWarning, self.import_, pkg_dir,
+                                    'pkg.sub')
+
+    # [package over modules]
+    def test_package_over_module(self):
+        # XXX This is not a blackbox test!
+        name = '_temp'
+        loader = self.run_test(name, {'{0}.__init__'.format(name), name})
+        self.assert_('__init__' in loader._base_path)
+
+
+    def test_failure(self):
+        with support.create_modules('blah') as mapping:
+            nothing = self.import_(mapping['.root'], 'sdfsadsadf')
+            self.assert_(nothing is None)
+
+    # [empty dir]
+    def test_empty_dir(self):
+        with warnings.catch_warnings():
+            warnings.simplefilter("error", ImportWarning)
+            self.assertRaises(ImportWarning, self.run_test, 'pkg',
+            {'pkg.__init__'}, unlink={'pkg.__init__'})
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(FinderTests)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/source/test_loader.py

@@ -0,0 +1,201 @@
+import importlib
+from .. import support
+
+import imp
+import os
+import py_compile
+import sys
+import unittest
+
+
+class SimpleTest(unittest.TestCase):
+
+    """Should have no issue importing a source module [basic]. And if there is
+    a syntax error, it should raise a SyntaxError [syntax error].
+
+    """
+
+    # [basic]
+    def test_basic(self):
+        with support.create_modules('_temp') as mapping:
+            loader = importlib._PyFileLoader('_temp', mapping['_temp'], False)
+            loader.load_module('_temp')
+            self.assert_('_temp' in sys.modules)
+
+    # [syntax error]
+    def test_bad_syntax(self):
+        with support.create_modules('_temp') as mapping:
+            with open(mapping['_temp'], 'w') as file:
+                file.write('=')
+            loader = importlib._PyFileLoader('_temp', mapping['_temp'], False)
+            self.assertRaises(SyntaxError, loader.load_module, '_temp')
+            self.assert_('_temp' not in sys.modules)
+
+
+class DontWriteBytecodeTest(unittest.TestCase):
+
+    """If sys.dont_write_bytcode is true then no bytecode should be created."""
+
+    def tearDown(self):
+        sys.dont_write_bytecode = False
+
+    @support.writes_bytecode
+    def run_test(self, assertion):
+        with support.create_modules('_temp') as mapping:
+            loader = importlib._PyFileLoader('_temp', mapping['_temp'], False)
+            loader.load_module('_temp')
+            bytecode_path = support.bytecode_path(mapping['_temp'])
+            assertion(bytecode_path)
+
+    def test_bytecode_written(self):
+        fxn = lambda bc_path: self.assert_(os.path.exists(bc_path))
+        self.run_test(fxn)
+
+    def test_bytecode_not_written(self):
+        sys.dont_write_bytecode = True
+        fxn = lambda bc_path: self.assert_(not os.path.exists(bc_path))
+        self.run_test(fxn)
+
+
+class BadDataTest(unittest.TestCase):
+
+    """If the bytecode has a magic number that does not match the
+    interpreters', ImportError is raised [bad magic]. The timestamp can have
+    any value. And bad marshal data raises ValueError.
+
+    """
+
+    # [bad magic]
+    def test_bad_magic(self):
+        with support.create_modules('_temp') as mapping:
+            py_compile.compile(mapping['_temp'])
+            os.unlink(mapping['_temp'])
+            bytecode_path = support.bytecode_path(mapping['_temp'])
+            with open(bytecode_path, 'r+b') as file:
+                file.seek(0)
+                file.write(b'\x00\x00\x00\x00')
+            loader = importlib._PyFileLoader('_temp', mapping['_temp'], False)
+            self.assertRaises(ImportError, loader.load_module, '_temp')
+            self.assert_('_temp' not in sys.modules)
+
+
+class SourceBytecodeInteraction(unittest.TestCase):
+
+    """When both source and bytecode are present, certain rules dictate which
+    version of the code takes precedent. All things being equal, the bytecode
+    is used with the value of __file__ set to the source [basic top-level],
+    [basic package], [basic sub-module], [basic sub-package].
+
+    """
+
+    def import_(self, file, module, *, pkg=False):
+        loader = importlib._PyFileLoader(module, file, pkg)
+        return loader.load_module(module)
+
+    def run_test(self, test, *create, pkg=False):
+        create += (test,)
+        with support.create_modules(*create) as mapping:
+            for name in create:
+                py_compile.compile(mapping[name])
+            if pkg:
+                import_name = test.rsplit('.', 1)[0]
+            else:
+                import_name = test
+            loader = importlib._PyFileLoader(import_name, mapping[test], pkg)
+            # Because some platforms only have a granularity to the second for
+            # atime you can't check the physical files. Instead just make it an
+            # exception trigger if source was read.
+            loader.get_source = lambda self, x: 42
+            module = loader.load_module(import_name)
+            self.assertEqual(module.__file__, mapping[name])
+            self.assert_(import_name in sys.modules)
+            self.assertEqual(id(module), id(sys.modules[import_name]))
+
+    # [basic top-level]
+    def test_basic_top_level(self):
+        self.run_test('top_level')
+
+    # [basic package]
+    def test_basic_package(self):
+        self.run_test('pkg.__init__', pkg=True)
+
+    # [basic sub-module]
+    def test_basic_sub_module(self):
+        self.run_test('pkg.sub', 'pkg.__init__')
+
+    # [basic sub-package]
+    def test_basic_sub_package(self):
+        self.run_test('pkg.sub.__init__', 'pkg.__init__', pkg=True)
+
+
+class BadBytecodeTest(unittest.TestCase):
+
+    """But there are several things about the bytecode which might lead to the
+    source being preferred. If the magic number differs from what the
+    interpreter uses, then the source is used with the bytecode regenerated.
+    If the timestamp is older than the modification time for the source then
+    the bytecode is not used [bad timestamp].
+
+    But if the marshal data is bad, even if the magic number and timestamp
+    work, a ValueError is raised and the source is not used [bad marshal].
+
+    """
+
+    def import_(self, file, module_name):
+        loader = importlib._PyFileLoader(module_name, file, False)
+        module = loader.load_module(module_name)
+        self.assert_(module_name in sys.modules)
+
+    # [bad magic]
+    @support.writes_bytecode
+    def test_bad_magic(self):
+        with support.create_modules('_temp') as mapping:
+            py_compile.compile(mapping['_temp'])
+            bytecode_path = support.bytecode_path(mapping['_temp'])
+            with open(bytecode_path, 'r+b') as bytecode_file:
+                bytecode_file.seek(0)
+                bytecode_file.write(b'\x00\x00\x00\x00')
+            self.import_(mapping['_temp'], '_temp')
+            with open(bytecode_path, 'rb') as bytecode_file:
+                self.assertEqual(bytecode_file.read(4), imp.get_magic())
+
+    # [bad timestamp]
+    @support.writes_bytecode
+    def test_bad_bytecode(self):
+        zeros = b'\x00\x00\x00\x00'
+        with support.create_modules('_temp') as mapping:
+            py_compile.compile(mapping['_temp'])
+            bytecode_path = support.bytecode_path(mapping['_temp'])
+            with open(bytecode_path, 'r+b') as bytecode_file:
+                bytecode_file.seek(4)
+                bytecode_file.write(zeros)
+            self.import_(mapping['_temp'], '_temp')
+            source_mtime = os.path.getmtime(mapping['_temp'])
+            source_timestamp = importlib._w_long(source_mtime)
+            with open(bytecode_path, 'rb') as bytecode_file:
+                bytecode_file.seek(4)
+                self.assertEqual(bytecode_file.read(4), source_timestamp)
+
+    # [bad marshal]
+    def test_bad_marshal(self):
+        with support.create_modules('_temp') as mapping:
+            bytecode_path = support.bytecode_path(mapping['_temp'])
+            source_mtime = os.path.getmtime(mapping['_temp'])
+            source_timestamp = importlib._w_long(source_mtime)
+            with open(bytecode_path, 'wb') as bytecode_file:
+                bytecode_file.write(imp.get_magic())
+                bytecode_file.write(source_timestamp)
+                bytecode_file.write(b'AAAA')
+            self.assertRaises(ValueError, self.import_, mapping['_temp'],
+                                '_temp')
+            self.assert_('_temp' not in sys.modules)
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(SimpleTest, DontWriteBytecodeTest, BadDataTest,
+                 SourceBytecodeInteraction, BadBytecodeTest)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/source/test_path_hook.py

@@ -0,0 +1,23 @@
+import importlib
+from .. import support
+import unittest
+
+
+class PathHookTest(unittest.TestCase):
+
+    """Test the path hook for source."""
+
+    def test_success(self):
+        # XXX Only work on existing directories?
+        with support.create_modules('dummy') as mapping:
+            self.assert_(hasattr(importlib.FileImporter(mapping['.root']),
+                                 'find_module'))
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(PathHookTest)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/source/test_reload.py

@@ -0,0 +1,71 @@
+"""Test reload support.
+
+Reload support requires two things. One is that if module is loaded that
+already exists in sys.modules then it is reused. And two, if a reload fails the
+pre-existing module is left in a sane state.
+
+"""
+import imp
+import sys
+import types
+import unittest
+import importlib
+from .. import support
+
+
+class ReloadTests(unittest.TestCase):
+
+    name = '_temp'
+
+    def load_module(self, mapping):
+        return importlib._PyFileLoader(self.name, mapping[self.name], False)
+
+    def fake_mtime(self, fxn):
+        """Fake mtime to always be higher than expected."""
+        return lambda name: fxn(name) + 1
+
+    def test_module_reuse(self):
+        with support.create_modules(self.name) as mapping:
+            loader = self.load_module(mapping)
+            module = loader.load_module(self.name)
+            module_id = id(module)
+            module_dict_id = id(module.__dict__)
+            with open(mapping[self.name], 'w') as file:
+                file.write("testing_var = 42\n")
+            # For filesystems where the mtime is only to a second granularity,
+            # everything that has happened above can be too fast;
+            # force an mtime on the source that is guaranteed to be different
+            # than the original mtime.
+            loader.source_mtime = self.fake_mtime(loader.source_mtime)
+            module = loader.load_module(self.name)
+            self.assert_('testing_var' in module.__dict__,
+                         "'testing_var' not in "
+                            "{0}".format(list(module.__dict__.keys())))
+            self.assertEqual(module, sys.modules[self.name])
+            self.assertEqual(id(module), module_id)
+            self.assertEqual(id(module.__dict__), module_dict_id)
+
+    def test_bad_reload(self):
+        # A failed reload should leave the original module intact.
+        attributes = ('__file__', '__path__', '__package__')
+        value = '<test>'
+        with support.create_modules(self.name) as mapping:
+            orig_module = imp.new_module(self.name)
+            for attr in attributes:
+                setattr(orig_module, attr, value)
+            with open(mapping[self.name], 'w') as file:
+                file.write('+++ bad syntax +++')
+            loader = self.load_module(mapping)
+            self.assertRaises(SyntaxError, loader.load_module, self.name)
+            for attr in attributes:
+                self.assertEqual(getattr(orig_module, attr), value)
+
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(ReloadTests)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/source/test_source_encoding.py

@@ -0,0 +1,122 @@
+import importlib
+from .. import support
+
+import codecs
+import re
+import sys
+# Because sys.path gets essentially blanked, need to have unicodedata already
+# imported for the parser to use.
+import unicodedata
+import unittest
+
+
+CODING_RE = re.compile(r'coding[:=]\s*([-\w.]+)')
+
+
+class EncodingTest(unittest.TestCase):
+
+    """PEP 3120 makes UTF-8 the default encoding for source code
+    [default encoding].
+
+    PEP 263 specifies how that can change on a per-file basis. Either the first
+    or second line can contain the encoding line [encoding first line]
+    encoding second line]. If the file has the BOM marker it is considered UTF-8
+    implicitly [BOM]. If any encoding is specified it must be UTF-8, else it is
+    an error [BOM and utf-8][BOM conflict].
+
+    """
+
+    variable = '\u00fc'
+    character = '\u00c9'
+    source_line = "{0} = '{1}'\n".format(variable, character)
+    module_name = '_temp'
+
+    def run_test(self, source):
+        with support.create_modules(self.module_name) as mapping:
+            with open(mapping[self.module_name], 'wb')as file:
+                file.write(source)
+            loader = importlib._PyFileLoader(self.module_name,
+                                       mapping[self.module_name], False)
+            return loader.load_module(self.module_name)
+
+    def create_source(self, encoding):
+        encoding_line = "# coding={0}".format(encoding)
+        assert CODING_RE.search(encoding_line)
+        source_lines = [encoding_line.encode('utf-8')]
+        source_lines.append(self.source_line.encode(encoding))
+        return b'\n'.join(source_lines)
+
+    def test_non_obvious_encoding(self):
+        # Make sure that an encoding that has never been a standard one for
+        # Python works.
+        encoding_line = "# coding=koi8-r"
+        assert CODING_RE.search(encoding_line)
+        source = "{0}\na=42\n".format(encoding_line).encode("koi8-r")
+        self.run_test(source)
+
+    # [default encoding]
+    def test_default_encoding(self):
+        self.run_test(self.source_line.encode('utf-8'))
+
+    # [encoding first line]
+    def test_encoding_on_first_line(self):
+        encoding = 'Latin-1'
+        source = self.create_source(encoding)
+        self.run_test(source)
+
+    # [encoding second line]
+    def test_encoding_on_second_line(self):
+        source = b"#/usr/bin/python\n" + self.create_source('Latin-1')
+        self.run_test(source)
+
+    # [BOM]
+    def test_bom(self):
+        self.run_test(codecs.BOM_UTF8 + self.source_line.encode('utf-8'))
+
+    # [BOM and utf-8]
+    def test_bom_and_utf_8(self):
+        source = codecs.BOM_UTF8 + self.create_source('utf-8')
+        self.run_test(source)
+
+    # [BOM conflict]
+    def test_bom_conflict(self):
+        source = codecs.BOM_UTF8 + self.create_source('latin-1')
+        self.assertRaises(SyntaxError, self.run_test, source)
+
+
+class LineEndingTest(unittest.TestCase):
+
+    r"""Source written with the three types of line endings (\n, \r\n, \r)
+    need to be readable [cr][crlf][lf]."""
+
+    def run_test(self, line_ending):
+        module_name = '_temp'
+        source_lines = [b"a = 42", b"b = -13", b'']
+        source = line_ending.join(source_lines)
+        with support.create_modules(module_name) as mapping:
+            with open(mapping[module_name], 'wb') as file:
+                file.write(source)
+            loader = importlib._PyFileLoader(module_name, mapping[module_name],
+                                                False)
+            return loader.load_module(module_name)
+
+    # [cr]
+    def test_cr(self):
+        self.run_test(b'\r')
+
+    # [crlf]
+    def test_crlf(self):
+        self.run_test(b'\r\n')
+
+    # [lf]
+    def test_lf(self):
+        self.run_test(b'\n')
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(EncodingTest, LineEndingTest)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/importlib/test/support.py

@@ -0,0 +1,223 @@
+from importlib import Import
+
+from contextlib import contextmanager
+from functools import update_wrapper
+import imp
+import os.path
+from test.support import unlink
+import sys
+from tempfile import gettempdir
+
+
+using___import__ = False
+
+def import_(*args, **kwargs):
+    """Delegate to allow for injecting different implementations of import."""
+    if using___import__:
+        return __import__(*args, **kwargs)
+    return Import()(*args, **kwargs)
+
+def importlib_only(fxn):
+    """Decorator to mark which tests are not supported by the current
+    implementation of __import__()."""
+    def inner(*args, **kwargs):
+        if using___import__:
+            return
+        else:
+            return fxn(*args, **kwargs)
+    update_wrapper(inner, fxn)
+    return inner
+
+def writes_bytecode(fxn):
+    """Decorator that returns the function if writing bytecode is enabled, else
+    a stub function that accepts anything and simply returns None."""
+    if sys.dont_write_bytecode:
+        return lambda *args, **kwargs: None
+    else:
+        return fxn
+
+@contextmanager
+def uncache(*names):
+    """Uncache a module from sys.modules.
+
+    A basic sanity check is performed to prevent uncaching modules that either
+    cannot/shouldn't be uncached.
+
+    """
+    for name in names:
+        if name in ('sys', 'marshal', 'imp'):
+            raise ValueError(
+                "cannot uncache {0} as it will break _importlib".format(name))
+        try:
+            del sys.modules[name]
+        except KeyError:
+            pass
+    try:
+        yield
+    finally:
+        for name in names:
+            try:
+                del sys.modules[name]
+            except KeyError:
+                pass
+
+@contextmanager
+def import_state(**kwargs):
+    """Context manager to manage the various importers and stored state in the
+    sys module.
+
+    The 'modules' attribute is not supported as the interpreter state stores a
+    pointer to the dict that the interpreter uses internally;
+    reassigning to sys.modules does not have the desired effect.
+
+    """
+    originals = {}
+    try:
+        for attr, default in (('meta_path', []), ('path', []),
+                              ('path_hooks', []),
+                              ('path_importer_cache', {})):
+            originals[attr] = getattr(sys, attr)
+            if attr in kwargs:
+                new_value = kwargs[attr]
+                del kwargs[attr]
+            else:
+                new_value = default
+            setattr(sys, attr, new_value)
+        if len(kwargs):
+            raise ValueError(
+                    'unrecognized arguments: {0}'.format(kwargs.keys()))
+        yield
+    finally:
+        for attr, value in originals.items():
+            setattr(sys, attr, value)
+
+
+@contextmanager
+def create_modules(*names):
+    """Temporarily create each named module with an attribute (named 'attr')
+    that contains the name passed into the context manager that caused the
+    creation of the module.
+
+    All files are created in a temporary directory specified by
+    tempfile.gettempdir(). This directory is inserted at the beginning of
+    sys.path. When the context manager exits all created files (source and
+    bytecode) are explicitly deleted.
+
+    No magic is performed when creating packages! This means that if you create
+    a module within a package you must also create the package's __init__ as
+    well.
+
+    """
+    source = 'attr = {0!r}'
+    created_paths = []
+    mapping = {}
+    try:
+        temp_dir = gettempdir()
+        mapping['.root'] = temp_dir
+        import_names = set()
+        for name in names:
+            if not name.endswith('__init__'):
+                import_name = name
+            else:
+                import_name = name[:-len('.__init__')]
+            import_names.add(import_name)
+            if import_name in sys.modules:
+                del sys.modules[import_name]
+            name_parts = name.split('.')
+            file_path = temp_dir
+            for directory in name_parts[:-1]:
+                file_path = os.path.join(file_path, directory)
+                if not os.path.exists(file_path):
+                    os.mkdir(file_path)
+                    created_paths.append(file_path)
+            file_path = os.path.join(file_path, name_parts[-1] + '.py')
+            with open(file_path, 'w') as file:
+                file.write(source.format(name))
+            created_paths.append(file_path)
+            mapping[name] = file_path
+        uncache_manager = uncache(*import_names)
+        uncache_manager.__enter__()
+        state_manager = import_state(path=[temp_dir])
+        state_manager.__enter__()
+        yield mapping
+    finally:
+        state_manager.__exit__(None, None, None)
+        uncache_manager.__exit__(None, None, None)
+        # Reverse the order for path removal to unroll directory creation.
+        for path in reversed(created_paths):
+            if file_path.endswith('.py'):
+                unlink(path)
+                unlink(path + 'c')
+                unlink(path + 'o')
+            else:
+                os.rmdir(path)
+
+
+class mock_modules:
+
+    """A mock importer/loader."""
+
+    def __init__(self, *names):
+        self.modules = {}
+        for name in names:
+            if not name.endswith('.__init__'):
+                import_name = name
+            else:
+                import_name = name[:-len('.__init__')]
+            if '.' not in name:
+                package = None
+            elif import_name == name:
+                package = name.rsplit('.', 1)[0]
+            else:
+                package = import_name
+            module = imp.new_module(import_name)
+            module.__loader__ = self
+            module.__file__ = '<mock __file__>'
+            module.__package__ = package
+            module.attr = name
+            if import_name != name:
+                module.__path__ = ['<mock __path__>']
+            self.modules[import_name] = module
+
+    def __getitem__(self, name):
+        return self.modules[name]
+
+    def find_module(self, fullname, path=None):
+        if fullname not in self.modules:
+            return None
+        else:
+            return self
+
+    def load_module(self, fullname):
+        if fullname not in self.modules:
+            raise ImportError
+        else:
+            sys.modules[fullname] = self.modules[fullname]
+            return self.modules[fullname]
+
+    def __enter__(self):
+        self._uncache = uncache(*self.modules.keys())
+        self._uncache.__enter__()
+        return self
+
+    def __exit__(self, *exc_info):
+        self._uncache.__exit__(None, None, None)
+
+
+def mock_path_hook(*entries, importer):
+    """A mock sys.path_hooks entry."""
+    def hook(entry):
+        if entry not in entries:
+            raise ImportError
+        return importer
+    return hook
+
+
+def bytecode_path(source_path):
+    for suffix, _, type_ in imp.get_suffixes():
+        if type_ == imp.PY_COMPILED:
+            bc_suffix = suffix
+            break
+    else:
+        raise ValueError("no bytecode suffix is defined")
+    return os.path.splitext(source_path)[0] + bc_suffix

Lib/importlib/test/test_api.py

@@ -0,0 +1,62 @@
+import unittest
+import importlib
+from . import support
+
+
+class ImportModuleTests(unittest.TestCase):
+
+    """Test importlib.import_module."""
+
+    def test_module_import(self):
+        # Test importing a top-level module.
+        with support.mock_modules('top_level') as mock:
+            with support.import_state(meta_path=[mock]):
+                module = importlib.import_module('top_level')
+                self.assertEqual(module.__name__, 'top_level')
+
+    def test_absolute_package_import(self):
+        # Test importing a module from a package with an absolute name.
+        pkg_name = 'pkg'
+        pkg_long_name = '{0}.__init__'.format(pkg_name)
+        name = '{0}.mod'.format(pkg_name)
+        with support.mock_modules(pkg_long_name, name) as mock:
+            with support.import_state(meta_path=[mock]):
+                module = importlib.import_module(name)
+                self.assertEqual(module.__name__, name)
+
+    def test_relative_package_import(self):
+        # Test importing a module from a package through a relatve import.
+        pkg_name = 'pkg'
+        pkg_long_name = '{0}.__init__'.format(pkg_name)
+        module_name = 'mod'
+        absolute_name = '{0}.{1}'.format(pkg_name, module_name)
+        relative_name = '.{0}'.format(module_name)
+        with support.mock_modules(pkg_long_name, absolute_name) as mock:
+            with support.import_state(meta_path=[mock]):
+                module = importlib.import_module(relative_name, pkg_name)
+                self.assertEqual(module.__name__, absolute_name)
+
+    def test_absolute_import_with_package(self):
+        # Test importing a module from a package with an absolute name with
+        # the 'package' argument given.
+        pkg_name = 'pkg'
+        pkg_long_name = '{0}.__init__'.format(pkg_name)
+        name = '{0}.mod'.format(pkg_name)
+        with support.mock_modules(pkg_long_name, name) as mock:
+            with support.import_state(meta_path=[mock]):
+                module = importlib.import_module(name, pkg_name)
+                self.assertEqual(module.__name__, name)
+
+    def test_relative_import_wo_package(self):
+        # Relative imports cannot happen without the 'package' argument being
+        # set.
+        self.assertRaises(TypeError, importlib.import_module, '.support')
+
+
+def test_main():
+    from test.support import run_unittest
+    run_unittest(ImportModuleTests)
+
+
+if __name__ == '__main__':
+    test_main()

Lib/test/test_importlib.py

@@ -0,0 +1,10 @@
+from test.support import run_unittest
+import importlib.test
+
+
+def test_main():
+    run_unittest(importlib.test.test_suite('importlib.test'))
+
+
+if __name__ == '__main__':
+    test_main()