cpython/Lib/test/test_funcattrs.py

from test.test_support import verbose, TestFailed, verify
import types

class F:
    def a(self):
        pass

def b():
    'my docstring'
    pass

# __module__ is a special attribute
verify(b.__module__ == __name__)
verify(verify.__module__ == "test.test_support")

# setting attributes on functions
try:
    b.publish
except AttributeError: pass
else: raise TestFailed('expected AttributeError')

if b.__dict__ != {}:
    raise TestFailed('expected unassigned func.__dict__ to be {}')

b.publish = 1
if b.publish != 1:
    raise TestFailed('function attribute not set to expected value')

docstring = 'its docstring'
b.__doc__ = docstring
if b.__doc__ != docstring:
    raise TestFailed('problem with setting __doc__ attribute')

if 'publish' not in dir(b):
    raise TestFailed('attribute not in dir()')

try:
    del b.__dict__
except TypeError: pass
else: raise TestFailed('del func.__dict__ expected TypeError')

b.publish = 1
try:
    b.__dict__ = None
except TypeError: pass
else: raise TestFailed('func.__dict__ = None expected TypeError')

d = {'hello': 'world'}
b.__dict__ = d
if b.__dict__ is not d:
    raise TestFailed('func.__dict__ assignment to dictionary failed')
if b.hello != 'world':
    raise TestFailed('attribute after func.__dict__ assignment failed')

f1 = F()
f2 = F()

try:
    F.a.publish
except AttributeError: pass
else: raise TestFailed('expected AttributeError')

try:
    f1.a.publish
except AttributeError: pass
else: raise TestFailed('expected AttributeError')

# In Python 2.1 beta 1, we disallowed setting attributes on unbound methods
# (it was already disallowed on bound methods).  See the PEP for details.
# In Python 3.0 unbound methods are gone.
F.a.publish = 1

if F.a.publish != 1:
    raise TestFailed('unbound method attribute not set to expected value')

if f1.a.publish != 1:
    raise TestFailed('bound method attribute access did not work')

if f2.a.publish != 1:
    raise TestFailed('bound method attribute access did not work')

if 'publish' not in dir(F.a):
    raise TestFailed('attribute not in dir()')

try:
    f1.a.publish = 0
except (AttributeError, TypeError): pass
else: raise TestFailed('expected AttributeError or TypeError')

# try setting __dict__
F.a.__dict__ = {'one': 11, 'two': 22, 'three': 33}

if f1.a.two != 22:
    raise TestFailed('setting __dict__')

from UserDict import UserDict
d = UserDict({'four': 44, 'five': 55})

try:
    F.a.__dict__ = d
except (AttributeError, TypeError): pass
else: raise TestFailed

if f2.a.one != f1.a.one != F.a.one != 11:
    raise TestFailed

# im_func may not be a Python method!
import new
F.id = new.instancemethod(id, None, F)

eff = F()
if eff.id() != id(eff):
    raise TestFailed

try:
    F.id.foo
except AttributeError: pass
else: raise TestFailed

try:
    F.id.foo = 12
except (AttributeError, TypeError): pass
else: raise TestFailed

try:
    F.id.foo
except AttributeError: pass
else: raise TestFailed

try:
    eff.id.foo
except AttributeError: pass
else: raise TestFailed

try:
    eff.id.foo = 12
except (AttributeError, TypeError): pass
else: raise TestFailed

try:
    eff.id.foo
except AttributeError: pass
else: raise TestFailed

# Regression test for a crash in pre-2.1a1
def another():
    pass

try:
    del another.__dict__
except TypeError: pass
else: raise TestFailed

try:
    del another.__dict__
except TypeError: pass
else: raise TestFailed

try:
    another.__dict__ = None
except TypeError: pass
else: raise TestFailed

try:
    del another.bar
except AttributeError: pass
else: raise TestFailed

# This isn't specifically related to function attributes, but it does test a
# core dump regression in funcobject.c
del another.__defaults__

def foo():
    pass

def bar():
    pass

def temp():
    print(1)

if foo==bar:
    raise TestFailed

d={}
d[foo] = 1

foo.__code__ = temp.__code__

d[foo]

# Test all predefined function attributes systematically

def cantset(obj, name, value, exception=(AttributeError, TypeError)):
    verify(hasattr(obj, name)) # Otherwise it's probably a typo
    try:
        setattr(obj, name, value)
    except exception:
        pass
    else:
        raise TestFailed("shouldn't be able to set %s to %r" % (name, value))
    try:
        delattr(obj, name)
    except (AttributeError, TypeError):
        pass
    else:
        raise TestFailed("shouldn't be able to del %s" % name)

def test_func_closure():
    a = 12
    def f(): print(a)
    c = f.__closure__
    verify(isinstance(c, tuple))
    verify(len(c) == 1)
    verify(c[0].__class__.__name__ == "cell") # don't have a type object handy
    cantset(f, "__closure__", c)

def test_empty_cell():
    def f(): print(a)
    try:
        f.__closure__[0].cell_contents
    except ValueError:
        pass
    else:
        raise TestFailed("shouldn't be able to read an empty cell")

    a = 12

def test_func_doc():
    def f(): pass
    verify(f.__doc__ is None)
    f.__doc__ = "hello"
    verify(f.__doc__ == "hello")
    del f.__doc__
    verify(f.__doc__ is None)

def test_func_globals():
    def f(): pass
    verify(f.__globals__ is globals())
    cantset(f, "__globals__", globals())

def test_func_name():
    def f(): pass
    verify(f.__name__ == "f")
    f.__name__ = "g"
    verify(f.__name__ == "g")
    cantset(f, "__globals__", 1)
    cantset(f, "__name__", 1)
    # test that you can access func.__name__ in restricted mode
    s = """def f(): pass\nf.__name__"""
    exec(s, {'__builtins__':{}})


def test_func_code():
    a = b = 24
    def f(): pass
    def g(): print(12)
    def f1(): print(a)
    def g1(): print(b)
    def f2(): print(a, b)
    verify(type(f.__code__) is types.CodeType)
    f.__code__ = g.__code__
    cantset(f, "__code__", None)
    # can't change the number of free vars
    cantset(f,  "__code__", f1.__code__, exception=ValueError)
    cantset(f1, "__code__",  f.__code__, exception=ValueError)
    cantset(f1, "__code__", f2.__code__, exception=ValueError)
    f1.__code__ = g1.__code__

def test_func_defaults():
    def f(a, b): return (a, b)
    verify(f.__defaults__ is None)
    f.__defaults__ = (1, 2)
    verify(f.__defaults__ == (1, 2))
    verify(f(10) == (10, 2))
    def g(a=1, b=2): return (a, b)
    verify(g.__defaults__ == (1, 2))
    del g.__defaults__
    verify(g.__defaults__ is None)
    try:
        g()
    except TypeError:
        pass
    else:
        raise TestFailed("shouldn't be allowed to call g() w/o defaults")

def test_func_dict():
    def f(): pass
    a = f.__dict__
    verify(a == {})
    f.hello = 'world'
    verify(a == {'hello': 'world'})
    verify(a is f.__dict__)
    f.__dict__ = {'world': 'hello'}
    verify(f.world == "hello")
    verify(f.__dict__ == {'world': 'hello'})
    cantset(f, "__dict__", None)

def test_im_class():
    class C:
        def foo(self): pass
    #verify(C.foo.im_class is C)
    verify(C().foo.im_class is C)
    #cantset(C.foo, "im_class", C)
    cantset(C().foo, "im_class", C)

def test_im_func():
    def foo(self): pass
    class C:
        pass
    C.foo = foo
    #verify(C.foo.im_func is foo)
    verify(C().foo.im_func is foo)
    #cantset(C.foo, "im_func", foo)
    cantset(C().foo, "im_func", foo)

def test_im_self():
    class C:
        def foo(self): pass
    #verify(C.foo.im_self is None)
    c = C()
    #verify(c.foo.im_self is c)
    #cantset(C.foo, "im_self", None)
    #cantset(c.foo, "im_self", c)

def test_im_dict():
    class C:
        def foo(self): pass
        foo.bar = 42
    verify(C.foo.__dict__ == {'bar': 42})
    verify(C().foo.__dict__ == {'bar': 42})
    #cantset(C.foo, "__dict__", C.foo.__dict__)
    #cantset(C().foo, "__dict__", C.foo.__dict__)

def test_im_doc():
    class C:
        def foo(self): "hello"
    verify(C.foo.__doc__ == "hello")
    verify(C().foo.__doc__ == "hello")
    #cantset(C.foo, "__doc__", "hello")
    #cantset(C().foo, "__doc__", "hello")

def test_im_name():
    class C:
        def foo(self): pass
    verify(C.foo.__name__ == "foo")
    verify(C().foo.__name__ == "foo")
    #cantset(C.foo, "__name__", "foo")
    #cantset(C().foo, "__name__", "foo")

def testmore():
    test_func_closure()
    test_empty_cell()
    test_func_doc()
    test_func_globals()
    test_func_name()
    test_func_code()
    test_func_defaults()
    test_func_dict()
    # Tests for instance method attributes
    test_im_class()
    test_im_func()
    test_im_self()
    test_im_dict()
    test_im_doc()
    test_im_name()

testmore()