cpython/Demo/parser/test_unparse.py

import unittest
import test.support

import io
import ast
import _ast
import unparse

for_else = """\
def f():
    for x in range(10):
        break
    else:
        y = 2
    z = 3
"""

while_else = """\
def g():
    while True:
        break
    else:
        y = 2
    z = 3
"""

relative_import = """\
from . import fred
from .. import barney
from .australia import shrimp as prawns
"""

nonlocal_ex = """\
def f():
    x = 1
    def g():
        nonlocal x
        x = 2
        y = 7
        def h():
            nonlocal x, y
"""

# also acts as test for 'except ... as ...'
raise_from = """\
try:
    1 / 0
except ZeroDivisionError as e:
    raise ArithmeticError from e
"""

class_decorator = """\
@f1(arg)
@f2
class Foo: pass
"""

class UnparseTestCase(unittest.TestCase):
    # Tests for specific bugs found in earlier versions of unparse

    def check_roundtrip(self, code1, filename="internal"):
        ast1 = compile(code1, filename, "exec", _ast.PyCF_ONLY_AST)
        unparse_buffer = io.StringIO()
        unparse.Unparser(ast1, unparse_buffer)
        code2 = unparse_buffer.getvalue()
        ast2 = compile(code2, filename, "exec", _ast.PyCF_ONLY_AST)
        self.assertEqual(ast.dump(ast1), ast.dump(ast2))

    def test_del_statement(self):
        self.check_roundtrip("del x, y, z")

    def test_shifts(self):
        self.check_roundtrip("45 << 2")
        self.check_roundtrip("13 >> 7")

    def test_for_else(self):
        self.check_roundtrip(for_else)

    def test_while_else(self):
        self.check_roundtrip(while_else)

    def test_unary_parens(self):
        self.check_roundtrip("(-1)**7")
        self.check_roundtrip("not True or False")
        self.check_roundtrip("True or not False")

    def test_chained_comparisons(self):
        self.check_roundtrip("1 < 4 <= 5")
        self.check_roundtrip("a is b is c is not d")

    def test_function_arguments(self):
        self.check_roundtrip("def f(): pass")
        self.check_roundtrip("def f(a): pass")
        self.check_roundtrip("def f(b = 2): pass")
        self.check_roundtrip("def f(a, b): pass")
        self.check_roundtrip("def f(a, b = 2): pass")
        self.check_roundtrip("def f(a = 5, b = 2): pass")
        self.check_roundtrip("def f(*, a = 1, b = 2): pass")
        self.check_roundtrip("def f(*, a = 1, b): pass")
        self.check_roundtrip("def f(*, a, b = 2): pass")
        self.check_roundtrip("def f(a, b = None, *, c, **kwds): pass")
        self.check_roundtrip("def f(a=2, *args, c=5, d, **kwds): pass")
        self.check_roundtrip("def f(*args, **kwargs): pass")

    def test_relative_import(self):
        self.check_roundtrip(relative_import)

    def test_nonlocal(self):
        self.check_roundtrip(nonlocal_ex)

    def test_raise_from(self):
        self.check_roundtrip(raise_from)

    def test_bytes(self):
        self.check_roundtrip("b'123'")

    def test_annotations(self):
        self.check_roundtrip("def f(a : int): pass")
        self.check_roundtrip("def f(a: int = 5): pass")
        self.check_roundtrip("def f(*args: [int]): pass")
        self.check_roundtrip("def f(**kwargs: dict): pass")
        self.check_roundtrip("def f() -> None: pass")

    def test_set_literal(self):
        self.check_roundtrip("{'a', 'b', 'c'}")

    def test_set_comprehension(self):
        self.check_roundtrip("{x for x in range(5)}")

    def test_dict_comprehension(self):
        self.check_roundtrip("{x: x*x for x in range(10)}")

    def test_class_decorators(self):
        self.check_roundtrip(class_decorator)

def test_main():
    test.support.run_unittest(UnparseTestCase)

if __name__ == '__main__':
    test_main()