bpo-38870: Expose a function to unparse an ast object in the ast module (GH-17302)

Add ast.unparse() as a function in the ast module that can be used to unparse an
ast.AST object and produce a string with code that would produce an equivalent ast.AST
object when parsed.

1 files changed, 0 insertions, 318 deletions

diff --git a/Lib/test/test_tools/test_unparse.py b/Lib/test/test_tools/test_unparse.py
deleted file mode 100644
index a958ebb..0000000
--- a/Lib/test/test_tools/test_unparse.py
+++ /dev/null
@@ -1,318 +0,0 @@
-"""Tests for the unparse.py script in the Tools/parser directory."""
-
-import unittest
-import test.support
-import io
-import os
-import random
-import tokenize
-import ast
-
-from test.test_tools import basepath, toolsdir, skip_if_missing
-
-skip_if_missing()
-
-parser_path = os.path.join(toolsdir, "parser")
-
-with test.support.DirsOnSysPath(parser_path):
-    import unparse
-
-def read_pyfile(filename):
-    """Read and return the contents of a Python source file (as a
-    string), taking into account the file encoding."""
-    with open(filename, "rb") as pyfile:
-        encoding = tokenize.detect_encoding(pyfile.readline)[0]
-    with open(filename, "r", encoding=encoding) as pyfile:
-        source = pyfile.read()
-    return source
-
-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
-"""
-
-elif1 = """\
-if cond1:
-    suite1
-elif cond2:
-    suite2
-else:
-    suite3
-"""
-
-elif2 = """\
-if cond1:
-    suite1
-elif cond2:
-    suite2
-"""
-
-try_except_finally = """\
-try:
-    suite1
-except ex1:
-    suite2
-except ex2:
-    suite3
-else:
-    suite4
-finally:
-    suite5
-"""
-
-with_simple = """\
-with f():
-    suite1
-"""
-
-with_as = """\
-with f() as x:
-    suite1
-"""
-
-with_two_items = """\
-with f() as x, g() as y:
-    suite1
-"""
-
-class ASTTestCase(unittest.TestCase):
-    def assertASTEqual(self, ast1, ast2):
-        self.assertEqual(ast.dump(ast1), ast.dump(ast2))
-
-    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.assertASTEqual(ast1, ast2)
-
-class UnparseTestCase(ASTTestCase):
-    # Tests for specific bugs found in earlier versions of unparse
-
-    def test_fstrings(self):
-        # See issue 25180
-        self.check_roundtrip(r"""f'{f"{0}"*3}'""")
-        self.check_roundtrip(r"""f'{f"{y}"*3}'""")
-
-    def test_strings(self):
-        self.check_roundtrip("u'foo'")
-        self.check_roundtrip("r'foo'")
-        self.check_roundtrip("b'foo'")
-
-    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("(-1.)**8")
-        self.check_roundtrip("(-1j)**6")
-        self.check_roundtrip("not True or False")
-        self.check_roundtrip("True or not False")
-
-    def test_integer_parens(self):
-        self.check_roundtrip("3 .__abs__()")
-
-    def test_huge_float(self):
-        self.check_roundtrip("1e1000")
-        self.check_roundtrip("-1e1000")
-        self.check_roundtrip("1e1000j")
-        self.check_roundtrip("-1e1000j")
-
-    def test_min_int(self):
-        self.check_roundtrip(str(-2**31))
-        self.check_roundtrip(str(-2**63))
-
-    def test_imaginary_literals(self):
-        self.check_roundtrip("7j")
-        self.check_roundtrip("-7j")
-        self.check_roundtrip("0j")
-        self.check_roundtrip("-0j")
-
-    def test_lambda_parentheses(self):
-        self.check_roundtrip("(lambda: int)()")
-
-    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_class_definition(self):
-        self.check_roundtrip("class A(metaclass=type, *[], **{}): pass")
-
-    def test_elifs(self):
-        self.check_roundtrip(elif1)
-        self.check_roundtrip(elif2)
-
-    def test_try_except_finally(self):
-        self.check_roundtrip(try_except_finally)
-
-    def test_starred_assignment(self):
-        self.check_roundtrip("a, *b, c = seq")
-        self.check_roundtrip("a, (*b, c) = seq")
-        self.check_roundtrip("a, *b[0], c = seq")
-        self.check_roundtrip("a, *(b, c) = seq")
-
-    def test_with_simple(self):
-        self.check_roundtrip(with_simple)
-
-    def test_with_as(self):
-        self.check_roundtrip(with_as)
-
-    def test_with_two_items(self):
-        self.check_roundtrip(with_two_items)
-
-    def test_dict_unpacking_in_dict(self):
-        # See issue 26489
-        self.check_roundtrip(r"""{**{'y': 2}, 'x': 1}""")
-        self.check_roundtrip(r"""{**{'y': 2}, **{'x': 1}}""")
-
-
-class DirectoryTestCase(ASTTestCase):
-    """Test roundtrip behaviour on all files in Lib and Lib/test."""
-    NAMES = None
-
-    # test directories, relative to the root of the distribution
-    test_directories = 'Lib', os.path.join('Lib', 'test')
-
-    @classmethod
-    def get_names(cls):
-        if cls.NAMES is not None:
-            return cls.NAMES
-
-        names = []
-        for d in cls.test_directories:
-            test_dir = os.path.join(basepath, d)
-            for n in os.listdir(test_dir):
-                if n.endswith('.py') and not n.startswith('bad'):
-                    names.append(os.path.join(test_dir, n))
-
-        # Test limited subset of files unless the 'cpu' resource is specified.
-        if not test.support.is_resource_enabled("cpu"):
-            names = random.sample(names, 10)
-        # bpo-31174: Store the names sample to always test the same files.
-        # It prevents false alarms when hunting reference leaks.
-        cls.NAMES = names
-        return names
-
-    def test_files(self):
-        # get names of files to test
-        names = self.get_names()
-
-        for filename in names:
-            if test.support.verbose:
-                print('Testing %s' % filename)
-
-            # Some f-strings are not correctly round-tripped by
-            #  Tools/parser/unparse.py.  See issue 28002 for details.
-            #  We need to skip files that contain such f-strings.
-            if os.path.basename(filename) in ('test_fstring.py', ):
-                if test.support.verbose:
-                    print(f'Skipping {filename}: see issue 28002')
-                continue
-
-            with self.subTest(filename=filename):
-                source = read_pyfile(filename)
-                self.check_roundtrip(source)
-
-
-if __name__ == '__main__':
-    unittest.main()