Speed up test suite via distributed testing (#2196)

[etc/vim.git] / tests / test_black.py

diff --git a/tests/test_black.py b/tests/test_black.py
index a2efef8242287b4194ce5deed1eab650c113623a..b8e526a953eccb7c719b9b29dab81d9bfe5fb5e3 100644 (file)
--- a/tests/test_black.py
+++ b/tests/test_black.py
@@ -24,6 +24,7 @@ from typing import (
     Iterator,
     TypeVar,
 )
     Iterator,
     TypeVar,
 )

+import pytest

 import unittest
 from unittest.mock import patch, MagicMock
 
 import unittest
 from unittest.mock import patch, MagicMock
 


@@ -254,6 +255,24 @@ class BlackTestCase(BlackBaseTestCase):
         actual = fs(source)
         black.assert_stable(source, actual, DEFAULT_MODE)
 
         actual = fs(source)
         black.assert_stable(source, actual, DEFAULT_MODE)
 

+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_trailing_comma_optional_parens_stability1_pass2(self) -> None:
+        source, _expected = read_data("trailing_comma_optional_parens1")
+        actual = fs(fs(source))  # this is what `format_file_contents` does with --safe
+        black.assert_stable(source, actual, DEFAULT_MODE)
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_trailing_comma_optional_parens_stability2_pass2(self) -> None:
+        source, _expected = read_data("trailing_comma_optional_parens2")
+        actual = fs(fs(source))  # this is what `format_file_contents` does with --safe
+        black.assert_stable(source, actual, DEFAULT_MODE)
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_trailing_comma_optional_parens_stability3_pass2(self) -> None:
+        source, _expected = read_data("trailing_comma_optional_parens3")
+        actual = fs(fs(source))  # this is what `format_file_contents` does with --safe
+        black.assert_stable(source, actual, DEFAULT_MODE)
+

     @patch("black.dump_to_file", dump_to_stderr)
     def test_pep_572(self) -> None:
         source, expected = read_data("pep_572")
     @patch("black.dump_to_file", dump_to_stderr)
     def test_pep_572(self) -> None:
         source, expected = read_data("pep_572")


@@ -263,6 +282,23 @@ class BlackTestCase(BlackBaseTestCase):
         if sys.version_info >= (3, 8):
             black.assert_equivalent(source, actual)
 
         if sys.version_info >= (3, 8):
             black.assert_equivalent(source, actual)
 

+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_pep_572_remove_parens(self) -> None:
+        source, expected = read_data("pep_572_remove_parens")
+        actual = fs(source)
+        self.assertFormatEqual(expected, actual)
+        black.assert_stable(source, actual, DEFAULT_MODE)
+        if sys.version_info >= (3, 8):
+            black.assert_equivalent(source, actual)
+
+    @patch("black.dump_to_file", dump_to_stderr)
+    def test_pep_572_do_not_remove_parens(self) -> None:
+        source, expected = read_data("pep_572_do_not_remove_parens")
+        # the AST safety checks will fail, but that's expected, just make sure no
+        # parentheses are touched
+        actual = black.format_str(source, mode=DEFAULT_MODE)
+        self.assertFormatEqual(expected, actual)
+

     def test_pep_572_version_detection(self) -> None:
         source, _ = read_data("pep_572")
         root = black.lib2to3_parse(source)
     def test_pep_572_version_detection(self) -> None:
         source, _ = read_data("pep_572")
         root = black.lib2to3_parse(source)


@@ -287,6 +323,7 @@ class BlackTestCase(BlackBaseTestCase):
 
     def test_expression_diff(self) -> None:
         source, _ = read_data("expression.py")
 
     def test_expression_diff(self) -> None:
         source, _ = read_data("expression.py")

+        config = THIS_DIR / "data" / "empty_pyproject.toml"

         expected, _ = read_data("expression.diff")
         tmp_file = Path(black.dump_to_file(source))
         diff_header = re.compile(
         expected, _ = read_data("expression.diff")
         tmp_file = Path(black.dump_to_file(source))
         diff_header = re.compile(


@@ -294,13 +331,14 @@ class BlackTestCase(BlackBaseTestCase):
             r"\d\d:\d\d:\d\d\.\d\d\d\d\d\d \+\d\d\d\d"
         )
         try:
             r"\d\d:\d\d:\d\d\.\d\d\d\d\d\d \+\d\d\d\d"
         )
         try:

-            result = BlackRunner().invoke(black.main, ["--diff", str(tmp_file)])
+            result = BlackRunner().invoke(
+                black.main, ["--diff", str(tmp_file), f"--config={config}"]
+            )

             self.assertEqual(result.exit_code, 0)
         finally:
             os.unlink(tmp_file)
         actual = result.output
         actual = diff_header.sub(DETERMINISTIC_HEADER, actual)
             self.assertEqual(result.exit_code, 0)
         finally:
             os.unlink(tmp_file)
         actual = result.output
         actual = diff_header.sub(DETERMINISTIC_HEADER, actual)

-        actual = actual.rstrip() + "\n"  # the diff output has a trailing space

         if expected != actual:
             dump = black.dump_to_file(actual)
             msg = (
         if expected != actual:
             dump = black.dump_to_file(actual)
             msg = (


@@ -312,11 +350,12 @@ class BlackTestCase(BlackBaseTestCase):
 
     def test_expression_diff_with_color(self) -> None:
         source, _ = read_data("expression.py")
 
     def test_expression_diff_with_color(self) -> None:
         source, _ = read_data("expression.py")

+        config = THIS_DIR / "data" / "empty_pyproject.toml"

         expected, _ = read_data("expression.diff")
         tmp_file = Path(black.dump_to_file(source))
         try:
             result = BlackRunner().invoke(
         expected, _ = read_data("expression.diff")
         tmp_file = Path(black.dump_to_file(source))
         try:
             result = BlackRunner().invoke(

-                black.main, ["--diff", "--color", str(tmp_file)]
+                black.main, ["--diff", "--color", str(tmp_file), f"--config={config}"]

             )
         finally:
             os.unlink(tmp_file)
             )
         finally:
             os.unlink(tmp_file)


@@ -349,11 +388,12 @@ class BlackTestCase(BlackBaseTestCase):
     @patch("black.dump_to_file", dump_to_stderr)
     def test_string_quotes(self) -> None:
         source, expected = read_data("string_quotes")
     @patch("black.dump_to_file", dump_to_stderr)
     def test_string_quotes(self) -> None:
         source, expected = read_data("string_quotes")

-        actual = fs(source)
+        mode = black.Mode(experimental_string_processing=True)
+        actual = fs(source, mode=mode)

         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(source, actual)

-        black.assert_stable(source, actual, DEFAULT_MODE)
-        mode = replace(DEFAULT_MODE, string_normalization=False)
+        black.assert_stable(source, actual, mode)
+        mode = replace(mode, string_normalization=False)

         not_normalized = fs(source, mode=mode)
         self.assertFormatEqual(source.replace("\\\n", ""), not_normalized)
         black.assert_equivalent(source, not_normalized)
         not_normalized = fs(source, mode=mode)
         self.assertFormatEqual(source.replace("\\\n", ""), not_normalized)
         black.assert_equivalent(source, not_normalized)


@@ -420,6 +460,38 @@ class BlackTestCase(BlackBaseTestCase):
             )
             self.assertEqual(expected, actual, msg)
 
             )
             self.assertEqual(expected, actual, msg)
 

+    @pytest.mark.no_python2
+    def test_python2_should_fail_without_optional_install(self) -> None:
+        if sys.version_info < (3, 8):
+            self.skipTest(
+                "Python 3.6 and 3.7 will install typed-ast to work and as such will be"
+                " able to parse Python 2 syntax without explicitly specifying the"
+                " python2 extra"
+            )
+
+        source = "x = 1234l"
+        tmp_file = Path(black.dump_to_file(source))
+        try:
+            runner = BlackRunner()
+            result = runner.invoke(black.main, [str(tmp_file)])
+            self.assertEqual(result.exit_code, 123)
+        finally:
+            os.unlink(tmp_file)
+        actual = (
+            runner.stderr_bytes.decode()
+            .replace("\n", "")
+            .replace("\\n", "")
+            .replace("\\r", "")
+            .replace("\r", "")
+        )
+        msg = (
+            "The requested source code has invalid Python 3 syntax."
+            "If you are trying to format Python 2 files please reinstall Black"
+            " with the 'python2' extra: `python3 -m pip install black[python2]`."
+        )
+        self.assertIn(msg, actual)
+
+    @pytest.mark.python2

     @patch("black.dump_to_file", dump_to_stderr)
     def test_python2_print_function(self) -> None:
         source, expected = read_data("python2_print_function")
     @patch("black.dump_to_file", dump_to_stderr)
     def test_python2_print_function(self) -> None:
         source, expected = read_data("python2_print_function")


@@ -1338,7 +1410,40 @@ class BlackTestCase(BlackBaseTestCase):
         this_abs = THIS_DIR.resolve()
         sources.extend(
             black.gen_python_files(
         this_abs = THIS_DIR.resolve()
         sources.extend(
             black.gen_python_files(

-                path.iterdir(), this_abs, include, exclude, None, report, gitignore
+                path.iterdir(),
+                this_abs,
+                include,
+                exclude,
+                None,
+                None,
+                report,
+                gitignore,
+            )
+        )
+        self.assertEqual(sorted(expected), sorted(sources))
+
+    def test_gitingore_used_as_default(self) -> None:
+        path = Path(THIS_DIR / "data" / "include_exclude_tests")
+        include = re.compile(r"\.pyi?$")
+        extend_exclude = re.compile(r"/exclude/")
+        src = str(path / "b/")
+        report = black.Report()
+        expected: List[Path] = [
+            path / "b/.definitely_exclude/a.py",
+            path / "b/.definitely_exclude/a.pyi",
+        ]
+        sources = list(
+            black.get_sources(
+                ctx=FakeContext(),
+                src=(src,),
+                quiet=True,
+                verbose=False,
+                include=include,
+                exclude=None,
+                extend_exclude=extend_exclude,
+                force_exclude=None,
+                report=report,
+                stdin_filename=None,

             )
         )
         self.assertEqual(sorted(expected), sorted(sources))
             )
         )
         self.assertEqual(sorted(expected), sorted(sources))


@@ -1360,8 +1465,9 @@ class BlackTestCase(BlackBaseTestCase):
                 src=(src,),
                 quiet=True,
                 verbose=False,
                 src=(src,),
                 quiet=True,
                 verbose=False,

-                include=include,
-                exclude=exclude,
+                include=re.compile(include),
+                exclude=re.compile(exclude),
+                extend_exclude=None,

                 force_exclude=None,
                 report=report,
                 stdin_filename=None,
                 force_exclude=None,
                 report=report,
                 stdin_filename=None,


@@ -1382,8 +1488,9 @@ class BlackTestCase(BlackBaseTestCase):
                 src=(src,),
                 quiet=True,
                 verbose=False,
                 src=(src,),
                 quiet=True,
                 verbose=False,

-                include=include,
-                exclude=exclude,
+                include=re.compile(include),
+                exclude=re.compile(exclude),
+                extend_exclude=None,

                 force_exclude=None,
                 report=report,
                 stdin_filename=None,
                 force_exclude=None,
                 report=report,
                 stdin_filename=None,


@@ -1405,8 +1512,9 @@ class BlackTestCase(BlackBaseTestCase):
                 src=(src,),
                 quiet=True,
                 verbose=False,
                 src=(src,),
                 quiet=True,
                 verbose=False,

-                include=include,
-                exclude=exclude,
+                include=re.compile(include),
+                exclude=re.compile(exclude),
+                extend_exclude=None,

                 force_exclude=None,
                 report=report,
                 stdin_filename=stdin_filename,
                 force_exclude=None,
                 report=report,
                 stdin_filename=stdin_filename,


@@ -1432,8 +1540,37 @@ class BlackTestCase(BlackBaseTestCase):
                 src=(src,),
                 quiet=True,
                 verbose=False,
                 src=(src,),
                 quiet=True,
                 verbose=False,

-                include=include,
-                exclude=exclude,
+                include=re.compile(include),
+                exclude=re.compile(exclude),
+                extend_exclude=None,
+                force_exclude=None,
+                report=report,
+                stdin_filename=stdin_filename,
+            )
+        )
+        self.assertEqual(sorted(expected), sorted(sources))
+
+    @patch("black.find_project_root", lambda *args: THIS_DIR.resolve())
+    def test_get_sources_with_stdin_filename_and_extend_exclude(self) -> None:
+        # Extend exclude shouldn't exclude stdin_filename since it is mimicking the
+        # file being passed directly. This is the same as
+        # test_exclude_for_issue_1572
+        path = THIS_DIR / "data" / "include_exclude_tests"
+        include = ""
+        extend_exclude = r"/exclude/|a\.py"
+        src = "-"
+        report = black.Report()
+        stdin_filename = str(path / "b/exclude/a.py")
+        expected = [Path(f"__BLACK_STDIN_FILENAME__{stdin_filename}")]
+        sources = list(
+            black.get_sources(
+                ctx=FakeContext(),
+                src=(src,),
+                quiet=True,
+                verbose=False,
+                include=re.compile(include),
+                exclude=re.compile(""),
+                extend_exclude=re.compile(extend_exclude),

                 force_exclude=None,
                 report=report,
                 stdin_filename=stdin_filename,
                 force_exclude=None,
                 report=report,
                 stdin_filename=stdin_filename,


@@ -1457,9 +1594,10 @@ class BlackTestCase(BlackBaseTestCase):
                 src=(src,),
                 quiet=True,
                 verbose=False,
                 src=(src,),
                 quiet=True,
                 verbose=False,

-                include=include,
-                exclude="",
-                force_exclude=force_exclude,
+                include=re.compile(include),
+                exclude=re.compile(""),
+                extend_exclude=None,
+                force_exclude=re.compile(force_exclude),

                 report=report,
                 stdin_filename=stdin_filename,
             )
                 report=report,
                 stdin_filename=stdin_filename,
             )


@@ -1499,8 +1637,34 @@ class BlackTestCase(BlackBaseTestCase):
                 mode=DEFAULT_MODE,
                 report=report,
             )
                 mode=DEFAULT_MODE,
                 report=report,
             )

-            fsts.assert_called_once()
-            # __BLACK_STDIN_FILENAME__ should have been striped
+            fsts.assert_called_once_with(
+                fast=True, write_back=black.WriteBack.YES, mode=DEFAULT_MODE
+            )
+            # __BLACK_STDIN_FILENAME__ should have been stripped
+            report.done.assert_called_with(expected, black.Changed.YES)
+
+    def test_reformat_one_with_stdin_filename_pyi(self) -> None:
+        with patch(
+            "black.format_stdin_to_stdout",
+            return_value=lambda *args, **kwargs: black.Changed.YES,
+        ) as fsts:
+            report = MagicMock()
+            p = "foo.pyi"
+            path = Path(f"__BLACK_STDIN_FILENAME__{p}")
+            expected = Path(p)
+            black.reformat_one(
+                path,
+                fast=True,
+                write_back=black.WriteBack.YES,
+                mode=DEFAULT_MODE,
+                report=report,
+            )
+            fsts.assert_called_once_with(
+                fast=True,
+                write_back=black.WriteBack.YES,
+                mode=replace(DEFAULT_MODE, is_pyi=True),
+            )
+            # __BLACK_STDIN_FILENAME__ should have been stripped

             report.done.assert_called_with(expected, black.Changed.YES)
 
     def test_reformat_one_with_stdin_and_existing_path(self) -> None:
             report.done.assert_called_with(expected, black.Changed.YES)
 
     def test_reformat_one_with_stdin_and_existing_path(self) -> None:


@@ -1524,7 +1688,7 @@ class BlackTestCase(BlackBaseTestCase):
                 report=report,
             )
             fsts.assert_called_once()
                 report=report,
             )
             fsts.assert_called_once()

-            # __BLACK_STDIN_FILENAME__ should have been striped
+            # __BLACK_STDIN_FILENAME__ should have been stripped

             report.done.assert_called_with(expected, black.Changed.YES)
 
     def test_gitignore_exclude(self) -> None:
             report.done.assert_called_with(expected, black.Changed.YES)
 
     def test_gitignore_exclude(self) -> None:


@@ -1543,7 +1707,14 @@ class BlackTestCase(BlackBaseTestCase):
         this_abs = THIS_DIR.resolve()
         sources.extend(
             black.gen_python_files(
         this_abs = THIS_DIR.resolve()
         sources.extend(
             black.gen_python_files(

-                path.iterdir(), this_abs, include, exclude, None, report, gitignore
+                path.iterdir(),
+                this_abs,
+                include,
+                exclude,
+                None,
+                None,
+                report,
+                gitignore,

             )
         )
         self.assertEqual(sorted(expected), sorted(sources))
             )
         )
         self.assertEqual(sorted(expected), sorted(sources))


@@ -1564,6 +1735,8 @@ class BlackTestCase(BlackBaseTestCase):
             Path(path / "b/.definitely_exclude/a.pie"),
             Path(path / "b/.definitely_exclude/a.py"),
             Path(path / "b/.definitely_exclude/a.pyi"),
             Path(path / "b/.definitely_exclude/a.pie"),
             Path(path / "b/.definitely_exclude/a.py"),
             Path(path / "b/.definitely_exclude/a.pyi"),

+            Path(path / ".gitignore"),
+            Path(path / "pyproject.toml"),

         ]
         this_abs = THIS_DIR.resolve()
         sources.extend(
         ]
         this_abs = THIS_DIR.resolve()
         sources.extend(


@@ -1573,25 +1746,21 @@ class BlackTestCase(BlackBaseTestCase):
                 empty,
                 re.compile(black.DEFAULT_EXCLUDES),
                 None,
                 empty,
                 re.compile(black.DEFAULT_EXCLUDES),
                 None,

+                None,

                 report,
                 gitignore,
             )
         )
         self.assertEqual(sorted(expected), sorted(sources))
 
                 report,
                 gitignore,
             )
         )
         self.assertEqual(sorted(expected), sorted(sources))
 

-    def test_empty_exclude(self) -> None:
+    def test_extend_exclude(self) -> None:

         path = THIS_DIR / "data" / "include_exclude_tests"
         report = black.Report()
         gitignore = PathSpec.from_lines("gitwildmatch", [])
         path = THIS_DIR / "data" / "include_exclude_tests"
         report = black.Report()
         gitignore = PathSpec.from_lines("gitwildmatch", [])

-        empty = re.compile(r"")

         sources: List[Path] = []
         expected = [
         sources: List[Path] = []
         expected = [

-            Path(path / "b/dont_exclude/a.py"),
-            Path(path / "b/dont_exclude/a.pyi"),

             Path(path / "b/exclude/a.py"),
             Path(path / "b/exclude/a.py"),

-            Path(path / "b/exclude/a.pyi"),
-            Path(path / "b/.definitely_exclude/a.py"),
-            Path(path / "b/.definitely_exclude/a.pyi"),
+            Path(path / "b/dont_exclude/a.py"),

         ]
         this_abs = THIS_DIR.resolve()
         sources.extend(
         ]
         this_abs = THIS_DIR.resolve()
         sources.extend(


@@ -1599,7 +1768,8 @@ class BlackTestCase(BlackBaseTestCase):
                 path.iterdir(),
                 this_abs,
                 re.compile(black.DEFAULT_INCLUDES),
                 path.iterdir(),
                 this_abs,
                 re.compile(black.DEFAULT_INCLUDES),

-                empty,
+                re.compile(r"\.pyi$"),
+                re.compile(r"\.definitely_exclude"),

                 None,
                 report,
                 gitignore,
                 None,
                 report,
                 gitignore,


@@ -1607,8 +1777,8 @@ class BlackTestCase(BlackBaseTestCase):
         )
         self.assertEqual(sorted(expected), sorted(sources))
 
         )
         self.assertEqual(sorted(expected), sorted(sources))
 

-    def test_invalid_include_exclude(self) -> None:
-        for option in ["--include", "--exclude"]:
+    def test_invalid_cli_regex(self) -> None:
+        for option in ["--include", "--exclude", "--extend-exclude", "--force-exclude"]:

             self.invokeBlack(["-", option, "**()(!!*)"], exit_code=2)
 
     def test_preserves_line_endings(self) -> None:
             self.invokeBlack(["-", option, "**()(!!*)"], exit_code=2)
 
     def test_preserves_line_endings(self) -> None:


@@ -1657,7 +1827,14 @@ class BlackTestCase(BlackBaseTestCase):
         try:
             list(
                 black.gen_python_files(
         try:
             list(
                 black.gen_python_files(

-                    path.iterdir(), root, include, exclude, None, report, gitignore
+                    path.iterdir(),
+                    root,
+                    include,
+                    exclude,
+                    None,
+                    None,
+                    report,
+                    gitignore,

                 )
             )
         except ValueError as ve:
                 )
             )
         except ValueError as ve:


@@ -1671,7 +1848,14 @@ class BlackTestCase(BlackBaseTestCase):
         with self.assertRaises(ValueError):
             list(
                 black.gen_python_files(
         with self.assertRaises(ValueError):
             list(
                 black.gen_python_files(

-                    path.iterdir(), root, include, exclude, None, report, gitignore
+                    path.iterdir(),
+                    root,
+                    include,
+                    exclude,
+                    None,
+                    None,
+                    report,
+                    gitignore,

                 )
             )
         path.iterdir.assert_called()
                 )
             )
         path.iterdir.assert_called()


@@ -1776,6 +1960,34 @@ class BlackTestCase(BlackBaseTestCase):
             self.assertEqual(black.find_project_root((src_dir,)), src_dir.resolve())
             self.assertEqual(black.find_project_root((src_python,)), src_dir.resolve())
 
             self.assertEqual(black.find_project_root((src_dir,)), src_dir.resolve())
             self.assertEqual(black.find_project_root((src_python,)), src_dir.resolve())
 

+    @patch("black.find_user_pyproject_toml", black.find_user_pyproject_toml.__wrapped__)
+    def test_find_user_pyproject_toml_linux(self) -> None:
+        if system() == "Windows":
+            return
+
+        # Test if XDG_CONFIG_HOME is checked
+        with TemporaryDirectory() as workspace:
+            tmp_user_config = Path(workspace) / "black"
+            with patch.dict("os.environ", {"XDG_CONFIG_HOME": workspace}):
+                self.assertEqual(
+                    black.find_user_pyproject_toml(), tmp_user_config.resolve()
+                )
+
+        # Test fallback for XDG_CONFIG_HOME
+        with patch.dict("os.environ"):
+            os.environ.pop("XDG_CONFIG_HOME", None)
+            fallback_user_config = Path("~/.config").expanduser() / "black"
+            self.assertEqual(
+                black.find_user_pyproject_toml(), fallback_user_config.resolve()
+            )
+
+    def test_find_user_pyproject_toml_windows(self) -> None:
+        if system() != "Windows":
+            return
+
+        user_config_path = Path.home() / ".black"
+        self.assertEqual(black.find_user_pyproject_toml(), user_config_path.resolve())
+

     def test_bpo_33660_workaround(self) -> None:
         if system() == "Windows":
             return
     def test_bpo_33660_workaround(self) -> None:
         if system() == "Windows":
             return


@@ -1798,6 +2010,49 @@ class BlackTestCase(BlackBaseTestCase):
         output = black.format_str(source, mode=DEFAULT_MODE)
         black.assert_stable(source, output, mode=DEFAULT_MODE)
 
         output = black.format_str(source, mode=DEFAULT_MODE)
         black.assert_stable(source, output, mode=DEFAULT_MODE)
 

+    def test_bpo_2142_workaround(self) -> None:
+
+        # https://bugs.python.org/issue2142
+
+        source, _ = read_data("missing_final_newline.py")
+        # read_data adds a trailing newline
+        source = source.rstrip()
+        expected, _ = read_data("missing_final_newline.diff")
+        tmp_file = Path(black.dump_to_file(source, ensure_final_newline=False))
+        diff_header = re.compile(
+            rf"{re.escape(str(tmp_file))}\t\d\d\d\d-\d\d-\d\d "
+            r"\d\d:\d\d:\d\d\.\d\d\d\d\d\d \+\d\d\d\d"
+        )
+        try:
+            result = BlackRunner().invoke(black.main, ["--diff", str(tmp_file)])
+            self.assertEqual(result.exit_code, 0)
+        finally:
+            os.unlink(tmp_file)
+        actual = result.output
+        actual = diff_header.sub(DETERMINISTIC_HEADER, actual)
+        self.assertEqual(actual, expected)
+
+    @pytest.mark.python2
+    def test_docstring_reformat_for_py27(self) -> None:
+        """
+        Check that stripping trailing whitespace from Python 2 docstrings
+        doesn't trigger a "not equivalent to source" error
+        """
+        source = (
+            b'def foo():\r\n    """Testing\r\n    Testing """\r\n    print "Foo"\r\n'
+        )
+        expected = 'def foo():\n    """Testing\n    Testing"""\n    print "Foo"\n'
+
+        result = CliRunner().invoke(
+            black.main,
+            ["-", "-q", "--target-version=py27"],
+            input=BytesIO(source),
+        )
+
+        self.assertEqual(result.exit_code, 0)
+        actual = result.output
+        self.assertFormatEqual(actual, expected)
+

 
 with open(black.__file__, "r", encoding="utf-8") as _bf:
     black_source_lines = _bf.readlines()
 
 with open(black.__file__, "r", encoding="utf-8") as _bf:
     black_source_lines = _bf.readlines()