Bump docker/setup-buildx-action from 2 to 3 (#3892)

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

diff --git a/tests/test_black.py b/tests/test_black.py
index dee6ead50d04567412eee84df1cc3df57b0f10a1..d22b6859607a0ed059c553a76ecbd253ea6e0566 100644 (file)
--- a/tests/test_black.py
+++ b/tests/test_black.py
@@ -41,7 +41,7 @@ import black
 import black.files
 from black import Feature, TargetVersion
 from black import re_compile_maybe_verbose as compile_pattern
 import black.files
 from black import Feature, TargetVersion
 from black import re_compile_maybe_verbose as compile_pattern

-from black.cache import get_cache_dir, get_cache_file
+from black.cache import FileData, get_cache_dir, get_cache_file

 from black.debug import DebugVisitor
 from black.output import color_diff, diff
 from black.report import Report
 from black.debug import DebugVisitor
 from black.output import color_diff, diff
 from black.report import Report


@@ -492,9 +492,7 @@ class BlackTestCase(BlackBaseTestCase):
         project_root = Path(THIS_DIR / "data" / "nested_gitignore_tests")
         working_directory = project_root / "root"
         target_abspath = working_directory / "child"
         project_root = Path(THIS_DIR / "data" / "nested_gitignore_tests")
         working_directory = project_root / "root"
         target_abspath = working_directory / "child"

-        target_contents = (
-            src.relative_to(working_directory) for src in target_abspath.iterdir()
-        )
+        target_contents = list(target_abspath.iterdir())

 
         def mock_n_calls(responses: List[bool]) -> Callable[[], bool]:
             def _mocked_calls() -> bool:
 
         def mock_n_calls(responses: List[bool]) -> Callable[[], bool]:
             def _mocked_calls() -> bool:


@@ -507,11 +505,11 @@ class BlackTestCase(BlackBaseTestCase):
         with patch("pathlib.Path.iterdir", return_value=target_contents), patch(
             "pathlib.Path.cwd", return_value=working_directory
         ), patch("pathlib.Path.is_dir", side_effect=mock_n_calls([True])):
         with patch("pathlib.Path.iterdir", return_value=target_contents), patch(
             "pathlib.Path.cwd", return_value=working_directory
         ), patch("pathlib.Path.is_dir", side_effect=mock_n_calls([True])):

-            ctx = FakeContext()
-            ctx.obj["root"] = project_root
+            # Note that the root folder (project_root) isn't the folder
+            # named "root" (aka working_directory)

             report = MagicMock(verbose=True)
             black.get_sources(
             report = MagicMock(verbose=True)
             black.get_sources(

-                ctx=ctx,
+                root=project_root,

                 src=("./child",),
                 quiet=False,
                 verbose=True,
                 src=("./child",),
                 quiet=False,
                 verbose=True,


@@ -527,7 +525,7 @@ class BlackTestCase(BlackBaseTestCase):
             for _, mock_args, _ in report.path_ignored.mock_calls
         ), "A symbolic link was reported."
         report.path_ignored.assert_called_once_with(
             for _, mock_args, _ in report.path_ignored.mock_calls
         ), "A symbolic link was reported."
         report.path_ignored.assert_called_once_with(

-            Path("child", "b.py"), "matches a .gitignore file content"
+            Path("root", "child", "b.py"), "matches a .gitignore file content"

         )
 
     def test_report_verbose(self) -> None:
         )
 
     def test_report_verbose(self) -> None:


@@ -1119,10 +1117,10 @@ class BlackTestCase(BlackBaseTestCase):
             self.invokeBlack([str(path), "--pyi"])
             actual = path.read_text(encoding="utf-8")
             # verify cache with --pyi is separate
             self.invokeBlack([str(path), "--pyi"])
             actual = path.read_text(encoding="utf-8")
             # verify cache with --pyi is separate

-            pyi_cache = black.read_cache(pyi_mode)
-            self.assertIn(str(path), pyi_cache)
-            normal_cache = black.read_cache(DEFAULT_MODE)
-            self.assertNotIn(str(path), normal_cache)
+            pyi_cache = black.Cache.read(pyi_mode)
+            assert not pyi_cache.is_changed(path)
+            normal_cache = black.Cache.read(DEFAULT_MODE)
+            assert normal_cache.is_changed(path)

         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(contents, actual)
         black.assert_stable(contents, actual, pyi_mode)
         self.assertFormatEqual(expected, actual)
         black.assert_equivalent(contents, actual)
         black.assert_stable(contents, actual, pyi_mode)


@@ -1144,11 +1142,11 @@ class BlackTestCase(BlackBaseTestCase):
                 actual = path.read_text(encoding="utf-8")
                 self.assertEqual(actual, expected)
             # verify cache with --pyi is separate
                 actual = path.read_text(encoding="utf-8")
                 self.assertEqual(actual, expected)
             # verify cache with --pyi is separate

-            pyi_cache = black.read_cache(pyi_mode)
-            normal_cache = black.read_cache(reg_mode)
+            pyi_cache = black.Cache.read(pyi_mode)
+            normal_cache = black.Cache.read(reg_mode)

             for path in paths:
             for path in paths:

-                self.assertIn(str(path), pyi_cache)
-                self.assertNotIn(str(path), normal_cache)
+                assert not pyi_cache.is_changed(path)
+                assert normal_cache.is_changed(path)

 
     def test_pipe_force_pyi(self) -> None:
         source, expected = read_data("miscellaneous", "force_pyi")
 
     def test_pipe_force_pyi(self) -> None:
         source, expected = read_data("miscellaneous", "force_pyi")


@@ -1169,10 +1167,10 @@ class BlackTestCase(BlackBaseTestCase):
             self.invokeBlack([str(path), *PY36_ARGS])
             actual = path.read_text(encoding="utf-8")
             # verify cache with --target-version is separate
             self.invokeBlack([str(path), *PY36_ARGS])
             actual = path.read_text(encoding="utf-8")
             # verify cache with --target-version is separate

-            py36_cache = black.read_cache(py36_mode)
-            self.assertIn(str(path), py36_cache)
-            normal_cache = black.read_cache(reg_mode)
-            self.assertNotIn(str(path), normal_cache)
+            py36_cache = black.Cache.read(py36_mode)
+            assert not py36_cache.is_changed(path)
+            normal_cache = black.Cache.read(reg_mode)
+            assert normal_cache.is_changed(path)

         self.assertEqual(actual, expected)
 
     @event_loop()
         self.assertEqual(actual, expected)
 
     @event_loop()


@@ -1192,11 +1190,11 @@ class BlackTestCase(BlackBaseTestCase):
                 actual = path.read_text(encoding="utf-8")
                 self.assertEqual(actual, expected)
             # verify cache with --target-version is separate
                 actual = path.read_text(encoding="utf-8")
                 self.assertEqual(actual, expected)
             # verify cache with --target-version is separate

-            pyi_cache = black.read_cache(py36_mode)
-            normal_cache = black.read_cache(reg_mode)
+            pyi_cache = black.Cache.read(py36_mode)
+            normal_cache = black.Cache.read(reg_mode)

             for path in paths:
             for path in paths:

-                self.assertIn(str(path), pyi_cache)
-                self.assertNotIn(str(path), normal_cache)
+                assert not pyi_cache.is_changed(path)
+                assert normal_cache.is_changed(path)

 
     def test_pipe_force_py36(self) -> None:
         source, expected = read_data("miscellaneous", "force_py36")
 
     def test_pipe_force_py36(self) -> None:
         source, expected = read_data("miscellaneous", "force_py36")


@@ -1455,30 +1453,6 @@ class BlackTestCase(BlackBaseTestCase):
         with self.assertRaises(AssertionError):
             black.assert_equivalent("{}", "None")
 
         with self.assertRaises(AssertionError):
             black.assert_equivalent("{}", "None")
 

-    def test_shhh_click(self) -> None:
-        try:
-            from click import _unicodefun  # type: ignore
-        except ImportError:
-            self.skipTest("Incompatible Click version")
-
-        if not hasattr(_unicodefun, "_verify_python_env"):
-            self.skipTest("Incompatible Click version")
-
-        # First, let's see if Click is crashing with a preferred ASCII charset.
-        with patch("locale.getpreferredencoding") as gpe:
-            gpe.return_value = "ASCII"
-            with self.assertRaises(RuntimeError):
-                _unicodefun._verify_python_env()
-        # Now, let's silence Click...
-        black.patch_click()
-        # ...and confirm it's silent.
-        with patch("locale.getpreferredencoding") as gpe:
-            gpe.return_value = "ASCII"
-            try:
-                _unicodefun._verify_python_env()
-            except RuntimeError as re:
-                self.fail(f"`patch_click()` failed, exception still raised: {re}")
-

     def test_root_logger_not_used_directly(self) -> None:
         def fail(*args: Any, **kwargs: Any) -> None:
             self.fail("Record created with root logger")
     def test_root_logger_not_used_directly(self) -> None:
         def fail(*args: Any, **kwargs: Any) -> None:
             self.fail("Record created with root logger")


@@ -1975,19 +1949,20 @@ class TestCaching:
         with cache_dir() as workspace:
             cache_file = get_cache_file(mode)
             cache_file.write_text("this is not a pickle", encoding="utf-8")
         with cache_dir() as workspace:
             cache_file = get_cache_file(mode)
             cache_file.write_text("this is not a pickle", encoding="utf-8")

-            assert black.read_cache(mode) == {}
+            assert black.Cache.read(mode).file_data == {}

             src = (workspace / "test.py").resolve()
             src.write_text("print('hello')", encoding="utf-8")
             invokeBlack([str(src)])
             src = (workspace / "test.py").resolve()
             src.write_text("print('hello')", encoding="utf-8")
             invokeBlack([str(src)])

-            cache = black.read_cache(mode)
-            assert str(src) in cache
+            cache = black.Cache.read(mode)
+            assert not cache.is_changed(src)

 
     def test_cache_single_file_already_cached(self) -> None:
         mode = DEFAULT_MODE
         with cache_dir() as workspace:
             src = (workspace / "test.py").resolve()
             src.write_text("print('hello')", encoding="utf-8")
 
     def test_cache_single_file_already_cached(self) -> None:
         mode = DEFAULT_MODE
         with cache_dir() as workspace:
             src = (workspace / "test.py").resolve()
             src.write_text("print('hello')", encoding="utf-8")

-            black.write_cache({}, [src], mode)
+            cache = black.Cache.read(mode)
+            cache.write([src])

             invokeBlack([str(src)])
             assert src.read_text(encoding="utf-8") == "print('hello')"
 
             invokeBlack([str(src)])
             assert src.read_text(encoding="utf-8") == "print('hello')"
 


@@ -2001,22 +1976,24 @@ class TestCaching:
             one.write_text("print('hello')", encoding="utf-8")
             two = (workspace / "two.py").resolve()
             two.write_text("print('hello')", encoding="utf-8")
             one.write_text("print('hello')", encoding="utf-8")
             two = (workspace / "two.py").resolve()
             two.write_text("print('hello')", encoding="utf-8")

-            black.write_cache({}, [one], mode)
+            cache = black.Cache.read(mode)
+            cache.write([one])

             invokeBlack([str(workspace)])
             assert one.read_text(encoding="utf-8") == "print('hello')"
             assert two.read_text(encoding="utf-8") == 'print("hello")\n'
             invokeBlack([str(workspace)])
             assert one.read_text(encoding="utf-8") == "print('hello')"
             assert two.read_text(encoding="utf-8") == 'print("hello")\n'

-            cache = black.read_cache(mode)
-            assert str(one) in cache
-            assert str(two) in cache
+            cache = black.Cache.read(mode)
+            assert not cache.is_changed(one)
+            assert not cache.is_changed(two)

 
 

+    @pytest.mark.incompatible_with_mypyc

     @pytest.mark.parametrize("color", [False, True], ids=["no-color", "with-color"])
     def test_no_cache_when_writeback_diff(self, color: bool) -> None:
         mode = DEFAULT_MODE
         with cache_dir() as workspace:
             src = (workspace / "test.py").resolve()
             src.write_text("print('hello')", encoding="utf-8")
     @pytest.mark.parametrize("color", [False, True], ids=["no-color", "with-color"])
     def test_no_cache_when_writeback_diff(self, color: bool) -> None:
         mode = DEFAULT_MODE
         with cache_dir() as workspace:
             src = (workspace / "test.py").resolve()
             src.write_text("print('hello')", encoding="utf-8")

-            with patch("black.read_cache") as read_cache, patch(
-                "black.write_cache"
+            with patch.object(black.Cache, "read") as read_cache, patch.object(
+                black.Cache, "write"

             ) as write_cache:
                 cmd = [str(src), "--diff"]
                 if color:
             ) as write_cache:
                 cmd = [str(src), "--diff"]
                 if color:


@@ -2024,8 +2001,8 @@ class TestCaching:
                 invokeBlack(cmd)
                 cache_file = get_cache_file(mode)
                 assert cache_file.exists() is False
                 invokeBlack(cmd)
                 cache_file = get_cache_file(mode)
                 assert cache_file.exists() is False

+                read_cache.assert_called_once()

                 write_cache.assert_not_called()
                 write_cache.assert_not_called()

-                read_cache.assert_not_called()

 
     @pytest.mark.parametrize("color", [False, True], ids=["no-color", "with-color"])
     @event_loop()
 
     @pytest.mark.parametrize("color", [False, True], ids=["no-color", "with-color"])
     @event_loop()


@@ -2058,18 +2035,19 @@ class TestCaching:
     def test_read_cache_no_cachefile(self) -> None:
         mode = DEFAULT_MODE
         with cache_dir():
     def test_read_cache_no_cachefile(self) -> None:
         mode = DEFAULT_MODE
         with cache_dir():

-            assert black.read_cache(mode) == {}
+            assert black.Cache.read(mode).file_data == {}

 
     def test_write_cache_read_cache(self) -> None:
         mode = DEFAULT_MODE
         with cache_dir() as workspace:
             src = (workspace / "test.py").resolve()
             src.touch()
 
     def test_write_cache_read_cache(self) -> None:
         mode = DEFAULT_MODE
         with cache_dir() as workspace:
             src = (workspace / "test.py").resolve()
             src.touch()

-            black.write_cache({}, [src], mode)
-            cache = black.read_cache(mode)
-            assert str(src) in cache
-            assert cache[str(src)] == black.get_cache_info(src)
+            write_cache = black.Cache.read(mode)
+            write_cache.write([src])
+            read_cache = black.Cache.read(mode)
+            assert not read_cache.is_changed(src)

 
 

+    @pytest.mark.incompatible_with_mypyc

     def test_filter_cached(self) -> None:
         with TemporaryDirectory() as workspace:
             path = Path(workspace)
     def test_filter_cached(self) -> None:
         with TemporaryDirectory() as workspace:
             path = Path(workspace)


@@ -2079,21 +2057,67 @@ class TestCaching:
             uncached.touch()
             cached.touch()
             cached_but_changed.touch()
             uncached.touch()
             cached.touch()
             cached_but_changed.touch()

-            cache = {
-                str(cached): black.get_cache_info(cached),
-                str(cached_but_changed): (0.0, 0),
-            }
-            todo, done = black.cache.filter_cached(
-                cache, {uncached, cached, cached_but_changed}
-            )
+            cache = black.Cache.read(DEFAULT_MODE)
+
+            orig_func = black.Cache.get_file_data
+
+            def wrapped_func(path: Path) -> FileData:
+                if path == cached:
+                    return orig_func(path)
+                if path == cached_but_changed:
+                    return FileData(0.0, 0, "")
+                raise AssertionError
+
+            with patch.object(black.Cache, "get_file_data", side_effect=wrapped_func):
+                cache.write([cached, cached_but_changed])
+            todo, done = cache.filtered_cached({uncached, cached, cached_but_changed})

             assert todo == {uncached, cached_but_changed}
             assert done == {cached}
 
             assert todo == {uncached, cached_but_changed}
             assert done == {cached}
 

+    def test_filter_cached_hash(self) -> None:
+        with TemporaryDirectory() as workspace:
+            path = Path(workspace)
+            src = (path / "test.py").resolve()
+            src.write_text("print('hello')", encoding="utf-8")
+            st = src.stat()
+            cache = black.Cache.read(DEFAULT_MODE)
+            cache.write([src])
+            cached_file_data = cache.file_data[str(src)]
+
+            todo, done = cache.filtered_cached([src])
+            assert todo == set()
+            assert done == {src}
+            assert cached_file_data.st_mtime == st.st_mtime
+
+            # Modify st_mtime
+            cached_file_data = cache.file_data[str(src)] = FileData(
+                cached_file_data.st_mtime - 1,
+                cached_file_data.st_size,
+                cached_file_data.hash,
+            )
+            todo, done = cache.filtered_cached([src])
+            assert todo == set()
+            assert done == {src}
+            assert cached_file_data.st_mtime < st.st_mtime
+            assert cached_file_data.st_size == st.st_size
+            assert cached_file_data.hash == black.Cache.hash_digest(src)
+
+            # Modify contents
+            src.write_text("print('hello world')", encoding="utf-8")
+            new_st = src.stat()
+            todo, done = cache.filtered_cached([src])
+            assert todo == {src}
+            assert done == set()
+            assert cached_file_data.st_mtime < new_st.st_mtime
+            assert cached_file_data.st_size != new_st.st_size
+            assert cached_file_data.hash != black.Cache.hash_digest(src)
+

     def test_write_cache_creates_directory_if_needed(self) -> None:
         mode = DEFAULT_MODE
         with cache_dir(exists=False) as workspace:
             assert not workspace.exists()
     def test_write_cache_creates_directory_if_needed(self) -> None:
         mode = DEFAULT_MODE
         with cache_dir(exists=False) as workspace:
             assert not workspace.exists()

-            black.write_cache({}, [], mode)
+            cache = black.Cache.read(mode)
+            cache.write([])

             assert workspace.exists()
 
     @event_loop()
             assert workspace.exists()
 
     @event_loop()


@@ -2107,15 +2131,17 @@ class TestCaching:
             clean = (workspace / "clean.py").resolve()
             clean.write_text('print("hello")\n', encoding="utf-8")
             invokeBlack([str(workspace)], exit_code=123)
             clean = (workspace / "clean.py").resolve()
             clean.write_text('print("hello")\n', encoding="utf-8")
             invokeBlack([str(workspace)], exit_code=123)

-            cache = black.read_cache(mode)
-            assert str(failing) not in cache
-            assert str(clean) in cache
+            cache = black.Cache.read(mode)
+            assert cache.is_changed(failing)
+            assert not cache.is_changed(clean)

 
     def test_write_cache_write_fail(self) -> None:
         mode = DEFAULT_MODE
 
     def test_write_cache_write_fail(self) -> None:
         mode = DEFAULT_MODE

-        with cache_dir(), patch.object(Path, "open") as mock:
-            mock.side_effect = OSError
-            black.write_cache({}, [], mode)
+        with cache_dir():
+            cache = black.Cache.read(mode)
+            with patch.object(Path, "open") as mock:
+                mock.side_effect = OSError
+                cache.write([])

 
     def test_read_cache_line_lengths(self) -> None:
         mode = DEFAULT_MODE
 
     def test_read_cache_line_lengths(self) -> None:
         mode = DEFAULT_MODE


@@ -2123,18 +2149,19 @@ class TestCaching:
         with cache_dir() as workspace:
             path = (workspace / "file.py").resolve()
             path.touch()
         with cache_dir() as workspace:
             path = (workspace / "file.py").resolve()
             path.touch()

-            black.write_cache({}, [path], mode)
-            one = black.read_cache(mode)
-            assert str(path) in one
-            two = black.read_cache(short_mode)
-            assert str(path) not in two
+            cache = black.Cache.read(mode)
+            cache.write([path])
+            one = black.Cache.read(mode)
+            assert not one.is_changed(path)
+            two = black.Cache.read(short_mode)
+            assert two.is_changed(path)

 
 
 def assert_collected_sources(
     src: Sequence[Union[str, Path]],
     expected: Sequence[Union[str, Path]],
     *,
 
 
 def assert_collected_sources(
     src: Sequence[Union[str, Path]],
     expected: Sequence[Union[str, Path]],
     *,

-    ctx: Optional[FakeContext] = None,
+    root: Optional[Path] = None,

     exclude: Optional[str] = None,
     include: Optional[str] = None,
     extend_exclude: Optional[str] = None,
     exclude: Optional[str] = None,
     include: Optional[str] = None,
     extend_exclude: Optional[str] = None,


@@ -2150,7 +2177,7 @@ def assert_collected_sources(
     )
     gs_force_exclude = None if force_exclude is None else compile_pattern(force_exclude)
     collected = black.get_sources(
     )
     gs_force_exclude = None if force_exclude is None else compile_pattern(force_exclude)
     collected = black.get_sources(

-        ctx=ctx or FakeContext(),
+        root=root or THIS_DIR,

         src=gs_src,
         quiet=False,
         verbose=False,
         src=gs_src,
         quiet=False,
         verbose=False,


@@ -2186,9 +2213,7 @@ class TestFileCollection:
             base / "b/.definitely_exclude/a.pyi",
         ]
         src = [base / "b/"]
             base / "b/.definitely_exclude/a.pyi",
         ]
         src = [base / "b/"]

-        ctx = FakeContext()
-        ctx.obj["root"] = base
-        assert_collected_sources(src, expected, ctx=ctx, extend_exclude=r"/exclude/")
+        assert_collected_sources(src, expected, root=base, extend_exclude=r"/exclude/")

 
     def test_gitignore_used_on_multiple_sources(self) -> None:
         root = Path(DATA_DIR / "gitignore_used_on_multiple_sources")
 
     def test_gitignore_used_on_multiple_sources(self) -> None:
         root = Path(DATA_DIR / "gitignore_used_on_multiple_sources")


@@ -2196,10 +2221,8 @@ class TestFileCollection:
             root / "dir1" / "b.py",
             root / "dir2" / "b.py",
         ]
             root / "dir1" / "b.py",
             root / "dir2" / "b.py",
         ]

-        ctx = FakeContext()
-        ctx.obj["root"] = root

         src = [root / "dir1", root / "dir2"]
         src = [root / "dir1", root / "dir2"]

-        assert_collected_sources(src, expected, ctx=ctx)
+        assert_collected_sources(src, expected, root=root)

 
     @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))
     def test_exclude_for_issue_1572(self) -> None:
 
     @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))
     def test_exclude_for_issue_1572(self) -> None:


@@ -2305,9 +2328,7 @@ class TestFileCollection:
         # If gitignore with */* is in root
         root = Path(DATA_DIR / "ignore_subfolders_gitignore_tests" / "subdir")
         expected = [root / "b.py"]
         # If gitignore with */* is in root
         root = Path(DATA_DIR / "ignore_subfolders_gitignore_tests" / "subdir")
         expected = [root / "b.py"]

-        ctx = FakeContext()
-        ctx.obj["root"] = root
-        assert_collected_sources([root], expected, ctx=ctx)
+        assert_collected_sources([root], expected, root=root)

 
         # If .gitignore with */* is nested
         root = Path(DATA_DIR / "ignore_subfolders_gitignore_tests")
 
         # If .gitignore with */* is nested
         root = Path(DATA_DIR / "ignore_subfolders_gitignore_tests")


@@ -2315,17 +2336,13 @@ class TestFileCollection:
             root / "a.py",
             root / "subdir" / "b.py",
         ]
             root / "a.py",
             root / "subdir" / "b.py",
         ]

-        ctx = FakeContext()
-        ctx.obj["root"] = root
-        assert_collected_sources([root], expected, ctx=ctx)
+        assert_collected_sources([root], expected, root=root)

 
         # If command is executed from outer dir
         root = Path(DATA_DIR / "ignore_subfolders_gitignore_tests")
         target = root / "subdir"
         expected = [target / "b.py"]
 
         # If command is executed from outer dir
         root = Path(DATA_DIR / "ignore_subfolders_gitignore_tests")
         target = root / "subdir"
         expected = [target / "b.py"]

-        ctx = FakeContext()
-        ctx.obj["root"] = root
-        assert_collected_sources([target], expected, ctx=ctx)
+        assert_collected_sources([target], expected, root=root)

 
     def test_empty_include(self) -> None:
         path = DATA_DIR / "include_exclude_tests"
 
     def test_empty_include(self) -> None:
         path = DATA_DIR / "include_exclude_tests"


@@ -2358,38 +2375,48 @@ class TestFileCollection:
         )
 
     @pytest.mark.incompatible_with_mypyc
         )
 
     @pytest.mark.incompatible_with_mypyc

-    def test_symlink_out_of_root_directory(self) -> None:
+    def test_symlinks(self) -> None:

         path = MagicMock()
         root = THIS_DIR.resolve()
         path = MagicMock()
         root = THIS_DIR.resolve()

-        child = MagicMock()

         include = re.compile(black.DEFAULT_INCLUDES)
         exclude = re.compile(black.DEFAULT_EXCLUDES)
         report = black.Report()
         gitignore = PathSpec.from_lines("gitwildmatch", [])
         include = re.compile(black.DEFAULT_INCLUDES)
         exclude = re.compile(black.DEFAULT_EXCLUDES)
         report = black.Report()
         gitignore = PathSpec.from_lines("gitwildmatch", [])

-        # `child` should behave like a symlink which resolved path is clearly
-        # outside of the `root` directory.
-        path.iterdir.return_value = [child]
-        child.resolve.return_value = Path("/a/b/c")
-        child.as_posix.return_value = "/a/b/c"
-        try:
-            list(
-                black.gen_python_files(
-                    path.iterdir(),
-                    root,
-                    include,
-                    exclude,
-                    None,
-                    None,
-                    report,
-                    {path: gitignore},
-                    verbose=False,
-                    quiet=False,
-                )
+
+        regular = MagicMock()
+        outside_root_symlink = MagicMock()
+        ignored_symlink = MagicMock()
+
+        path.iterdir.return_value = [regular, outside_root_symlink, ignored_symlink]
+
+        regular.absolute.return_value = root / "regular.py"
+        regular.resolve.return_value = root / "regular.py"
+        regular.is_dir.return_value = False
+
+        outside_root_symlink.absolute.return_value = root / "symlink.py"
+        outside_root_symlink.resolve.return_value = Path("/nowhere")
+
+        ignored_symlink.absolute.return_value = root / ".mypy_cache" / "symlink.py"
+
+        files = list(
+            black.gen_python_files(
+                path.iterdir(),
+                root,
+                include,
+                exclude,
+                None,
+                None,
+                report,
+                {path: gitignore},
+                verbose=False,
+                quiet=False,

             )
             )

-        except ValueError as ve:
-            pytest.fail(f"`get_python_files_in_dir()` failed: {ve}")
+        )
+        assert files == [regular]
+

         path.iterdir.assert_called_once()
         path.iterdir.assert_called_once()

-        child.resolve.assert_called_once()
+        outside_root_symlink.resolve.assert_called_once()
+        ignored_symlink.resolve.assert_not_called()

 
     @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))
     def test_get_sources_with_stdin(self) -> None:
 
     @patch("black.find_project_root", lambda *args: (THIS_DIR.resolve(), None))
     def test_get_sources_with_stdin(self) -> None:


@@ -2455,6 +2482,41 @@ class TestFileCollection:
         )
 
 
         )
 
 

+class TestDeFactoAPI:
+    """Test that certain symbols that are commonly used externally keep working.
+
+    We don't (yet) formally expose an API (see issue #779), but we should endeavor to
+    keep certain functions that external users commonly rely on working.
+
+    """
+
+    def test_format_str(self) -> None:
+        # format_str and Mode should keep working
+        assert (
+            black.format_str("print('hello')", mode=black.Mode()) == 'print("hello")\n'
+        )
+
+        # you can pass line length
+        assert (
+            black.format_str("print('hello')", mode=black.Mode(line_length=42))
+            == 'print("hello")\n'
+        )
+
+        # invalid input raises InvalidInput
+        with pytest.raises(black.InvalidInput):
+            black.format_str("syntax error", mode=black.Mode())
+
+    def test_format_file_contents(self) -> None:
+        # You probably should be using format_str() instead, but let's keep
+        # this one around since people do use it
+        assert (
+            black.format_file_contents("x=1", fast=True, mode=black.Mode()) == "x = 1\n"
+        )
+
+        with pytest.raises(black.NothingChanged):
+            black.format_file_contents("x = 1\n", fast=True, mode=black.Mode())
+
+

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