madduck's git repository

Every one of the projects in this repository is available at the canonical URL git://git.madduck.net/madduck/pub/<projectpath> — see each project's metadata for the exact URL.

All patches and comments are welcome. Please squash your changes to logical commits before using git-format-patch and git-send-email to patches@git.madduck.net. If you'd read over the Git project's submission guidelines and adhered to them, I'd be especially grateful.

SSH access, as well as push access can be individually arranged.

If you use my repositories frequently, consider adding the following snippet to ~/.gitconfig and using the third clone URL listed for each project:

[url "git://git.madduck.net/madduck/"]
  insteadOf = madduck:

Push contributors to use Next PR Number (#2080)
[etc/vim.git] / tests / test_black.py
index a688c8780efe682530d11ccf55c9995eea8608a8..c603233efc40b58e874e5c76461ee74f6f491ded 100644 (file)
@@ -263,6 +263,15 @@ 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)
+
     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 +296,7 @@ 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 +304,14 @@ 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 +323,12 @@ 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)
@@ -395,6 +407,31 @@ class BlackTestCase(BlackBaseTestCase):
         black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, mode)
 
         black.assert_equivalent(source, actual)
         black.assert_stable(source, actual, mode)
 
+    def test_skip_magic_trailing_comma(self) -> None:
+        source, _ = read_data("expression.py")
+        expected, _ = read_data("expression_skip_magic_trailing_comma.diff")
+        tmp_file = Path(black.dump_to_file(source))
+        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, ["-C", "--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)
+        actual = actual.rstrip() + "\n"  # the diff output has a trailing space
+        if expected != actual:
+            dump = black.dump_to_file(actual)
+            msg = (
+                "Expected diff isn't equal to the actual. If you made changes to"
+                " expression.py and this is an anticipated difference, overwrite"
+                f" tests/data/expression_skip_magic_trailing_comma.diff with {dump}"
+            )
+            self.assertEqual(expected, actual, msg)
+
     @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")
@@ -978,7 +1015,7 @@ class BlackTestCase(BlackBaseTestCase):
                 fobj.write("print('hello')")
             self.invokeBlack([str(src)])
             cache = black.read_cache(mode)
                 fobj.write("print('hello')")
             self.invokeBlack([str(src)])
             cache = black.read_cache(mode)
-            self.assertIn(src, cache)
+            self.assertIn(str(src), cache)
 
     def test_cache_single_file_already_cached(self) -> None:
         mode = DEFAULT_MODE
 
     def test_cache_single_file_already_cached(self) -> None:
         mode = DEFAULT_MODE
@@ -1010,8 +1047,8 @@ class BlackTestCase(BlackBaseTestCase):
             with two.open("r") as fobj:
                 self.assertEqual(fobj.read(), 'print("hello")\n')
             cache = black.read_cache(mode)
             with two.open("r") as fobj:
                 self.assertEqual(fobj.read(), 'print("hello")\n')
             cache = black.read_cache(mode)
-            self.assertIn(one, cache)
-            self.assertIn(two, cache)
+            self.assertIn(str(one), cache)
+            self.assertIn(str(two), cache)
 
     def test_no_cache_when_writeback_diff(self) -> None:
         mode = DEFAULT_MODE
 
     def test_no_cache_when_writeback_diff(self) -> None:
         mode = DEFAULT_MODE
@@ -1091,8 +1128,8 @@ class BlackTestCase(BlackBaseTestCase):
             src.touch()
             black.write_cache({}, [src], mode)
             cache = black.read_cache(mode)
             src.touch()
             black.write_cache({}, [src], mode)
             cache = black.read_cache(mode)
-            self.assertIn(src, cache)
-            self.assertEqual(cache[src], black.get_cache_info(src))
+            self.assertIn(str(src), cache)
+            self.assertEqual(cache[str(src)], black.get_cache_info(src))
 
     def test_filter_cached(self) -> None:
         with TemporaryDirectory() as workspace:
 
     def test_filter_cached(self) -> None:
         with TemporaryDirectory() as workspace:
@@ -1103,7 +1140,10 @@ class BlackTestCase(BlackBaseTestCase):
             uncached.touch()
             cached.touch()
             cached_but_changed.touch()
             uncached.touch()
             cached.touch()
             cached_but_changed.touch()
-            cache = {cached: black.get_cache_info(cached), cached_but_changed: (0.0, 0)}
+            cache = {
+                str(cached): black.get_cache_info(cached),
+                str(cached_but_changed): (0.0, 0),
+            }
             todo, done = black.filter_cached(
                 cache, {uncached, cached, cached_but_changed}
             )
             todo, done = black.filter_cached(
                 cache, {uncached, cached, cached_but_changed}
             )
@@ -1131,8 +1171,8 @@ class BlackTestCase(BlackBaseTestCase):
                 fobj.write('print("hello")\n')
             self.invokeBlack([str(workspace)], exit_code=123)
             cache = black.read_cache(mode)
                 fobj.write('print("hello")\n')
             self.invokeBlack([str(workspace)], exit_code=123)
             cache = black.read_cache(mode)
-            self.assertNotIn(failing, cache)
-            self.assertIn(clean, cache)
+            self.assertNotIn(str(failing), cache)
+            self.assertIn(str(clean), cache)
 
     def test_write_cache_write_fail(self) -> None:
         mode = DEFAULT_MODE
 
     def test_write_cache_write_fail(self) -> None:
         mode = DEFAULT_MODE
@@ -1185,9 +1225,9 @@ class BlackTestCase(BlackBaseTestCase):
             path.touch()
             black.write_cache({}, [path], mode)
             one = black.read_cache(mode)
             path.touch()
             black.write_cache({}, [path], mode)
             one = black.read_cache(mode)
-            self.assertIn(path, one)
+            self.assertIn(str(path), one)
             two = black.read_cache(short_mode)
             two = black.read_cache(short_mode)
-            self.assertNotIn(path, two)
+            self.assertNotIn(str(path), two)
 
     def test_single_file_force_pyi(self) -> None:
         pyi_mode = replace(DEFAULT_MODE, is_pyi=True)
 
     def test_single_file_force_pyi(self) -> None:
         pyi_mode = replace(DEFAULT_MODE, is_pyi=True)
@@ -1201,9 +1241,9 @@ class BlackTestCase(BlackBaseTestCase):
                 actual = fh.read()
             # verify cache with --pyi is separate
             pyi_cache = black.read_cache(pyi_mode)
                 actual = fh.read()
             # verify cache with --pyi is separate
             pyi_cache = black.read_cache(pyi_mode)
-            self.assertIn(path, pyi_cache)
+            self.assertIn(str(path), pyi_cache)
             normal_cache = black.read_cache(DEFAULT_MODE)
             normal_cache = black.read_cache(DEFAULT_MODE)
-            self.assertNotIn(path, normal_cache)
+            self.assertNotIn(str(path), normal_cache)
         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)
@@ -1230,8 +1270,8 @@ class BlackTestCase(BlackBaseTestCase):
             pyi_cache = black.read_cache(pyi_mode)
             normal_cache = black.read_cache(reg_mode)
             for path in paths:
             pyi_cache = black.read_cache(pyi_mode)
             normal_cache = black.read_cache(reg_mode)
             for path in paths:
-                self.assertIn(path, pyi_cache)
-                self.assertNotIn(path, normal_cache)
+                self.assertIn(str(path), pyi_cache)
+                self.assertNotIn(str(path), normal_cache)
 
     def test_pipe_force_pyi(self) -> None:
         source, expected = read_data("force_pyi")
 
     def test_pipe_force_pyi(self) -> None:
         source, expected = read_data("force_pyi")
@@ -1255,9 +1295,9 @@ class BlackTestCase(BlackBaseTestCase):
                 actual = fh.read()
             # verify cache with --target-version is separate
             py36_cache = black.read_cache(py36_mode)
                 actual = fh.read()
             # verify cache with --target-version is separate
             py36_cache = black.read_cache(py36_mode)
-            self.assertIn(path, py36_cache)
+            self.assertIn(str(path), py36_cache)
             normal_cache = black.read_cache(reg_mode)
             normal_cache = black.read_cache(reg_mode)
-            self.assertNotIn(path, normal_cache)
+            self.assertNotIn(str(path), normal_cache)
         self.assertEqual(actual, expected)
 
     @event_loop()
         self.assertEqual(actual, expected)
 
     @event_loop()
@@ -1282,8 +1322,8 @@ class BlackTestCase(BlackBaseTestCase):
             pyi_cache = black.read_cache(py36_mode)
             normal_cache = black.read_cache(reg_mode)
             for path in paths:
             pyi_cache = black.read_cache(py36_mode)
             normal_cache = black.read_cache(reg_mode)
             for path in paths:
-                self.assertIn(path, pyi_cache)
-                self.assertNotIn(path, normal_cache)
+                self.assertIn(str(path), pyi_cache)
+                self.assertNotIn(str(path), normal_cache)
 
     def test_pipe_force_py36(self) -> None:
         source, expected = read_data("force_py36")
 
     def test_pipe_force_py36(self) -> None:
         source, expected = read_data("force_py36")
@@ -1310,7 +1350,14 @@ 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))
@@ -1332,8 +1379,9 @@ 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,
@@ -1354,8 +1402,9 @@ 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,
@@ -1377,8 +1426,9 @@ 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,
@@ -1404,8 +1454,37 @@ 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,
@@ -1429,9 +1508,10 @@ 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,
             )
@@ -1515,7 +1595,14 @@ 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))
@@ -1545,25 +1632,21 @@ 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(
@@ -1571,7 +1654,8 @@ 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,
@@ -1579,8 +1663,8 @@ 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:
@@ -1629,7 +1713,14 @@ 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:
@@ -1643,7 +1734,14 @@ 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()
@@ -1748,6 +1846,34 @@ 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
@@ -1765,6 +1891,33 @@ class BlackTestCase(BlackBaseTestCase):
         finally:
             os.chdir(str(old_cwd))
 
         finally:
             os.chdir(str(old_cwd))
 
+    def test_newline_comment_interaction(self) -> None:
+        source = "class A:\\\r\n# type: ignore\n pass\n"
+        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)
+
 
 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()