Add more cases to symlink inclusion test

Author: sth

tests/test_black.py

@@ -2422,27 +2422,51 @@ def test_extend_exclude(self) -> None:
 
     @pytest.mark.incompatible_with_mypyc
     def test_symlinks(self) -> None:
-        path = MagicMock()
         root = THIS_DIR.resolve()
         include = re.compile(black.DEFAULT_INCLUDES)
         exclude = re.compile(black.DEFAULT_EXCLUDES)
         report = black.Report()
         gitignore = PathSpec.from_lines("gitwildmatch", [])
 
         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
+        regular.is_file.return_value = True
 
+        outside_root_symlink = MagicMock()
         outside_root_symlink.absolute.return_value = root / "symlink.py"
         outside_root_symlink.resolve.return_value = Path("/nowhere")
+        outside_root_symlink.is_dir.return_value = False
+        outside_root_symlink.is_file.return_value = True
 
+        ignored_symlink = MagicMock()
         ignored_symlink.absolute.return_value = root / ".mypy_cache" / "symlink.py"
+        ignored_symlink.is_dir.return_value = False
+        ignored_symlink.is_file.return_value = True
+
+        # A symlink that has an excluded name, but points to an included name
+        symlink_excluded_name = MagicMock()
+        symlink_excluded_name.absolute.return_value = root / "excluded_name"
+        symlink_excluded_name.resolve.return_value = root / "included_name.py"
+        symlink_excluded_name.is_dir.return_value = False
+        symlink_excluded_name.is_file.return_value = True
+
+        # A symlink that has an included name, but points to an excluded name
+        symlink_included_name = MagicMock()
+        symlink_included_name.absolute.return_value = root / "included_name.py"
+        symlink_included_name.resolve.return_value = root / "excluded_name"
+        symlink_included_name.is_dir.return_value = False
+        symlink_included_name.is_file.return_value = True
+
+        path = MagicMock()
+        path.iterdir.return_value = [
+            regular,
+            outside_root_symlink,
+            ignored_symlink,
+            symlink_excluded_name,
+            symlink_included_name,
+        ]
 
         files = list(
             black.gen_python_files(
@@ -2458,7 +2482,7 @@ def test_symlinks(self) -> None:
                 quiet=False,
             )
         )
-        assert files == [regular]
+        assert files == [regular, symlink_included_name]
 
         path.iterdir.assert_called_once()
         outside_root_symlink.resolve.assert_called_once()