Soft comparison of --required-version (#2832)

Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>
Co-authored-by: Felix Hildén <felix.hilden@gmail.com>

CHANGES.md

@@ -5,6 +5,7 @@
 ### Configuration
 
 - Do not format `__pypackages__` directories by default (#2836)
+- Add support for specifying stable version with `--required-version` (#2832).
 
 ## 22.1.0
 

src/black/__init__.py

@@ -291,7 +291,8 @@ def validate_regex(
     type=str,
     help=(
         "Require a specific version of Black to be running (useful for unifying results"
-        " across many environments e.g. with a pyproject.toml file)."
+        " across many environments e.g. with a pyproject.toml file). It can be"
+        " either a major version number or an exact version."
     ),
 )
 @click.option(
@@ -474,7 +475,11 @@ def main(
                 out(f"Using configuration in '{config}'.", fg="blue")
 
     error_msg = "Oh no! 💥 💔 💥"
-    if required_version and required_version != __version__:
+    if (
+        required_version
+        and required_version != __version__
+        and required_version != __version__.split(".")[0]
+    ):
         err(
             f"{error_msg} The required version `{required_version}` does not match"
             f" the running version `{__version__}`!"

tests/test_black.py

@@ -1198,6 +1198,20 @@ def test_required_version_matches_version(self) -> None:
             ignore_config=True,
         )
 
+    def test_required_version_matches_partial_version(self) -> None:
+        self.invokeBlack(
+            ["--required-version", black.__version__.split(".")[0], "-c", "0"],
+            exit_code=0,
+            ignore_config=True,
+        )
+
+    def test_required_version_does_not_match_on_minor_version(self) -> None:
+        self.invokeBlack(
+            ["--required-version", black.__version__.split(".")[0] + ".999", "-c", "0"],
+            exit_code=1,
+            ignore_config=True,
+        )
+
     def test_required_version_does_not_match_version(self) -> None:
         result = BlackRunner().invoke(
             black.main,