deprecate python_venv language

tests/repository_test.py

@@ -129,11 +129,21 @@ def test_python_hook_weird_setup_cfg(in_git_dir, tempdir_factory, store):
     )
 
 
-def test_python_venv(tempdir_factory, store):
-    _test_hook_repo(
-        tempdir_factory, store, 'python_venv_hooks_repo',
-        'foo', [os.devnull],
-        f'[{os.devnull!r}]\nHello World\n'.encode(),
+def test_python_venv_deprecation(store, caplog):
+    config = {
+        'repo': 'local',
+        'hooks': [{
+            'id': 'example',
+            'name': 'example',
+            'language': 'python_venv',
+            'entry': 'echo hi',
+        }],
+    }
+    _get_hook(config, store, 'example')
+    assert caplog.messages[-1] == (
+        '`repo: local` uses deprecated `language: python_venv`.  '
+        'This is an alias for `language: python`.  '
+        'Often `pre-commit autoupdate --repo local` will fix this.'
     )