Use a more intelligent default language version

tests/languages/all_test.py

@@ -12,9 +12,7 @@ from pre_commit.languages.all import languages
 def test_install_environment_argspec(language):
     expected_argspec = inspect.ArgSpec(
         args=['repo_cmd_runner', 'version', 'additional_dependencies'],
-        varargs=None,
-        keywords=None,
-        defaults=('default', ()),
+        varargs=None, keywords=None, defaults=None,
     )
     argspec = inspect.getargspec(languages[language].install_environment)
     assert argspec == expected_argspec
@@ -33,3 +31,12 @@ def test_run_hook_argpsec(language):
     )
     argspec = inspect.getargspec(languages[language].run_hook)
     assert argspec == expected_argspec
+
+
+@pytest.mark.parametrize('language', all_languages)
+def test_get_default_version_argspec(language):
+    expected_argspec = inspect.ArgSpec(
+        args=[], varargs=None, keywords=None, defaults=None,
+    )
+    argspec = inspect.getargspec(languages[language].get_default_version)
+    assert argspec == expected_argspec

tests/manifest_test.py

@@ -11,8 +11,7 @@ from testing.util import get_head_sha
 @pytest.yield_fixture
 def manifest(store, tempdir_factory):
     path = make_repo(tempdir_factory, 'script_hooks_repo')
-    head_sha = get_head_sha(path)
-    repo_path = store.clone(path, head_sha)
+    repo_path = store.clone(path, get_head_sha(path))
     yield Manifest(repo_path, path)
 
 
@@ -76,3 +75,13 @@ def test_legacy_manifest_warn(store, tempdir_factory, log_warning_mock):
         'If `pre-commit autoupdate` does not silence this warning consider '
         'making an issue / pull request.'.format(path)
     )
+
+
+def test_default_python_language_version(store, tempdir_factory):
+    path = make_repo(tempdir_factory, 'python_hooks_repo')
+    repo_path = store.clone(path, get_head_sha(path))
+    manifest = Manifest(repo_path, path)
+
+    # This assertion is difficult as it is version dependent, just assert
+    # that it is *something*
+    assert manifest.hooks['foo']['language_version'] != 'default'

tests/repository_test.py

@@ -442,7 +442,7 @@ def test_venvs(tempdir_factory, store):
     config = make_config_from_repo(path)
     repo = Repository.create(config, store)
     venv, = repo._venvs
-    assert venv == (mock.ANY, 'python', 'default', [])
+    assert venv == (mock.ANY, 'python', python.get_default_version(), [])
 
 
 @pytest.mark.integration
@@ -452,7 +452,7 @@ def test_additional_dependencies(tempdir_factory, store):
     config['hooks'][0]['additional_dependencies'] = ['pep8']
     repo = Repository.create(config, store)
     venv, = repo._venvs
-    assert venv == (mock.ANY, 'python', 'default', ['pep8'])
+    assert venv == (mock.ANY, 'python', python.get_default_version(), ['pep8'])
 
 
 @pytest.mark.integration
@@ -591,7 +591,8 @@ def test_control_c_control_c_on_install(tempdir_factory, store):
                 repo.run_hook(hook, [])
 
     # Should have made an environment, however this environment is broken!
-    assert os.path.exists(repo._cmd_runner.path('py_env-default'))
+    envdir = 'py_env-{}'.format(python.get_default_version())
+    assert repo._cmd_runner.exists(envdir)
 
     # However, it should be perfectly runnable (reinstall after botched
     # install)