Make Go a first class language

tests/languages/golang_test.py

@@ -0,0 +1,43 @@
+from __future__ import annotations
+
+import re
+from unittest import mock
+
+import pytest
+
+import pre_commit.constants as C
+from pre_commit.languages import golang
+from pre_commit.languages import helpers
+
+
+ACTUAL_GET_DEFAULT_VERSION = golang.get_default_version.__wrapped__
+
+
+@pytest.fixture
+def exe_exists_mck():
+    with mock.patch.object(helpers, 'exe_exists') as mck:
+        yield mck
+
+
+def test_golang_default_version_system_available(exe_exists_mck):
+    exe_exists_mck.return_value = True
+    assert ACTUAL_GET_DEFAULT_VERSION() == 'system'
+
+
+def test_golang_default_version_system_not_available(exe_exists_mck):
+    exe_exists_mck.return_value = False
+    assert ACTUAL_GET_DEFAULT_VERSION() == C.DEFAULT
+
+
+ACTUAL_INFER_GO_VERSION = golang._infer_go_version.__wrapped__
+
+
+def test_golang_infer_go_version_not_default():
+    assert ACTUAL_INFER_GO_VERSION('1.19.4') == '1.19.4'
+
+
+def test_golang_infer_go_version_default():
+    version = ACTUAL_INFER_GO_VERSION(C.DEFAULT)
+
+    assert version != C.DEFAULT
+    assert re.match(r'^\d+\.\d+\.\d+$', version)