Add pytest test suite for commit-ai

commit-ai/README.md

@@ -33,4 +33,13 @@ Add to `~/.gitconfig`:
     aic = !python /path/to/commit.py --commit
 ```
 
+## Testing
+
+```bash
+pip install pytest anthropic
+pytest
+```
+
+Tests mock the Anthropic API, so no API key is needed. They cover diff parsing, message generation, edge cases, and auto-commit flow.
+
 **76 lines. Never write commits again.**

commit-ai/pytest.ini

@@ -0,0 +1,3 @@
+[pytest]
+pythonpath = .
+testpaths = .

commit-ai/test_commit.py

@@ -0,0 +1,133 @@
+import pytest
+from unittest.mock import patch, MagicMock
+from commit import CommitAI
+
+
+@pytest.fixture
+def ai():
+    with patch.dict("os.environ", {"ANTHROPIC_API_KEY": "test-key"}):
+        return CommitAI()
+
+
+class TestGetDiff:
+    def test_returns_stripped_stdout(self, ai):
+        with patch("commit.subprocess.run") as mock_run:
+            mock_run.return_value.stdout = "  diff content\n  "
+            result = ai.get_diff(staged_only=True)
+            assert result == "diff content"
+            mock_run.assert_called_once_with(
+                ["git", "diff", "--cached"], capture_output=True, text=True
+            )
+
+    def test_uses_staged_diff_by_default(self, ai):
+        with patch("commit.subprocess.run") as mock_run:
+            mock_run.return_value.stdout = ""
+            ai.get_diff()
+            mock_run.assert_called_once_with(
+                ["git", "diff", "--cached"], capture_output=True, text=True
+            )
+
+    def test_includes_unstaged_when_requested(self, ai):
+        with patch("commit.subprocess.run") as mock_run:
+            mock_run.return_value.stdout = ""
+            ai.get_diff(staged_only=False)
+            mock_run.assert_called_once_with(
+                ["git", "diff", "HEAD"], capture_output=True, text=True
+            )
+
+    def test_returns_empty_string_on_no_changes(self, ai):
+        with patch("commit.subprocess.run") as mock_run:
+            mock_run.return_value.stdout = "  "
+            assert ai.get_diff() == ""
+
+
+class TestGetBranch:
+    def test_returns_current_branch(self, ai):
+        with patch("commit.subprocess.run") as mock_run:
+            mock_run.return_value.stdout = "feature-branch\n"
+            assert ai.get_branch() == "feature-branch"
+
+    def test_strips_whitespace(self, ai):
+        with patch("commit.subprocess.run") as mock_run:
+            mock_run.return_value.stdout = "  main  \n"
+            assert ai.get_branch() == "  main  "
+
+
+class TestGetRecentCommits:
+    def test_returns_recent_commits(self, ai):
+        with patch("commit.subprocess.run") as mock_run:
+            mock_run.return_value.stdout = "feat: add login\nfix: fix crash\ndocs: update readme"
+            result = ai.get_recent_commits(3)
+            assert "feat: add login" in result
+            mock_run.assert_called_once_with(
+                ["git", "log", "-3", "--pretty=format:%s"], capture_output=True, text=True
+            )
+
+
+class TestGenerateCommitMessage:
+    def test_mocks_anthropic_call(self, ai):
+        with patch.object(ai.client.messages, "create") as mock_create:
+            mock_create.return_value.content = [
+                MagicMock(text="feat(api): add user authentication")
+            ]
+            result = ai.generate_commit_message(
+                diff="+def login(): pass",
+                conventional=True,
+                branch="feature/login",
+                recent_style="feat: stuff",
+            )
+            assert result == "feat(api): add user authentication"
+            assert mock_create.called
+
+    def test_truncates_large_diff_to_4000_chars(self, ai):
+        with patch.object(ai.client.messages, "create") as mock_create:
+            mock_create.return_value.content = [MagicMock(text="fix: big change")]
+            large_diff = "a" * 5000
+            ai.generate_commit_message(diff=large_diff, conventional=True)
+            prompt = mock_create.call_args[1]["messages"][0]["content"]
+            assert prompt.count("a") == 4000
+
+    def test_adds_conventional_commit_requirement(self, ai):
+        with patch.object(ai.client.messages, "create") as mock_create:
+            mock_create.return_value.content = [MagicMock(text="fix: stuff")]
+            ai.generate_commit_message(diff="+x", conventional=True)
+            prompt = mock_create.call_args[1]["messages"][0]["content"]
+            assert "Conventional Commits" in prompt
+
+    def test_omits_conventional_when_not_requested(self, ai):
+        with patch.object(ai.client.messages, "create") as mock_create:
+            mock_create.return_value.content = [MagicMock(text="some change")]
+            ai.generate_commit_message(diff="+x", conventional=False)
+            prompt = mock_create.call_args[1]["messages"][0]["content"]
+            assert "Conventional Commits" not in prompt
+
+
+class TestGenerate:
+    def test_returns_error_on_empty_diff(self, ai):
+        with patch.object(ai, "get_diff", return_value=""):
+            result = ai.generate()
+            assert "No changes" in result
+
+    def test_generates_message_with_diff(self, ai):
+        with (
+            patch.object(ai, "get_diff", return_value="+new code"),
+            patch.object(ai, "get_branch", return_value="main"),
+            patch.object(ai, "get_recent_commits", return_value="fix: prior"),
+            patch.object(ai, "generate_commit_message", return_value="feat: add feature"),
+        ):
+            result = ai.generate()
+            assert result == "feat: add feature"
+
+    def test_auto_commit_runs_git_commit(self, ai):
+        with (
+            patch.object(ai, "get_diff", return_value="+new code"),
+            patch.object(ai, "get_branch", return_value="main"),
+            patch.object(ai, "get_recent_commits", return_value="fix: prior"),
+            patch.object(ai, "generate_commit_message", return_value="feat: add feature"),
+            patch("commit.subprocess.run") as mock_run,
+        ):
+            result = ai.generate(auto_commit=True)
+            assert "Committed" in result
+            mock_run.assert_called_once_with(
+                ["git", "commit", "-m", "feat: add feature"], check=True
+            )