name: testing
description: Load when editing test_*, .test., or *_test.py files, or working with pytest/jest frameworks. Provides testing patterns for Python and TypeScript projects.
Testing
Merged Skills
- pytest: Python testing with async support
- jest: TypeScript/React component testing
- e2e: End-to-end integration testing
⚠️ Critical Gotchas
| Category |
Pattern |
Solution |
| Async fixtures |
Fixture not async |
Use @pytest.fixture with async def |
| Over-mocking |
Everything mocked |
Only mock at service boundaries |
| Flaky tests |
Random failures |
Add pytest.mark.flaky or fix race condition |
| E2E timing |
Tests fail intermittently |
Use explicit waits, not sleep() |
| Shared state |
Tests affect each other |
Fresh setup each test, isolate state |
| Wrong level |
Unit test for integration |
Match test type to what you're testing |
Rules
| Rule |
Pattern |
| Test behavior |
Test what it does, not how |
| Isolate tests |
No shared state between tests |
| Fast first |
Run API/UI tests before E2E |
| Meaningful names |
Describe expected behavior in test name |
| E2E confirms |
Only run E2E after API+UI pass |
| Mock boundaries |
Mock external services, not internal logic |
Avoid
| ❌ Bad |
✅ Good |
| Testing implementation |
Testing behavior |
| Shared state |
Fresh setup each test |
| Mock everything |
Mock boundaries only |
| E2E for unit logic |
E2E for user flows |
time.sleep() in E2E |
Explicit waits |
| Generic test names |
test_create_script_returns_201 |
Testing Hierarchy
| Level |
Target |
When |
Command |
| 1. API |
Backend endpoints |
After API changes |
pytest backend/tests/api/ |
| 2. UI |
Components, pages |
After frontend changes |
npm test |
| 3. E2E |
Full flow |
Final confirmation |
pytest backend/tests/e2e/ -m e2e |
Patterns
# Pattern 1: API test with async client
class TestScriptAPI:
async def test_create_script_returns_201(self, client):
response = await client.post("/api/scripts/", json={"name": "test"})
assert response.status_code == 201
assert response.json()["id"] is not None
async def test_list_scripts_returns_all(self, client, sample_scripts):
response = await client.get("/api/scripts/")
assert len(response.json()) == len(sample_scripts)
# Pattern 2: Async fixture
@pytest.fixture
async def sample_scripts(db_session):
scripts = [Script(name=f"script_{i}") for i in range(3)]
db_session.add_all(scripts)
await db_session.commit()
return scripts
// Pattern 3: React component test
it('renders script list correctly', () => {
render(<ScriptList scripts={mockScripts} />);
expect(screen.getAllByTestId('script-item')).toHaveLength(3);
});
it('calls onRun when run button clicked', () => {
const onRun = jest.fn();
render(<ScriptCard script={mockScript} onRun={onRun} />);
fireEvent.click(screen.getByRole('button', { name: /run/i }));
expect(onRun).toHaveBeenCalledWith(mockScript.id);
});
# Pattern 4: E2E test with full flow
@pytest.mark.e2e
class TestScriptWorkflow:
"""Final confirmation: full user flow"""
async def test_create_run_delete_script(self, e2e_client):
# Create
create_resp = await e2e_client.post("/api/scripts/", json={"name": "E2E Test"})
script_id = create_resp.json()["id"]
# Run
run_resp = await e2e_client.post(f"/api/scripts/{script_id}/run")
assert run_resp.json()["status"] == "completed"
# Delete
delete_resp = await e2e_client.delete(f"/api/scripts/{script_id}")
assert delete_resp.status_code == 204
Commands
| Task |
Command |
| API tests |
cd backend && pytest tests/api/ -v |
| UI tests |
cd frontend && npm test |
| E2E tests |
cd backend && pytest tests/e2e/ -v -m e2e |
| All tests |
pytest && npm test && pytest -m e2e |
| Single file |
pytest tests/test_specific.py -v |
| With coverage |
pytest --cov=app tests/ |
By