designing-tests

# Designing Tests

## Test Implementation Workflow

Copy this checklist and track progress:

```
Test Implementation Progress:
- [ ] Step 1: Identify what to test
- [ ] Step 2: Select appropriate test type
- [ ] Step 3: Write tests following templates
- [ ] Step 4: Run tests and verify passing
- [ ] Step 5: Check coverage meets targets
- [ ] Step 6: Fix any failing tests
```

## Testing Pyramid

Apply the testing pyramid for balanced coverage:

```
        /\
       /  \     E2E Tests (10%)
      /----\    - Critical user journeys
     /      \   - Slow but comprehensive
    /--------\  Integration Tests (20%)
   /          \ - Component interactions
  /------------\ - API contracts
 /              \ Unit Tests (70%)
/________________\ - Fast, isolated
                   - Business logic focus
```

## Framework Selection

### JavaScript/TypeScript
| Type | Recommended | Alternative |
|------|-------------|-------------|
| Unit | Vitest | Jest |
| Integration | Vitest + MSW | Jest + SuperTest |
| E2E | Playwright | Cypress |
| Component | Testing Library | Enzyme |

### Python
| Type | Recommended | Alternative |
|------|-------------|-------------|
| Unit | pytest | unittest |
| Integration | pytest + httpx | pytest + requests |
| E2E | Playwright | Selenium |
| API | pytest + FastAPI TestClient | - |

### Go
| Type | Recommended |
|------|-------------|
| Unit | testing + testify |
| Integration | testing + httptest |
| E2E | testing + chromedp |

## Test Structure Templates

### Unit Test
```javascript
describe('[Unit] ComponentName', () => {
  describe('methodName', () => {
    it('should [expected behavior] when [condition]', () => {
      // Arrange
      const input = createTestInput();

      // Act
      const result = methodName(input);

      // Assert
      expect(result).toEqual(expectedOutput);
    });

    it('should throw error when [invalid condition]', () => {
      expect(() => methodName(invalidInput)).toThrow(ExpectedError);
    });
  });
});
```