# Tdd Workflow

> Use this skill when writing new features, fixing bugs, or refactoring code. Enforces test-driven development with 80%+ coverage including unit, integration, and E2E tests.

- Skill: `majiayu000/tdd-workflow-9` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add majiayu000/tdd-workflow-9`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/tdd-workflow-9/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/tdd-workflow-9

---


# Test-Driven Development Workflow

This skill ensures all code development follows TDD principles with comprehensive test coverage.

## When to Activate

- Writing new features or functionality
- Fixing bugs or issues
- Refactoring existing code
- Adding API endpoints
- Creating new components

## Core Principles

### 1. Tests BEFORE Code

ALWAYS write tests first, then implement code to make tests pass.

### 2. Coverage Requirements

- Minimum 80% coverage (unit + integration + E2E)
- All edge cases covered
- Error scenarios tested
- Boundary conditions verified

### 3. Test Types

#### Unit Tests

- Individual functions and utilities
- Component logic
- Pure functions
- Helpers and utilities

#### Integration Tests

- API endpoints
- Database operations
- Service interactions
- External API calls

#### E2E Tests (Playwright)

- Critical user flows
- Complete workflows
- Browser automation
- UI interactions

## TDD Workflow Steps

### Step 1: Write User Journeys

```
As a [role], I want to [action], so that [benefit]

Example:
As a user, I want to search for markets semantically,
so that I can find relevant markets even without exact keywords.
```

### Step 2: Generate Test Cases

For each user journey, create comprehensive test cases:

```typescript
describe('Semantic Search', () => {
  it('returns relevant markets for query', async () => {
    // Test implementation
  });

  it('handles empty query gracefully', async () => {
    // Test edge case
  });

  it('falls back to substring search when Redis unavailable', async () => {
    // Test fallback behavior
  });

  it('sorts results by similarity score', async () => {
    // Test sorting logic
  });
});
```

### Step 3: Run Tests (They Should Fail)

```bash
npm test
# Tests should fail - we haven't implemented yet
```

### Step 4: Implement Code

Write minimal code to make tests pass:

```typescript
// Implementation guided by tests
export async function searchMarkets(query: string) {
  // Implementation here
}
```

### Step 5: Run Tests Again

```bash
npm test
# Tests should now pass
```

### Step 6: Refactor

Improve code quality while keeping tests green:

- Remove duplication
- Improve naming
- Optimize performance
- Enhance readability

### Step 7: Verify Coverage

```bash
npm run test:coverage
# Verify 80%+ coverage achieved
```

## Testing Patterns

### Unit Test Pattern (Jest/Vitest)

```typescript
import { render, screen, fireEvent } from '@testing-library/react'
import { Button } from './Button'

describe('Button Component', () => {
  it('renders with correct text', () => {
    render(<Button>Click me</Button>)
    expect(screen.getByText('Click me')).toBeInTheDocument()
  })

  it('calls onClick when clicked', () => {
    const handleClick = jest.fn()
    render(<Button onClick={handleClick}>Click</Button>)

    fireEvent.click(screen.getByRole('button'))

    expect(handleClick).toHaveBeenCalledTimes(1)
  })

  it('is disabled when disabled prop is true', () => {
    render(<Button disabled>Click</Button>)
    expect(screen.getByRole('button')).toBeDisabled()
  })
})
```

### API Integration Test Pattern

```typescript
import { NextRequest } from 'next/server';
import { GET } from './route';

describe('GET /api/markets', () => {
  it('returns markets successfully', async () => {
    const request = new NextRequest('http://localhost/api/markets');
    const response = await GET(request);
    const data = await response.json();

    expect(response.status).toBe(200);
    expect(data.success).toBe(true);
    expect(Array.isArray(data.data)).toBe(true);
  });

  it('validates query parameters', async () => {
    const request = new NextRequest(
      'http://localhost/api/markets?limit=invalid'
    );
    const response = await GET(request);

    expect(response.status).toBe(400);
  });

  it('handles database errors gracefully', async () => {
    // Mock database failure
    const request = new NextRequest('http://localhost/api/markets');
    // Test error handling
  });
});
```

### E2E Test Pattern (Playwright)

```typescript
import { test, expect } from '@playwright/test';

test('user can search and filter markets', async ({ page }) => {
  // Navigate to markets page
  await page.goto('/');
  await page.click('a[href="/markets"]');

  // Verify page loaded
  await expect(page.locator('h1')).toContainText('Markets');

  // Search for markets
  await page.fill('input[placeholder="Search markets"]', 'election');

  // Wait for debounce and results
  await page.waitForTimeout(600);

  // Verify search results displayed
  const results = page.locator('[data-testid="market-card"]');
  await expect(results).toHaveCount(5, { timeout: 5000 });

  // Verify results contain search term
  const firstResult = results.first();
  await expect(firstResult).toContainText('election', { ignoreCase: true });

  // Filter by status
  await page.click('button:has-text("Active")');

  // Verify filtered results
  await expect(results).toHaveCount(3);
});

test('user can create a new market', async ({ page }) => {
  // Login first
  await page.goto('/creator-dashboard');

  // Fill market creation form
  await page.fill('input[name="name"]', 'Test Market');
  await page.fill('textarea[name="description"]', 'Test description');
  await page.fill('input[name="endDate"]', '2025-12-31');

  // Submit form
  await page.click('button[type="submit"]');

  // Verify success message
  await expect(page.locator('text=Market created successfully')).toBeVisible();

  // Verify redirect to market page
  await expect(page).toHaveURL(/\/markets\/test-market/);
});
```

## Test File Organization

```
src/
├── components/
│   ├── Button/
│   │   ├── Button.tsx
│   │   ├── Button.test.tsx          # Unit tests
│   │   └── Button.stories.tsx       # Storybook
│   └── MarketCard/
│       ├── MarketCard.tsx
│       └── MarketCard.test.tsx
├── app/
│   └── api/
│       └── markets/
│           ├── route.ts
│           └── route.test.ts         # Integration tests
└── e2e/
    ├── markets.spec.ts               # E2E tests
    ├── trading.spec.ts
    └── auth.spec.ts
```

## Mocking External Services

### Supabase Mock

```typescript
jest.mock('@/lib/supabase', () => ({
  supabase: {
    from: jest.fn(() => ({
      select: jest.fn(() => ({
        eq: jest.fn(() =>
          Promise.resolve({
            data: [{ id: 1, name: 'Test Market' }],
            error: null,
          })
        ),
      })),
    })),
  },
}));
```

### Redis Mock

```typescript
jest.mock('@/lib/redis', () => ({
  searchMarketsByVector: jest.fn(() =>
    Promise.resolve([{ slug: 'test-market', similarity_score: 0.95 }])
  ),
  checkRedisHealth: jest.fn(() => Promise.resolve({ connected: true })),
}));
```

### OpenAI Mock

```typescript
jest.mock('@/lib/openai', () => ({
  generateEmbedding: jest.fn(() =>
    Promise.resolve(
      new Array(1536).fill(0.1) // Mock 1536-dim embedding
    )
  ),
}));
```

## Test Coverage Verification

### Run Coverage Report

```bash
npm run test:coverage
```

### Coverage Thresholds

```json
{
  "jest": {
    "coverageThresholds": {
      "global": {
        "branches": 80,
        "functions": 80,
        "lines": 80,
        "statements": 80
      }
    }
  }
}
```

## Common Testing Mistakes to Avoid

### ❌ WRONG: Testing Implementation Details

```typescript
// Don't test internal state
expect(component.state.count).toBe(5);
```

### ✅ CORRECT: Test User-Visible Behavior

```typescript
// Test what users see
expect(screen.getByText('Count: 5')).toBeInTheDocument();
```

### ❌ WRONG: Brittle Selectors

```typescript
// Breaks easily
await page.click('.css-class-xyz');
```

### ✅ CORRECT: Semantic Selectors

```typescript
// Resilient to changes
await page.click('button:has-text("Submit")');
await page.click('[data-testid="submit-button"]');
```

### ❌ WRONG: No Test Isolation

```typescript
// Tests depend on each other
test('creates user', () => {
  /* ... */
});
test('updates same user', () => {
  /* depends on previous test */
});
```

### ✅ CORRECT: Independent Tests

```typescript
// Each test sets up its own data
test('creates user', () => {
  const user = createTestUser();
  // Test logic
});

test('updates user', () => {
  const user = createTestUser();
  // Update logic
});
```

## Continuous Testing

### Watch Mode During Development

```bash
npm test -- --watch
# Tests run automatically on file changes
```

### Pre-Commit Hook

```bash
# Runs before every commit
npm test && npm run lint
```

### CI/CD Integration

```yaml
# GitHub Actions
- name: Run Tests
  run: npm test -- --coverage
- name: Upload Coverage
  uses: codecov/codecov-action@v3
```

## Best Practices

1. **Write Tests First** - Always TDD
2. **One Assert Per Test** - Focus on single behavior
3. **Descriptive Test Names** - Explain what's tested
4. **Arrange-Act-Assert** - Clear test structure
5. **Mock External Dependencies** - Isolate unit tests
6. **Test Edge Cases** - Null, undefined, empty, large
7. **Test Error Paths** - Not just happy paths
8. **Keep Tests Fast** - Unit tests < 50ms each
9. **Clean Up After Tests** - No side effects
10. **Review Coverage Reports** - Identify gaps

## Success Metrics

- 80%+ code coverage achieved
- All tests passing (green)
- No skipped or disabled tests
- Fast test execution (< 30s for unit tests)
- E2E tests cover critical user flows
- Tests catch bugs before production

---

**Remember**: Tests are not optional. They are the safety net that enables confident refactoring, rapid development, and production reliability.