Add new skills for backend patterns, coding standards, continuous learning, and NestJS best practices

- Introduced backend patterns skill with guidelines on API design, database optimization, and server-side best practices. - Added coding standards skill outlining universal coding principles for TypeScript, NestJS, and Node.js development. - Implemented continuous learning skill to automatically extract reusable patterns from Cursor sessions. - Created NestJS best practices skill detailing architecture patterns, dependency injection, error handling, and security measures. - Included various rules and templates for NestJS best practices to ensure production-ready applications.
2026-08-20 18:30:39 +07:00
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+---
+name: tdd-workflow
+description: 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.
+---
+
+# 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 (Supertest)
+- Critical API flows
+- Complete HTTP workflows
+- Auth, validation, and error responses
+
+## 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 (Supertest)
+```typescript
+import { INestApplication } from '@nestjs/common'
+import { Test } from '@nestjs/testing'
+import request from 'supertest'
+import { AppModule } from '../src/app.module'
+
+describe('Users (e2e)', () => {
+  let app: INestApplication
+
+  beforeAll(async () => {
+    const moduleRef = await Test.createTestingModule({
+      imports: [AppModule],
+    }).compile()
+
+    app = moduleRef.createNestApplication()
+    await app.init()
+  })
+
+  afterAll(async () => {
+    await app.close()
+  })
+
+  it('POST /users creates a user', async () => {
+    await request(app.getHttpServer())
+      .post('/users')
+      .send({ email: 'ada@example.com', password: 'secret123' })
+      .expect(201)
+  })
+})
+```
+
+## Test File Organization
+
+```
+src/
+└── modules/
+    └── users/
+        ├── users.module.ts
+        ├── users.controller.ts
+        ├── users.controller.spec.ts   # Unit tests
+        ├── users.service.ts
+        ├── users.service.spec.ts
+        └── dto/
+test/
+├── jest-e2e.json
+├── app.e2e-spec.ts                    # E2E tests
+└── users.e2e-spec.ts
+```
+
+## Mocking External Services
+
+### Drizzle Mock
+```typescript
+const db = {
+  query: {
+    users: {
+      findFirst: jest.fn(),
+      findMany: jest.fn(),
+    },
+  },
+  insert: jest.fn(),
+  update: jest.fn(),
+  delete: jest.fn(),
+}
+```
+
+### 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.