feat: Add comprehensive test suite for curriculum and progress services (#646)

- Add unit tests for curriculum service with >90% coverage
- Add unit tests for progress service with >90% coverage
- Add integration tests covering full API workflows
- Create comprehensive testing documentation
- Add jest setup configuration
- Add GitHub Actions CI workflow for automated testing
- Fix duplicate test script in package.json

Tests cover:
- Cache hit/miss scenarios
- Database fallback resilience
- Difficulty filtering
- Progress tracking and lesson completion
- Percentage calculations
- Student isolation
- Authentication and authorization
- End-to-end user journeys

Educational comments included throughout for learning purposes.

Closes #609

Author: boseshittu2323-design

.github/workflows/backend-tests.yml

@@ -0,0 +1,108 @@
+name: Backend Tests
+
+on:
+  push:
+    branches: [ main, develop ]
+    paths:
+      - 'backend/**'
+      - '.github/workflows/backend-tests.yml'
+  pull_request:
+    branches: [ main, develop ]
+    paths:
+      - 'backend/**'
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [18.x, 20.x]
+
+    services:
+      postgres:
+        image: postgres:15
+        env:
+          POSTGRES_USER: test
+          POSTGRES_PASSWORD: test
+          POSTGRES_DB: test_db
+        options: >-
+          --health-cmd pg_isready
+          --health-interval 10s
+          --health-timeout 5s
+          --health-retries 5
+        ports:
+          - 5432:5432
+
+      redis:
+        image: redis:7
+        options: >-
+          --health-cmd "redis-cli ping"
+          --health-interval 10s
+          --health-timeout 5s
+          --health-retries 5
+        ports:
+          - 6379:6379
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - name: Setup Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ matrix.node-version }}
+          cache: 'npm'
+          cache-dependency-path: backend/package-lock.json
+
+      - name: Install dependencies
+        working-directory: ./backend
+        run: npm ci
+
+      - name: Run Prisma generate
+        working-directory: ./backend
+        env:
+          DATABASE_URL: postgresql://test:test@localhost:5432/test_db
+        run: npx prisma generate
+
+      - name: Run database migrations
+        working-directory: ./backend
+        env:
+          DATABASE_URL: postgresql://test:test@localhost:5432/test_db
+        run: npx prisma migrate deploy || true
+
+      - name: Run tests with coverage
+        working-directory: ./backend
+        env:
+          NODE_ENV: test
+          DATABASE_URL: postgresql://test:test@localhost:5432/test_db
+          REDIS_URL: redis://localhost:6379
+          JWT_SECRET: test-jwt-secret
+        run: npm run test:coverage
+
+      - name: Check coverage threshold
+        working-directory: ./backend
+        run: |
+          coverage=$(cat coverage/coverage-summary.json | jq '.total.lines.pct')
+          echo "Coverage: $coverage%"
+          if (( $(echo "$coverage < 90" | bc -l) )); then
+            echo "❌ Coverage $coverage% is below 90% threshold"
+            exit 1
+          fi
+          echo "✅ Coverage $coverage% meets the 90% threshold"
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v3
+        with:
+          files: ./backend/coverage/lcov.info
+          flags: backend
+          name: backend-coverage
+          fail_ci_if_error: false
+
+      - name: Comment PR with coverage
+        if: github.event_name == 'pull_request'
+        uses: romeovs/lcov-reporter-action@v0.3.1
+        with:
+          lcov-file: ./backend/coverage/lcov.info
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          delete-old-comments: true

backend/jest.setup.js

@@ -0,0 +1,5 @@
+// Jest setup file for global test configuration
+process.env.NODE_ENV = 'test';
+process.env.DATABASE_URL = 'postgres://dummy:dummy@localhost:5432/dummy';
+process.env.JWT_SECRET = 'test-secret-key';
+process.env.REDIS_URL = 'redis://localhost:6379';

backend/package.json

@@ -8,10 +8,8 @@
     "start": "node dist/src/index.js",
     "start:prod": "node dist/src/index.js",
     "dev": "tsx watch src/index.ts",
-    "test": "jest --runInBand",
-    "test:coverage": "jest --coverage --runInBand",
-    "collaboration": "tsx src/collaborationServer.ts",
-    "test": "DATABASE_URL='postgres://dummy:dummy@localhost:5432/dummy' node --experimental-vm-modules node_modules/jest/bin/jest.js"
+    "test": "NODE_ENV=test jest --runInBand",
+    "test:coverage": "NODE_ENV=test jest --coverage --runInBand",
     "collaboration": "tsx src/collaborationServer.ts"
   },
   "keywords": [],