Run Code Coverage Job using a Container and Service

In this guide, you’ll learn how to set up a code coverage workflow in GitHub Actions by combining a job container with a MongoDB service container. This approach ensures all steps run in a consistent environment and can connect to your database service seamlessly.

1. Recap: Unit Testing with a Service Container

Below is a sample job that runs unit tests in Node.js while using a MongoDB service container:

jobs:
  unit-testing:
    name: Unit Testing
    runs-on: ${{ matrix.operating_system }}
    services:
      mongo-db:
        image: siddharth67/mongo-db:non-prod
        ports:
          - 27017:27017
        env:
          MONGO_URI: "mongodb://localhost:27017/superData"
          MONGO_USERNAME: non-prod-user
          MONGO_PASSWORD: non-prod-password
    strategy:
      matrix:
        nodejs_version: [18, 20]
        operating_system: [ubuntu-latest]
        exclude:
          - nodejs_version: 18
            operating_system: macos-latest
    steps:
      - uses: actions/checkout@v4
        name: Checkout Repository

      - uses: actions/setup-node@v3
        name: Setup Node.js ${{ matrix.nodejs_version }}
        with:
          node-version: ${{ matrix.nodejs_version }}

      - uses: actions/cache@v3
        name: Cache npm Dependencies
        with:
          path: node_modules
          key: ${{ runner.os }}-node-modules-${{ hashFiles('package-lock.json') }}

      - run: npm install
        name: Install Dependencies

      - run: npm test
        id: nodejs-unit-testing-step
        name: Run Unit Tests

      - if: always()
        uses: actions/upload-artifact@v3
        name: Archive Test Results
        with:
          name: Mocha-Test-Result
          path: test-results.xml

2. What Is a Job Container?

A job container allows you to execute every step of a job inside a specified Docker image instead of on the default runner VM. This ensures your CI environment matches production more closely.

(See: https://docs.github.com/en/actions/using-jobs/running-jobs-in-a-container)

jobs:
  example-job:
    runs-on: ubuntu-latest
    container:
      image: node:18
    steps:
      - name: Verify Docker Environment
        run: |
          if [ -f ./dockerenv ]; then
            echo "Found dockerenv"
          else
            echo "No dockerenv"
          fi

3. Defining the Code Coverage Workflow

The following workflow runs a code coverage job in a Node.js 18 container and attaches a MongoDB service container for database operations:

name: CI
on:
  push:
    branches: [ main ]

jobs:
  code-coverage:
    name: Code Coverage
    runs-on: ubuntu-latest
    container:
      image: node:18
    services:
      mongo-db:
        image: siddharth67/mongo-db:non-prod
        options: --name mongo
    env:
      MONGO_URI: 'mongodb://mongo:27017/superData'
      MONGO_USERNAME: non-prod-user
      MONGO_PASSWORD: non-prod-password

    steps:
      - uses: actions/checkout@v4
        name: Checkout Repository

      - uses: actions/cache@v3
        name: Cache npm Dependencies
        with:
          path: node_modules
          key: ${{ runner.os }}-node-modules-${{ hashFiles('package-lock.json') }}

      - run: npm install
        name: Install Dependencies

      - run: npm run coverage
        name: Run Code Coverage

4. Verify and Inspect Logs

After committing and pushing your workflow, navigate to the Actions tab in GitHub. You should see both the Unit Testing and Code Coverage jobs running in parallel.

In the logs, you’ll find Docker commands demonstrating how GitHub Actions starts both the job and service containers:

/usr/bin/docker start 99621c88b3e11e3a36090a1a87149e466bf5e8479ab5a54185f073369248
/usr/bin/docker create --name mongo --network github_network \
  -e GITHUB_ACTIONS=true -e CI=true sidharth67/mongo-db:non-prod

Links and References

• Running jobs in a container (GitHub Docs)
• GitHub Actions: Workflow Syntax
• MongoDB Docker Hub