Run Unit Testing Job using a Service

In this guide, we’ll show you how to spin up a non-production MongoDB service container alongside your GitHub Actions workflow. By configuring a service container, you isolate test data from your production instance and ensure reliable, repeatable unit tests.

Note

Service containers are Docker containers that run in parallel with your job, providing databases, caches, or other dependencies in an isolated environment.

The image shows a GitHub documentation page about service containers, explaining their use in connecting databases, web services, and other tools in workflows. The page includes navigation links and a note about using Docker containers.

1. Base Workflow Configuration

Here’s our existing workflow using a production MongoDB instance. We need to replace it with a test container:

name: Solar System Workflow

on:
  workflow_dispatch:
  push:
    branches:
      - main
      - 'feature/*'

env:
  MONGO_URI: mongodb+srv://supercluster.d83jj.mongodb.net/superData
  MONGO_USERNAME: ${{ vars.MONGO_USERNAME }}
  MONGO_PASSWORD: ${{ secrets.MONGO_PASSWORD }}

jobs:
  unit-testing: ...
  code-coverage: ...
  docker: ...

2. Configuring MongoDB as a Service Container

We’ll use the pre-built image siddharth67/mongo-db:non-prod from Docker Hub. Add a services section to your unit-testing job:

jobs:
  unit-testing:
    name: Unit Testing
    runs-on: ubuntu-latest

    services:
      mongo-db:
        image: siddharth67/mongo-db:non-prod
        ports:
          - 27017:27017

    strategy:
      matrix:
        nodejs_version: [18, 20]
        operating_system: [ubuntu-latest]
        exclude:
          - nodejs_version: 18
            operating_system: macos-latest

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

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

Mapping port 27017 on the host to the container lets your tests connect via localhost:27017.

3. Overriding Environment Variables

Job-level environment variables override global settings. Point your test suite at the local MongoDB service:

jobs:
  unit-testing:
    # ... (services config)

    env:
      MONGO_URI: 'mongodb://localhost:27017/superData'
      MONGO_USERNAME: non-prod-user
      MONGO_PASSWORD: non-prod-password

    # ... (strategy & steps)

Note

Job-level env entries take precedence over workflow-level env values.

Commit and push to trigger the updated workflow.

4. Initialization Behind the Scenes

During the initialize containers step, GitHub Actions:

Creates an isolated Docker network
Pulls the service image
Launches the container and maps its ports
Waits for any health checks to pass

/usr/bin/docker ps --filter id=... --no-trunc --format "{{.ID}}"
/usr/bin/docker inspect --format "{{if .Config.Healthcheck}}{{print .State.Health.Status}}{{end}}"

The image shows a GitHub Actions workflow interface with a unit testing job running on Ubuntu. It displays logs and details of the setup and initialization process.

5. Fixing Connection String Errors

If you encounter:

MongoParseError: Invalid connection string

ensure your URI starts with the correct scheme:

env:
  MONGO_URI: 'mongodb://localhost:27017/superData'

Warning

Check for typos and ensure mongodb:// (not mongodb+srv://) when connecting to a local container.

You can also update to the latest setup-node action:

- name: Setup Node.js ${{ matrix.nodejs_version }}
  uses: actions/setup-node@v4
  with:
    node-version: ${{ matrix.nodejs_version }}

Push your fixes and rerun the workflow.

6. Successful Run

A successful unit-testing job looks like this:

npm test
shell: /usr/bin/bash -e {0}
env:
  MONGO_URI: mongodb://localhost:27017/superData
  MONGO_USERNAME: non-prod-user
  MONGO_PASSWORD: non-prod-password
Solar [email protected] test
mocha app-test.js --timeout 10000 --reporter mocha-junit-reporter --exit
Server successfully running on port - 3000

The image shows a GitHub Actions workflow interface with a "modified mongo uri" workflow in progress, displaying completed unit testing and code coverage jobs.

Your tests now run against a dedicated non-production MongoDB container, keeping real data safe and test environments reproducible.

References

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