Deno Unit Tests In GitHub Actions CI

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Deno Unit Tests in GitHub Actions CI

Let's dive into how to enhance your GitHub Actions CI/CD pipeline by adding Deno unit tests. This ensures code quality through automated testing before merging or deploying. Currently, our workflow (defined in .github/workflows/deploy.yml) only covers deployment. We're going to supercharge it by introducing a test job that automatically runs Deno unit tests. This is all about catching those pesky bugs early and keeping our codebase healthy!

Why Unit Tests are a Game Changer

Unit tests are fundamental to robust software development. They act as your first line of defense, validating that individual components of your application work as expected. By writing and running unit tests, you gain confidence in your code, reduce the risk of introducing bugs, and make it easier to refactor and maintain your project over time. Think of them as mini-quality checks that give you peace of mind.

By integrating automated unit testing into your CI/CD pipeline, you ensure that every code change is automatically tested before it's merged or deployed. This helps you catch bugs early in the development process, preventing them from making their way into production. Plus, it provides rapid feedback to developers, allowing them to quickly identify and fix issues.

Testing is more than just a chore; it’s an investment in the long-term health of your project. A well-tested codebase is easier to understand, modify, and extend, leading to increased productivity and reduced maintenance costs. So, let’s get those tests rolling!

Acceptance Criteria

Before we start, let's outline what needs to be done to consider this task complete. These are our goals:

  1. Modify .github/workflows/deploy.yml: We'll be tweaking this file to add our new test job.
  2. Add a test Job: A new job named test (or unit-test) will be created in our workflow.
  3. Deno CLI Execution: This job will use the Deno CLI (e.g., deno test --allow-all) to run all *.test.ts files in the src/ directory.
  4. Job Dependency: The deploy-functions job will only run after the test job succeeds (needs: test).
  5. Workflow Trigger: The workflow should trigger the test job on pull_request events to the main branch.

Step-by-Step Implementation

Let’s break down how to implement these acceptance criteria, making it easy to follow along.

1. Modifying .github/workflows/deploy.yml

First, you'll need to open up your .github/workflows/deploy.yml file in your project. This file is where your CI/CD workflow is defined. We're going to add a new job to this file that will run our Deno unit tests.

2. Adding the test Job

Now, let's add the test job to the workflow. This job will be responsible for running our unit tests. Here’s what the job definition might look like:

test:
  runs-on: ubuntu-latest
  steps:
    - name: Checkout code
      uses: actions/checkout@v3

    - name: Set up Deno
      uses: denoland/setup-deno@v1
      with:
        deno-version: v1.x

    - name: Run tests
      run: deno test --allow-all src/

In this snippet:

  • runs-on: ubuntu-latest specifies that the job will run on an Ubuntu virtual machine.
  • actions/checkout@v3 checks out your code into the virtual machine.
  • denoland/setup-deno@v1 sets up the Deno environment.
  • deno test --allow-all src/ executes the Deno test runner, running all *.test.ts files in the src/ directory. The --allow-all flag grants all permissions to the test code, which might be necessary depending on your tests.

3. Setting Up Job Dependencies

We want to make sure that our deployment job only runs if the tests pass. To do this, we'll add a needs field to the deploy-functions job, like so:

deploy-functions:
  needs: test
  runs-on: ubuntu-latest
  # ... rest of your deployment steps ...

This tells GitHub Actions that the deploy-functions job depends on the test job and will only run if the test job completes successfully.

4. Updating the Workflow Trigger

Finally, we want to make sure that our test job runs whenever a pull request is made to the main branch. To do this, we'll update the on field in our workflow file:

on:
  push:
    branches: [ main ]
  pull_request:
    branches: [ main ]

This configuration tells GitHub Actions to run the workflow whenever code is pushed to the main branch or when a pull request is made against the main branch. This way, you get immediate feedback on your code changes.

Putting It All Together

Here's what the complete .github/workflows/deploy.yml file might look like:

name: Deploy

on:
  push:
    branches: [ main ]
  pull_request:
    branches: [ main ]

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v3

      - name: Set up Deno
        uses: denoland/setup-deno@v1
        with:
          deno-version: v1.x

      - name: Run tests
        run: deno test --allow-all src/

  deploy-functions:
    needs: test
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v3

      # ... rest of your deployment steps ...

Testing Principles

Refer to AGENTS.md and docs/ARCHITECTURE.md for testing guidelines. The test command should use Deno's built-in test runner.

Best Practices and Considerations

  • Granular Tests: Write small, focused tests that target individual units of code. This makes it easier to identify the source of failures and improves the overall maintainability of your test suite.
  • Descriptive Test Names: Give your tests descriptive names that clearly indicate what they are testing. This makes it easier to understand the purpose of each test and helps you quickly identify failing tests.
  • Test Coverage: Aim for high test coverage, but don't obsess over it. Focus on testing the most critical parts of your application and the areas that are most likely to contain bugs.
  • Mocking and Stubbing: Use mocking and stubbing techniques to isolate the code under test from its dependencies. This allows you to test your code in isolation and avoid relying on external systems or databases.
  • Continuous Integration: Integrate your unit tests into your CI/CD pipeline to automatically run them whenever code changes are made. This helps you catch bugs early and prevent them from making their way into production.
  • Permissions: Always be mindful of the permissions you grant to your test code. Use the --allow-all flag sparingly and only when necessary. Consider using more specific permission flags to limit the scope of permissions granted to your tests.

Troubleshooting Common Issues

  • Tests Failing: If your tests are failing, carefully examine the error messages and stack traces to identify the source of the problem. Use debugging techniques to step through your code and understand what's going wrong.
  • Deno Setup Issues: If you're having trouble setting up Deno in your GitHub Actions workflow, double-check that you're using the correct version of the denoland/setup-deno action and that you've configured it correctly.
  • Permission Errors: If you're encountering permission errors, make sure that you're granting the necessary permissions to your test code. Use the --allow-all flag or more specific permission flags as needed.
  • Slow Tests: If your tests are running slowly, try to optimize your code and reduce the amount of time it takes to run each test. Consider using parallel testing techniques to run multiple tests simultaneously.

Conclusion

Alright, guys, we've successfully added a Deno unit test job to our GitHub Actions CI/CD pipeline! By following these steps, you've ensured that your code is automatically tested before it's merged or deployed, helping you catch bugs early and improve the overall quality of your application. High-five! This not only boosts code reliability but also streamlines your development workflow. Keep those tests green, and your deployments smooth!