test-github-actions

Test GitHub Actions with act

This Skill helps you test GitHub Actions workflows locally using the act tool, allowing you to validate workflow changes before pushing to GitHub and catch issues early.

When to use this Skill

Automatically activate this Skill when:

• User is modifying files in .github/workflows/
• User mentions testing GitHub Actions, workflows, or CI/CD
• User asks to validate changes before pushing
• User mentions the act tool
• There's a GitHub Actions workflow failure that needs debugging
• User is creating a new workflow file

Prerequisites

1. Check if act is installed

act --version

If not installed:

• macOS: brew install act
• Linux: See https://github.com/nektos/act#installation
• Windows: See https://github.com/nektos/act#installation

2. Verify Docker is running

act requires Docker to run workflow containers. If Docker is not running, inform the user and provide instructions to start it.

3. Ensure act configuration exists

Check for ~/Library/Application Support/act/actrc (macOS) or ~/.actrc (Linux/Windows).

If missing, create it with:

-P ubuntu-latest=catthehacker/ubuntu:act-latest

This configures act to use the medium Docker image (~500MB) which includes necessary tools for most workflows.

Testing workflow process

Follow these steps in order:

Step 1: Identify the workflow to test

If the user hasn't specified which workflow to test:

# List all workflows
act -l

Then either:

• Ask the user which workflow to test
• Look at recent file changes to suggest which workflow might be affected:

  git diff --name-only | grep ".github/workflows/"
  

Step 2: Perform a dry-run first

Always start with a dry-run to validate workflow syntax quickly:

act -W .github/workflows/{workflow-file}.yml -j {job-name} --dryrun

The dry-run will:

• Validate YAML syntax
• Check workflow structure
• Show which steps would execute
• Complete in seconds

Step 3: Run the full workflow

If dry-run succeeds, execute the actual workflow:

act -W .github/workflows/{workflow-file}.yml -j {job-name} --container-architecture linux/amd64

Important flags:

• --container-architecture linux/amd64: Required on Apple Silicon Macs
• -W .github/workflows/{file}: Specify exact workflow file
• -j {job-name}: Specify job to run (get from act -l output)

Note on execution time:

• First run may take 5-10 minutes (downloading Docker images)
• Subsequent runs are much faster (images cached)

Step 4: Analyze the results

Review the output and categorize issues:

✅ Successful steps

• Dependency installation completed
• Scripts executed without errors
• Tests passed

❌ Real failures (must fix)

• Missing dependencies in package.json
• Script errors or syntax issues
• Failed tests
• Configuration problems

⚠️ Expected act limitations (can ignore)

• Git operations failing in worktrees: fatal: not a git repository
• PR creation failures: Missing GitHub secrets
• Actions requiring GitHub context that isn't available locally

Step 5: Provide recommendations

Based on results, tell the user:

If only expected failures:

✅ Workflow validation passed! The core logic works correctly.
The only failures were expected act limitations (git operations, PR creation).
Safe to commit and push your changes.

If real failures exist:

❌ Found issues that need fixing:
1. [Specific issue with file:line reference]
2. [Another issue]

Fix these before committing.

If fixes were made: Offer to re-run the workflow to verify the fixes.

Known limitations of act

Be aware of these limitations when interpreting results:

Git operations in worktrees

• Symptom: fatal: not a git repository: .git/worktrees/...
• Why: act has trouble with git worktrees
• Action: Ignore this error - it works fine in real GitHub Actions

Missing secrets

• Symptom: Steps that need secrets.GITHUB_TOKEN or other secrets are skipped
• Why: act doesn't have access to GitHub secrets
• Action: Expected behavior - secrets work in real GitHub Actions

PR creation actions

• Symptom: PR creation steps fail
• Why: Requires GitHub API access and secrets
• Action: Expected - these work in real GitHub Actions

Action compatibility

• Symptom: Some actions behave differently
• Why: Local Docker environment vs GitHub's hosted runners
• Action: Test the core workflow logic; some differences are acceptable

Examples

Example 1: Test after modifying a workflow

User says: "I just updated the bullish-docs-update workflow, can we test it?"

Response:

1. Check act is installed
2. Run dry-run: act -W .github/workflows/bullish-docs-update.yml -j update-docs --dryrun
3. If successful, run full test with --container-architecture linux/amd64
4. Report results with specific pass/fail for each step
5. Recommend whether safe to commit

Example 2: Debug a workflow failure

User says: "The Binance workflow is failing in GitHub Actions, let's test it locally"

Response:

1. Run the workflow with act
2. Compare local results with GitHub Actions logs
3. Identify if it's a real issue or environment difference
4. Suggest fixes based on the specific failure

Example 3: Proactive suggestion

User modifies .github/workflows/new-venue.yml

Proactively suggest: "I see you modified a GitHub Actions workflow. Would you like me to test it locally with act before you push? This will help catch any issues early."

Workflow validation checklist

When testing workflows, verify:

• All required dependencies are listed in package.json files
• Node.js version matches workflow configuration
• Install steps complete successfully (shared, venue-specific)
• Main script execution completes without errors
• Documentation is generated successfully
• No unexpected errors in step output

Tips for faster iteration

1. Cache Docker images: First run is slow, subsequent runs are fast
2. Test specific jobs: Use -j {job-name} instead of running all jobs
3. Use dry-run first: Quickly validate syntax before full execution
4. Watch for patterns: Similar workflows often have similar issues

Platform-specific notes

macOS (Apple Silicon)

• Always use --container-architecture linux/amd64
• Docker Desktop must be running
• Config file location: ~/Library/Application Support/act/actrc

macOS (Intel)

• Usually doesn't need --container-architecture flag
• Docker Desktop must be running

Linux

• Config file location: ~/.actrc
• Ensure Docker daemon is running: sudo systemctl status docker

Troubleshooting

"act: command not found"

Install act:

brew install act  # macOS
# or see https://github.com/nektos/act#installation

"Cannot connect to Docker daemon"

Start Docker Desktop (macOS) or Docker daemon (Linux):

# Linux
sudo systemctl start docker

"Error: pull access denied"

act needs to pull Docker images. Ensure:

• Docker is running
• Internet connection is available
• actrc is configured with the correct image

Workflow takes too long

• First run downloads images (~500MB) - this is normal
• Subsequent runs use cached images and are much faster
• You can interrupt with Ctrl+C if needed

Remember

• act tests the workflow logic, not the exact GitHub Actions environment
• Some failures are expected and can be ignored (git operations, secrets)
• The goal is to catch real issues (missing dependencies, script errors) before pushing
• Always provide clear guidance on whether changes are safe to push