Local CI testing with act would help reduce PR failures

[attackordie]

Local CI testing with act would help reduce PR failures

Problem

Developers experience a common issue: local tests pass but GitHub CI fails. The current Justfile only provides basic commands:

test:                 # Only runs cargo test + doc tests
build:                # Only builds main binary  
build-examples:       # Builds examples

Missing CI checks that cause PR failures:

• License header validation (./scripts/copyright.sh)
• Code formatting (cargo +nightly fmt --check)
• Linting (cargo clippy)
• Security audit (cargo audit, cargo deny)
• Spell checking (typos)

This creates frustrating development cycles where developers push believing code is ready, only to have CI fail on formatting or tooling issues.

Proposed Solution

Add [act](https://github.com/nektos/act) integration to run GitHub Actions workflows locally. act uses the exact same .github/workflows/rust.yml file as GitHub CI, ensuring perfect parity with zero configuration drift.

Benefits

For Developers:

• Catch CI failures before pushing
• Test individual CI jobs (lint, security, etc.)
• Always matches latest workflow changes

For Maintainers:

• Fewer failing PRs
• Reduced review overhead on CI-related issues

Implementation

Add these commands to the Justfile:

# Install act tool
act-install:
    curl https://raw.githubusercontent.com/nektos/act/master/install.sh | sudo bash

# Run individual CI jobs locally
act-lint:
    act -W ./.github/workflows/rust.yml -j lint --rm

act-build:
    act -W ./.github/workflows/rust.yml -j build --rm

act-security:
    act -W ./.github/workflows/rust.yml -j security --rm

# Run all CI jobs
act-ci-all:
    act -W ./.github/workflows/rust.yml --rm

Developer Workflow

Before:

$ just test          # Only runs cargo test
$ git push           # Push to GitHub
# CI fails - formatting, linting issues
$ git commit --fixup # Fix CI issues

After:

$ just test          # Quick local tests
$ just act-lint      # Run exact GitHub linting
$ git push           # Push with confidence

Why act?

act uses the same Docker containers and workflow files as GitHub Actions, eliminating environment differences that cause local tests to pass while CI fails. It reads directly from .github/workflows/rust.yml, ensuring the same tests run locally and on GitHub. When new CI jobs are added to the workflow, corresponding Justfile commands can be added to expose them locally.

Implementation Details

• Requires Docker (for act containers)
• Backward compatible - all existing commands unchanged
• Uses act- prefix to avoid conflicts
• Optional adoption - developers can use incrementally

This addresses a real developer pain point while reducing maintainer overhead and improving project quality.