Unit Tests workflow (saintslab/carbontracker)

The Unit Tests workflow from saintslab/carbontracker, explained and optimized by Latchkey.

What it does

This is the Unit Tests workflow from the saintslab/carbontracker repository, a real project running GitHub Actions. It is shown here with attribution under its MIT license.

Below, Latchkey shows a faster, safer version produced by its optimization engine.

The workflow

name: Unit Tests

on:
  push:
    branches:
      - master
      - dev
  pull_request:
    branches:
      - master
      - dev

jobs:
  test:
    runs-on: ubuntu-22.04
    strategy:
      matrix:
        python-version: ['3.7.17', '3.8.18','3.9.21', '3.10.16', '3.11.11', '3.12.9'] # Latest version available for each. Ref: https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json

    steps:
    - uses: actions/checkout@v3
    - name: Set up Python ${{ matrix.python-version }}
      uses: actions/setup-python@v5
      with:
        python-version: ${{ matrix.python-version }}
    - name: Install dependencies
      run: |
        python -m pip install --upgrade pip
        pip install flake8 black
        if [ "${{ matrix.python-version }}" = "3.9.21" ]; then
          pip install pyfakefs==4.5.1
        else
          pip install pyfakefs==5.8.0
        fi
        pip install .[test]
    - name: Lint with flake8
      run: |
        flake8 carbontracker --count --select=E9,F63,F7,F82 --show-source --statistics
    - name: Formatting with Black
      run: black --line-length 120 carbontracker
    - name: Run tests
      run: python -m unittest discover -v

The same workflow, on Latchkey

Estimated ~20% faster on cache hits, plus fewer wasted runs and a safer supply chain. Added and changed lines are highlighted.

name: Unit Tests
 
on:
  push:
    branches:
      - master
      - dev
  pull_request:
    branches:
      - master
      - dev
 
concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true
 
jobs:
  test:
    timeout-minutes: 30
    runs-on: latchkey-small
    strategy:
      matrix:
        python-version: ['3.7.17', '3.8.18','3.9.21', '3.10.16', '3.11.11', '3.12.9'] # Latest version available for each. Ref: https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json
 
    steps:
    - uses: actions/checkout@v3
    - name: Set up Python ${{ matrix.python-version }}
      uses: actions/setup-python@v5
      with:
        cache: 'pip'
        python-version: ${{ matrix.python-version }}
    - name: Install dependencies
      run: |
        python -m pip install --upgrade pip
        pip install flake8 black
        if [ "${{ matrix.python-version }}" = "3.9.21" ]; then
          pip install pyfakefs==4.5.1
        else
          pip install pyfakefs==5.8.0
        fi
        pip install .[test]
    - name: Lint with flake8
      run: |
        flake8 carbontracker --count --select=E9,F63,F7,F82 --show-source --statistics
    - name: Formatting with Black
      run: black --line-length 120 carbontracker
    - name: Run tests
      run: python -m unittest discover -v
 

What changed

• Run on Latchkey managed runners with one line (runs-on), which apply the fixes below automatically and self-heal transient failures. This example uses latchkey-small; pick the runner size that fits the job.
• Cancel superseded runs when a branch or PR gets a newer push.
• Cache dependency installs on the setup step so they are served from cache.
• Add a job timeout so a hung step cannot burn hours of runner time.

What Latchkey heals here

This workflow has steps that commonly fail on transient issues (network, registries, flaky browsers). On Latchkey managed runners they are detected, retried, and self-healed instead of failing your build:

• Dependency installs

This workflow runs 1 job (6 with the matrix expanded) per trigger. On Latchkey the same minutes cost up to 58% less than GitHub-hosted, with zero queue time.

Actions used in this workflow