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Advanced testing automation strategies with GitHub Actions

Bekah Whittle
Bekah Whittle // Director, Field Services // GitHub

Testing becomes more challenging as projects expand and become more intricate. GitHub Actions offers a range of testing styles and a rich marketplace tailored to large-scale needs. This guide outlines advanced testing strategies with Actions, highlighting its potential to tackle scalability issues effectively. Stack Overflow joins us again to discuss the workflow optimizations that have streamlined their operations.

In this guide, you will learn:

  •  How to navigate and leverage GitHub Marketplace for advanced testing needs

  •  Methods for accelerating test timelines through matrix configurations

  •  How to optimize your workflow with the 'strategy' keyword and runner size selection

Utilizing the marketplace

GitHub Marketplace serves as a powerful tool for those looking to amplify their testing capabilities, enabling users to tap into a plethora of testing solutions tailored to diverse needs. Whether you're jumping into unit testing, security checks, linting, or specialized tests for platforms like iOS and Android, Marketplace has tools designed for your specific requirement.

Moreover, the community-driven nature of Marketplace ensures a continual influx of tools and actions, each aiming to address unique testing scenarios. By navigating through Marketplace, users can discover and integrate these tools, thereby enhancing their testing strategies and ensuring comprehensive coverage.

The power of matrices in scaling testing

Matrices in Actions let you test on different systems and software versions all at once. This speeds up your testing and makes sure your software works in different settings.

For example, you can use matrices to test your software on both Windows and Ubuntu, using different software versions, all at the same time. This saves time and confirms that your software works well in various setups.

The main benefit of using matrices is speed. Your tests run at the same time, not one after the other, making the whole process faster and getting you quick feedback.

In the example below, we define a strategy with a matrix that contains two arrays: version and os

        version: [10, 12, 14]
        os: [ubuntu-latest, windows-latest]

This setup will automatically generate six different combinations of version and os as shown:

{version: 10, os: ubuntu-latest}
{version: 10, os: windows-latest}
{version: 12, os: ubuntu-latest}
{version: 12, os: windows-latest}
{version: 14, os: ubuntu-latest}
{version: 14, os: windows-latest}

These combinations run in parallel, allowing you to test across multiple software versions and operating systems simultaneously. This dramatically accelerates testing time and provides comprehensive coverage.

We use dynamic matrices in GitHub Actions to set up test environments that are tailored to individual pull requests (PRs). When team members create a PR, they can apply specific labels to indicate the type of test environment required—whether it's the public platform, Stack Overflow for Teams, or a unique configuration. We then automatically generate a dynamic matrix based on the labels and use that to set up the precise environment needed for testing. This matrix can even be used to populate the environment with specific data subsets, allowing for more robust and meaningful integration tests. This approach helps accelerate our development cycles, reduce errors, and ensure that we deliver a reliable and high-quality product.

Jason Schwanz
Jason Schwanz // Staff Site Reliability Engineer // Stack Overflow

Establishing the testing 'strategy'

The strategy keyword is pivotal for enterprise-scale testing. It provides a structured approach to define and manage workflows tailored to complex projects. One notable keyword under strategy is fail fast. It's designed for efficiency, stopping a test as soon as a failure is detected, saving precious time and resources. For enterprises juggling multiple platforms, strategy also enables the simultaneous testing across different operating systems and versions, ensuring robust compatibility and coverage.

Select runner size

Selecting the right runner size is a balance. It's about ensuring the test completes quickly without overburdening or underutilizing resources. For instance, while a 2-core runner might suffice for lightweight tasks, intensive tests might necessitate an 8-core runner to achieve timely results.

For enterprise decision-makers, the key lies in understanding the nature of the tests and aligning runner size accordingly, optimizing both time and resources.

At Stack Overflow, we manage all runner groups at the Enterprise level to keep things simple, especially since we’re a small team overseeing a large GitHub footprint. We recommend focusing on runner capacity; for example, we have a runner group specifically for resource-heavy tasks like functional tests that require large runners. Then, when we experiment or work on proof of concept projects, we avoid using runners in this group to control costs.

Jason Schwanz
Jason Schwanz // Staff Site Reliability Engineer // Stack Overflow

Up next: Advanced deployment strategies in GitHub Actions

Ready for the next step? Our following guide on advanced deployment with GitHub Actions will teach you scalable deployment strategies.