Enable Parallel Unity Tests: A Step-by-Step Guide

Hey guys! Let's dive into how we can speed up our Unity testing process using parallel workflows. This article will break down a recent patch that introduces parallel testing for Unity projects, making our development cycles faster and more efficient. We'll explore the benefits, the implementation details, and how you can integrate this into your own projects. Let's get started!

Understanding the Need for Parallel Testing

In today's fast-paced game development environment, efficient testing is crucial. Long test execution times can significantly slow down the development process. Traditional, sequential testing methods often mean waiting for one set of tests to complete before another can begin, which can be a major bottleneck. This is where parallel testing comes to the rescue. By running tests concurrently, we can dramatically reduce the overall time spent on testing, allowing developers to iterate more quickly and maintain a higher level of code quality.

Parallel testing involves running multiple test suites simultaneously, leveraging the power of modern multi-core processors and continuous integration (CI) systems. Imagine running your EditMode tests and PlayMode tests at the same time instead of one after the other. This not only saves time but also provides faster feedback, enabling developers to identify and fix issues sooner. The key benefit here is the significant reduction in test execution time, leading to quicker release cycles and more stable products. Implementing parallel testing requires careful configuration of your CI pipeline, but the payoff in terms of time saved and improved developer productivity makes it well worth the effort.

One of the primary advantages of parallel testing workflows is the ability to distribute the workload across multiple agents or runners in a CI environment. This means that different test suites, such as EditMode and PlayMode tests in Unity, can be executed concurrently, maximizing the utilization of available resources. For example, if you have a large suite of PlayMode tests that take a considerable amount of time to run, you don't have to wait for them to finish before starting your EditMode tests. By running them in parallel, you effectively cut down the total testing time to the duration of the longest test suite, rather than the sum of all test suite durations. This approach is particularly beneficial for large projects with extensive test suites, where the time savings can be substantial.

The New Parallel Test Workflow Patch

A recent patch introduces a new workflow file, unity-tests-parallel.yml, designed to enable parallel testing in Unity projects. This file configures the CI pipeline to run EditMode and PlayMode tests concurrently, significantly reducing the overall testing time. Let’s break down the key components of this patch and understand how it works.

The core of this patch is the unity-tests-parallel.yml file, which defines the workflow for running Unity tests in parallel. This file is structured to leverage GitHub Actions, a popular CI/CD platform, to automate the testing process. The file begins by specifying the workflow's name and the triggers that initiate the workflow. In this case, the workflow is triggered on pushes to the main branch, pull requests, and manual workflow dispatches. This ensures that tests are run automatically whenever code is updated or submitted for review. The workflow is then divided into two main jobs: editmode and playmode. These jobs are configured to run the respective test suites in parallel, utilizing separate runners on the CI system. This separation is crucial for achieving true parallelism, as it allows both sets of tests to execute simultaneously, rather than sequentially.

This patch introduces a parallel testing workflow for Unity projects, primarily through the addition of a new YAML file: unity-tests-parallel.yml. This file is designed to be used with GitHub Actions, a popular CI/CD platform, to automate the testing process. The workflow is structured into two main jobs: editmode and playmode. Each job is responsible for running a specific type of test within the Unity project. The editmode job focuses on tests that can be run within the Unity editor without requiring a built player. These tests typically cover editor scripts, custom tools, and other editor-specific functionality. The playmode job, on the other hand, runs tests that require a built player, simulating the runtime environment of the game. These tests are crucial for verifying gameplay mechanics, user interactions, and other runtime behaviors. By separating the tests into these two categories and running them in parallel, the workflow aims to significantly reduce the overall time spent on testing, providing faster feedback to developers.

Detailed Breakdown of the YAML Configuration

The unity-tests-parallel.yml file contains a detailed configuration that orchestrates the parallel testing process. Let's examine the key sections and their functionalities. Understanding this configuration is essential for customizing the workflow to fit your project's specific needs and ensuring that tests are run efficiently and reliably.

First, the name field specifies the name of the workflow, which is "Unity Tests (fast, parallel)". This name is displayed in the GitHub Actions interface, making it easy to identify the workflow. The on section defines the events that trigger the workflow. In this case, the workflow is triggered on push events to the main branch, pull_request events, and workflow_dispatch events. This means that the workflow will run automatically whenever code is pushed to the main branch, a pull request is created or updated, or the workflow is manually triggered. The jobs section is where the main logic of the workflow is defined. This section contains two jobs: editmode and playmode. Each job represents a separate set of tasks that will be executed in parallel. The editmode job is responsible for running EditMode tests, while the playmode job runs PlayMode tests. Each job includes several steps, such as checking out the code, caching the Library folder, running the tests, and uploading artifacts. These steps are executed in a specific order to ensure that the tests are run correctly and the results are captured for analysis.

EditMode Job

The editmode job is responsible for running tests that can be executed within the Unity editor without requiring a built player. This job is crucial for verifying the functionality of editor scripts, custom tools, and other editor-specific features. The configuration for this job includes several key steps that ensure the tests are run efficiently and the results are captured for analysis. The first step is to check out the code using the actions/checkout@v4 action. This step retrieves the latest version of the codebase from the repository, ensuring that the tests are run against the most up-to-date code. Next, the job uses the actions/cache@v3 action to cache the Library folder. The Library folder contains the project's imported assets and other cached data, which can significantly speed up the test execution time. The cache is keyed using a hash of the **/Packages/packages-lock.json file, ensuring that the cache is invalidated whenever the project's dependencies change. This step also includes a restore-keys section that specifies fallback keys to use if the primary key does not match, allowing the job to restore a previous cache if available. After caching the Library folder, the job runs the EditMode tests using the game-ci/unity-test-runner@v4 action. This action is specifically designed for running Unity tests in a CI environment. The testMode parameter is set to editmode, indicating that only EditMode tests should be run. The artifactsPath parameter specifies the directory where test results and logs should be stored. The customParameters parameter allows you to pass additional command-line arguments to the Unity editor, such as the -logfile and -stackTraceLogType options, which control the output of logs and stack traces. Finally, the job uploads the test results and logs as artifacts using the actions/upload-artifact@v4 action. This ensures that the test results are available for analysis and can be easily accessed from the GitHub Actions interface.

PlayMode Job

The playmode job is configured to run tests that require a built player, simulating the runtime environment of the game. This job is essential for verifying gameplay mechanics, user interactions, and other runtime behaviors. Similar to the editmode job, the playmode job includes several steps to ensure efficient test execution and result capture. The job starts by checking out the code using the actions/checkout@v4 action, ensuring that the latest version of the codebase is used. Next, the actions/cache@v3 action is used to cache the Library folder, which helps to speed up the test execution time. The cache is keyed using a hash of the **/Packages/packages-lock.json file, and fallback keys are specified to restore a previous cache if available. The core of the playmode job is the game-ci/unity-test-runner@v4 action, which runs the PlayMode tests. The testMode parameter is set to playmode, indicating that only PlayMode tests should be executed. The artifactsPath parameter specifies the directory for storing test results and logs, and the customParameters parameter allows passing additional command-line arguments to the Unity editor. The UNITY_LICENSE environment variable is set using a secret, ensuring that the Unity editor is properly licensed for running tests in a CI environment. Finally, the job uploads the test results and logs as artifacts using the actions/upload-artifact@v4 action, making them available for analysis and review. By running the editmode and playmode jobs in parallel, the workflow significantly reduces the overall testing time, providing faster feedback to developers and improving the efficiency of the development process.

Key Configuration Elements

Let's highlight some key configuration elements within the YAML file that are crucial for understanding how the parallel testing workflow operates. These elements include the use of caching, custom parameters, and environment variables, each playing a vital role in optimizing the testing process.

The use of caching is a critical aspect of the workflow, significantly reducing the time it takes to run tests. The actions/cache@v3 action is used in both the editmode and playmode jobs to cache the Library folder. The Library folder contains the project's imported assets and other cached data, which can take a considerable amount of time to generate. By caching this folder, subsequent test runs can reuse the cached data, avoiding the need to reimport assets and regenerate cached data. This can result in a substantial reduction in test execution time, especially for large projects with many assets. The cache is keyed using a hash of the **/Packages/packages-lock.json file, ensuring that the cache is invalidated whenever the project's dependencies change. This prevents the use of outdated cached data, which could lead to test failures or incorrect results. Fallback keys are also specified, allowing the workflow to restore a previous cache if the primary key does not match. This provides an additional layer of resilience, ensuring that the cache is used effectively even if the project's dependencies have changed slightly.

Custom parameters are another important aspect of the configuration, allowing you to fine-tune the behavior of the Unity test runner. The customParameters field in the game-ci/unity-test-runner@v4 action allows you to pass additional command-line arguments to the Unity editor. In this workflow, the -logfile and -stackTraceLogType options are used to control the output of logs and stack traces. The -logfile option specifies the path to the log file, while the -stackTraceLogType option controls the level of detail included in stack traces. By setting these parameters, you can customize the logging behavior of the Unity editor, making it easier to diagnose test failures and identify issues. For example, setting -stackTraceLogType Full ensures that full stack traces are included in the logs, which can be invaluable for debugging complex issues. The use of custom parameters allows you to tailor the test execution environment to your specific needs, ensuring that you have the information you need to effectively troubleshoot test failures.

Environment variables play a crucial role in configuring the test environment, particularly for licensing and security. The UNITY_LICENSE environment variable is used to provide the Unity editor with a valid license for running tests in a CI environment. This variable is set using a secret, ensuring that the license key is not exposed in the workflow configuration. Unity requires a valid license to run in headless mode, which is the typical mode of operation in a CI environment. By providing the license key as an environment variable, the workflow can ensure that the Unity editor is properly licensed, allowing tests to be run without interruption. The use of secrets is essential for protecting sensitive information, such as license keys, API keys, and other credentials. GitHub Actions provides a secure way to store and use secrets in workflows, ensuring that they are not exposed in the workflow configuration or logs. By using environment variables and secrets, the workflow can create a secure and properly configured test environment, ensuring that tests are run reliably and securely.

Integrating Parallel Testing into Your Project

So, how can you integrate this parallel testing workflow into your Unity project? The process is straightforward, and by following these steps, you can significantly improve your testing efficiency. Let's walk through the necessary steps to get this up and running in your project.

First, you'll need to add the unity-tests-parallel.yml file to your project's .github/workflows directory. This directory is where GitHub Actions workflows are stored. If the directory doesn't exist, you'll need to create it. You can simply copy the content from the provided diff into a new file named unity-tests-parallel.yml within your project's repository. Make sure to commit and push this file to your repository so that GitHub Actions can recognize and execute the workflow. Once the file is in place, GitHub Actions will automatically detect it and start running the workflow based on the triggers defined in the file. This initial step is crucial for enabling parallel testing in your project, as it sets up the foundation for running EditMode and PlayMode tests concurrently.

Next, you need to configure the UNITY_LICENSE secret in your GitHub repository. This secret is used to provide the Unity editor with a valid license for running tests in a CI environment. To configure this secret, navigate to your repository on GitHub, go to the "Settings" tab, and then click on "Secrets" in the left sidebar. Click the "New repository secret" button and create a secret named UNITY_LICENSE. The value of this secret should be your Unity license key. Ensure that you have a valid Unity license that allows for automated testing in a CI environment. This step is essential for ensuring that your tests can run without interruption and that you comply with Unity's licensing terms. Without a valid license, the Unity editor will not be able to run in headless mode, which is required for automated testing in a CI environment.

Finally, with the unity-tests-parallel.yml file in place and the UNITY_LICENSE secret configured, the parallel tests will automatically run on each push to the main branch and on each pull request. You can monitor the progress and results of the tests in the "Actions" tab of your GitHub repository. This tab provides a detailed view of all workflow runs, including the status of each job and step. You can click on a specific workflow run to see the logs and artifacts generated by the tests. If any tests fail, you can examine the logs to identify the cause of the failure and take corrective action. This automated testing process ensures that your code is continuously tested, providing you with early feedback on any issues and helping you maintain a high level of code quality. By integrating parallel testing into your project, you can significantly reduce the time spent on testing, allowing you to iterate more quickly and deliver more stable releases.

Benefits of Parallel Testing

Implementing parallel testing offers numerous benefits that can significantly improve your development workflow. From reduced testing time to faster feedback loops, the advantages are compelling. Let’s explore some of the key benefits of adopting parallel testing in your Unity projects.

One of the most significant benefits of parallel testing is the substantial reduction in testing time. By running tests concurrently, you can drastically decrease the overall time spent on testing, especially for large projects with extensive test suites. Traditional sequential testing methods require waiting for one set of tests to complete before starting another, which can be a major bottleneck. With parallel testing, EditMode and PlayMode tests, for example, can run simultaneously, cutting the total testing time down to the duration of the longest test suite rather than the sum of all test suite durations. This time savings translates to faster feedback loops, allowing developers to identify and fix issues more quickly. Reduced testing time also means that you can run tests more frequently, ensuring that your code is continuously tested and that any regressions are caught early in the development process. This can lead to more stable releases and a higher level of code quality.

Faster feedback loops are another crucial advantage of parallel testing. When tests are run in parallel, developers receive feedback on their code changes much more quickly. This allows them to identify and fix issues sooner, reducing the time it takes to resolve bugs and iterate on new features. With traditional sequential testing, developers may have to wait for hours or even days to receive feedback on their code changes, especially for large projects with long test execution times. This delay can disrupt the development process and make it more difficult to maintain a high level of code quality. Parallel testing, on the other hand, provides near-instant feedback, allowing developers to address issues while they are still fresh in their minds. This faster feedback loop can significantly improve developer productivity and reduce the risk of introducing regressions into the codebase.

Improved developer productivity is a direct result of the reduced testing time and faster feedback loops offered by parallel testing. When developers spend less time waiting for tests to complete, they have more time to focus on writing code and building new features. The faster feedback loops also allow them to iterate more quickly, making it easier to experiment with new ideas and find optimal solutions. This increased productivity can lead to faster release cycles and a more competitive product. Additionally, parallel testing can reduce the frustration associated with long test execution times, making the development process more enjoyable and less stressful. By providing a more efficient and streamlined testing process, parallel testing can help developers be more productive, creative, and effective in their work.

Conclusion

Enabling parallel testing in your Unity projects can significantly boost your development efficiency. By running EditMode and PlayMode tests concurrently, you can reduce testing time, accelerate feedback loops, and enhance developer productivity. The unity-tests-parallel.yml workflow file provides a straightforward way to integrate parallel testing into your CI pipeline using GitHub Actions. So, go ahead and implement this patch to streamline your testing process and deliver higher-quality games faster. Happy testing, guys!