Parallel Test Execution for JUnit 5

How to Implement Parallel Test Execution for JUnit 5

In JUnit 5, the parallel execution of tests is supported natively. This allows you to improve the execution speed of your tests, saving valuable time and resources. In this article, we'll take a look at how to set up and execute tests in parallel using JUnit 5.

Requirements for Parallel Execution

Before you can start to run tests in parallel, there are a few requirements that must be met:

• You must be using the JUnit 5 library.
• You must have two or more tests that can be executed in parallel.
• You must set up the parallel execution configuration.

Setting Up Parallel Execution

Once you have the necessary requirements in place, you can start setting up parallel execution. To do this, you need to first add the following dependencies to your project's build file (for example, Maven or Gradle):

<dependency>
  <groupId>org.junit.vintage</groupId>
  <artifactId>junit-vintage-engine</artifactId>
  <version>5.6.2</version>
  <scope>test</scope>
</dependency>
<dependency>
  <groupId>org.junit.jupiter</groupId>
  <artifactId>junit-jupiter-engine</artifactId>
  <version>5.6.2</version>
  <scope>test</scope>
</dependency>

Now, you can configure parallel execution in your project’s test execution environment. You will need to specify the following parameters:

• parallelMode - This parameter defines how the tests will be executed. The available options are classes and methods.
• threadPoolSize - This parameter defines the number of threads that will be used for parallel execution.
• perCoreThreadCount - This parameter determines the number of threads that will be allocated to each processor core.
• useUnlimitedThreads - This parameter dictates whether an unlimited number of threads should be used.

Executing Tests in Parallel

Once your parallel execution is set up, you can execute tests in parallel by invoking the test runner with the appropriate command line arguments. For example, on a Linux or OS X system, you can use the following command line:

java -jar /path/to/your/test-runner.jar --parallel-mode=classes --thread-count=4

This will execute all of your tests in parallel, using four threads. You can also specify additional parameters, such as perCoreThreadCount if you wish to limit the number of threads that will be used by each processor core.

Conclusion

Parallel test execution is a powerful tool for improving the speed of your unit tests. With JUnit 5, it's easy to set up and execute tests in parallel. We hope this article has helped you understand how to get started with parallel test execution for JUnit 5.