What’s New in JUnit 5.3

Billy Korando
Sep 10, 2018 · 4 min read
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“rocket ship photography” by SpaceX on Unsplash

The JUnit team continues to make steady work refining and improving on JUnit 5. In this article we will take a look at some of the new features and changes that are in JUnit 5.3 which was released on September 3rd. Also in this article we will look at some recent changes and improvements to libraries and tools that are often used in conjunction with JUnit.

Parallel Test Execution

  • Parallel test execution is enabled and configured through the build file (i.e. pom.xml, build.gradle)
  • Parallel test execution behavior can be modified at the method and class level with the annotations: @Execution and @ResourceLock.

Be sure to check out the user guide for more detailed information on configuring and using parallel test execution in JUnit 5.

AssertThrows Enhancements

T̶h̶e̶ ̶a̶s̶s̶e̶r̶t̶T̶h̶r̶o̶w̶s̶ ̶a̶s̶s̶e̶r̶t̶i̶o̶n̶ ̶h̶a̶s̶ ̶b̶e̶e̶n̶ ̶u̶p̶d̶a̶t̶e̶d̶ ̶t̶o̶ ̶d̶i̶s̶p̶l̶a̶y̶ ̶t̶h̶e̶ ̶v̶a̶l̶u̶e̶ ̶r̶e̶t̶u̶r̶n̶e̶d̶ ̶f̶r̶o̶m̶ ̶a̶ ̶m̶e̶t̶h̶o̶d̶,̶ ̶i̶f̶ ̶a̶n̶y̶,̶ ̶w̶h̶e̶n̶ ̶a̶n̶ ̶e̶x̶c̶e̶p̶t̶i̶o̶n̶ ̶i̶s̶ ̶n̶o̶t̶ ̶t̶h̶r̶o̶w̶n̶.̶ ̶T̶h̶i̶s̶ ̶c̶a̶n̶ ̶b̶e̶ ̶h̶e̶l̶p̶f̶u̶l̶ ̶w̶h̶e̶n̶ ̶d̶e̶b̶u̶g̶g̶i̶n̶g̶ ̶a̶ ̶t̶e̶s̶t̶ ̶c̶a̶s̶e̶ ̶t̶h̶a̶t̶ ̶h̶a̶s̶ ̶s̶t̶a̶r̶t̶e̶d̶ ̶f̶a̶i̶l̶i̶n̶g̶.̶ ̶H̶e̶r̶e̶ ̶i̶s̶ ̶a̶ ̶s̶c̶r̶e̶e̶n̶s̶h̶o̶t̶ ̶o̶f̶ ̶w̶h̶a̶t̶ ̶t̶h̶i̶s̶ ̶d̶i̶s̶p̶l̶a̶y̶ ̶l̶o̶o̶k̶s̶ ̶l̶i̶k̶e̶ ̶i̶n̶ ̶E̶c̶l̶i̶p̶s̶e̶.̶ ̶I̶n̶ ̶t̶h̶i̶s̶ ̶e̶x̶a̶m̶p̶l̶e̶ ̶a̶n̶ ̶e̶m̶p̶t̶y̶ ̶L̶i̶s̶t̶ ̶i̶s̶ ̶b̶e̶i̶n̶g̶ ̶r̶e̶t̶u̶r̶n̶e̶d̶ ̶i̶n̶s̶t̶e̶a̶d̶ ̶o̶f̶ ̶t̶h̶e̶ ̶e̶x̶p̶e̶c̶t̶e̶d̶ ̶e̶x̶c̶e̶p̶t̶i̶o̶n̶.

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Capturing Console Output

To start capturing console output it requires two steps:

1. Implementing a TestExecutionListener

2. Configuring surefire to start capturing console output.

Here is an example of each:


Surefire Configuration

Library and Tool Updates

Surefire Native Support

With 2.22.0 the default surefire configuration can look like this:

Note: For spring boot projects, you need only add maven-surefire-plugin.version to your properties, like this.

Note 2: JUnit 5.3 has a bug that prevents tests from being found when the reuseForks tag is set to false. Read more here.

Filtering Changes with Native Support

However this does not work when running maven-surefire-plugin 2.22.0. To pass to surefire which tags you want to filter on you must use the groups, for which tests to execute, and excludeGroups, for which tests should not be executed, tags. Here is the 2.22.0 equivalent example of the above:

Enhanced Mockito Dependency Injection Support

As the tweet from @sam_brannen states, you can now directly inject mockito mocks via constructor or method parameters. This can make help make tests more declarative as to what they depend upon and/or a little cleaner. These changes were added in 2.21.0¹, here is an example of those changes in action:

AssertJ Soft Assertions and opentest4J

I have covered AssertJ in a previous blog post. With 3.11.1 AssertJ will now use the MultipleFailuresError in the opentest4j library, if it’s available. opentest4j is a library created by the JUnit 5 team to help make the testing experience more consistent across projects for both users and library developers.

If you are not familiar with soft assertions, they are a way of asserting multiple values in a single test and instead of the test failing on the first assertion, all the failed assertions are instead collected and reported at the end of the test. This can help avoid the irritating loop of a test failing, fixing the failure, running the test again, and hitting another failure. Here’s a look at soft assertions in AssertJ:

Running this test will return both assertion failures, instead of just reporting that the first assert failed.

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1: Technically the changes were added in 2.20.3, but that is only available from the mockito’s maven repository, not maven central.

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