Скачать или смотреть Understanding ParameterizedTest in JUnit 5: A Guide for Smooth Migration from JUnit 4

Discover how to successfully implement `ParameterizedTest` in JUnit 5, including useful examples and tips for migration from JUnit 4.
---
This video is based on the question https://stackoverflow.com/q/70822487/ asked by the user 'flowAlong' ( https://stackoverflow.com/u/15543279/ ) and on the answer https://stackoverflow.com/a/70823092/ provided by the user 'Bastis Programming Corner' ( https://stackoverflow.com/u/4345417/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: ParametrizedTest with displayName and Argument

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding ParameterizedTest in JUnit 5: A Guide for Smooth Migration from JUnit 4

Migrating from JUnit 4 to JUnit 5 can be a challenging task, especially when it comes to using ParameterizedTest. If you’ve encountered problems while trying to set up your tests with different display names and arguments, you’re not alone. In this guide, we will explore the common issue of parameter resolution in JUnit 5, and we’ll walk through how to properly set up your test data and function to avoid any confusion.

The Problem: Parameter Resolution Exception

In your scenario, you’re trying to implement a parameterized test that uses a custom display name and an argument of type MyClass. However, you’re facing a ParameterResolutionException that states:

[[See Video to Reveal this Text or Code Snippet]]

This indicates that JUnit 5 is unable to unbox the provided argument for the test. The reason this failure occurs is likely due to the way you are supplying your test data.

Solution: Utilizing Stream<Arguments>

In JUnit 5, instead of returning a Collection<Object[]> from your data source, you should return a Stream<Arguments>. This allows you to pass multiple parameters in an organized manner. Let’s break down the solution into clear steps.

Step 1: Modifying the Data Source

Change your data method to return a Stream<Arguments> rather than a Collection<Object[]>. Within this method, you can use the Arguments.arguments() utility to wrap your test data.

Here’s an example:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Updating the Test Method

Now, you need to ensure that your test method’s signature matches the parameters you’re providing in the arguments:

[[See Video to Reveal this Text or Code Snippet]]

The Final Code Example

Putting it all together, here’s how your complete parameterized test class might look:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Transitioning from JUnit 4 to JUnit 5 may seem daunting, especially when implementing parameterized tests. However, by leveraging Stream<Arguments> instead of the old Collection<Object[]>, you not only resolve issues like parameter resolution exceptions but also enhance the readability and maintainability of your tests.

If you keep these principles in mind, your tests will be much easier to manage and execute as you adopt JUnit 5. Happy testing!