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Learn how to effectively use `@ EnabledIfSystemProperty` with `@ ParameterizedTest` in JUnit 5 to conditionally execute your tests based on system properties.
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How to Conditionally Run Parameterized Tests in JUnit 5

When writing tests in JUnit 5, you may encounter situations where you need to execute certain tests only under specific conditions. This is especially true for parameterized tests, where you may want the tests to run only if a particular system property is set. In this post, we’ll explore how to achieve that using the @ EnabledIfSystemProperty annotation along with the @ ParameterizedTest annotation.

The Problem: Conditional Execution with Parameterized Tests

Let's say you’re using JUnit 5 for testing and want to execute a parameterized test only when the environment variable env is set to test. First, you might try something like this:

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

However, the issue arises because while the test might appear as "green" in the results, it does not execute when the condition is false. In IntelliJ IDEA, this can be confusing since you expect to see the test grayed out like it would be with a regular test annotated with @ Test. Instead, the lack of execution is not visibly indicated, leading to ambiguity in test results.

The Solution: Using Nested Tests

One of the most effective ways to solve this problem is by utilizing JUnit 5’s built-in support for nested tests. By moving the parameterized test into a nested class that is conditionally enabled, only the tests within this nested class will be executed when the condition is met. Here's how to structure your tests:

Step-by-Step Solution

Create a Nested Test Class: Use @ Nested to encapsulate your parameterized tests within a class that can be conditionally enabled.

Apply the Condition: Apply the @ EnabledIfSystemProperty annotation to the nested class itself, rather than to individual tests.

Here's how your code should look:

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

Benefits of This Approach

Clearer Test Results: By using the nested test structure, the entire class will be grayed out in the test results if the condition is not satisfied, providing immediate visibility into which tests are effectively skipped.

Maintainability: This pattern also improves the organization of your tests, keeping related parameterized tests grouped together.

Conclusion

Incorporating conditional test execution into parameterized tests in JUnit 5 can be challenging, primarily due to the way results are displayed in IDEs like IntelliJ IDEA. However, using nested classes with @ EnabledIfSystemProperty is a powerful way to achieve the intended behavior while keeping your test suite organized and clear. Try this approach in your own test cases to see how it enhances clarity and manageability.

With these practices, you can ensure your tests run under the right conditions, simplifying your testing workflow significantly.