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Practice: Migrate to JUnit 5

Ready to practice migrating from JUnit 4 to JUnit 5? We've prepared a test class with common JUnit 4 patterns that you can improve.

Exercise: OrderValidatorTest​

The OrderValidatorTest class in the orders module demonstrates several JUnit 4 patterns that need migration:

What you'll find​

  • ❌ JUnit 4 annotations: @Before, @Test from org.junit.
  • ❌ Try-catch-fail pattern: Awkward exception testing with try-catch blocks.
  • ❌ Verbose assertions: Manual loops and checks.
  • ❌ Old assertion style: JUnit 4's assertTrue, assertEquals, assertFalse.

Your task​

Migrate this test to JUnit 5 and improve the test patterns.

Hints:

  • Look at the Migrate to JUnit 5 page for guidance on package and annotation changes.
  • JUnit 5 uses different package names (org.junit.jupiter.api.* instead of org.junit.*).
  • Lifecycle annotations have new names that better express their purpose.
  • Exception testing can be done more elegantly without try-catch blocks.
  • JUnit 5 relaxes visibility requirements for test classes and methods.

Running the test​

You can run the test in your IDE or use the following commands:

# Run the test
mvn test -pl orders -Dtest=OrderValidatorTest

# Or run all tests in the orders module
mvn test -pl orders

Automated migration​

You can also use OpenRewrite to automatically migrate the test:

mvn -U org.openrewrite.maven:rewrite-maven-plugin:run \
  -Drewrite.recipeArtifactCoordinates=org.openrewrite.recipe:rewrite-testing-frameworks:RELEASE \
  -Drewrite.activeRecipes=org.openrewrite.java.testing.junit5.JUnit4to5Migration

See the Migrate to JUnit 5 page for more migration options.

What you'll learn​

By completing this exercise, you'll gain hands-on experience with:

  • Converting JUnit 4 lifecycle annotations to JUnit 5.
  • Modernizing exception testing patterns.
  • Improving test readability and maintainability.
  • Understanding the benefits of JUnit 5 over JUnit 4.