Migrating from TestNG to JUnit Jupiter

• Test classes should be annotated with @TestInstance(Lifecycle.PER_CLASS) to align with TestNG semantics.
• @BeforeClass/@AfterClass methods should be annotated with @BeforeAll/@AfterAll.
• Tests using data providers should be converted to parameterized tests (@ParameterizedTest).
• The order of the expected and actual arguments to assertion methods such as assertEquals(...) needs to be swapped so that the expected result precedes the actual result.
• Usage of expectThrows(...) should be changed to assertThrows(...).
• Tests that threw SkipException should make use of the the Assumptions API.

Automated Migration Support

• MBoegers/migrate-testngtojupiter-rewrite
• Philzen/rewrite-recipe-testng-to-junit-jupiter

Example Migrations

• OpenJDK (https://github.com/openjdk/jdk)
  • Convert virtual thread tests to JUnit
  • Use JUnit in lib-test/jdk tests