Migrating from TestNG to JUnit Jupiter

Migrating from TestNG to JUnit Jupiter

Quick Notes

• 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).
• Use @ParameterizedTest(autoCloseArguments=false) when types of the arguments implement AutoCloseable and JUnit should not close them.
• 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

• lahodaj/netbeans/.../junit-convert

• MBoegers/migrate-testngtojupiter-rewrite

• Philzen/rewrite-recipe-testng-to-junit-jupiter

Fixes for Errors and Failures

You should apply following fixes when you encounter the error shown below.

Make argument source factory method static

Method 'public java.lang.Object[][] org.openjdk.tests.javac.FDTest.caseGenerator()'
  must be static: local factory methods must be static
  unless the PER_CLASS @testinstance lifecycle mode is used;
  external factory methods must always be static.

Make @AfterAll-annotated method static

[ERROR] @afterall method 'public void org.openjdk.tests.vm.FDSeparateCompilationTest.cleanupCompilerCache()'
  must be static unless the test class
  is annotated with `@TestInstance(Lifecycle.PER_CLASS)`.

Remove static modifier from @Test-annotated methods

This configuration error should have been detected by JUnit Jupiter and reported via the Discovery Issues API: https://docs.junit.org/current/user-guide/#running-tests-discovery-issues

Add Custom TestInstanceFactory

Class [FDTests] must declare a single constructor
Class [MethodReferenceTestKinds] must declare a single constructor

Example Migrations

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