On Thu, 19 Feb 2026 08:33:10 GMT, Volkan Yazici <[email protected]> wrote:
>> When using >> [TestInstance.Lifecycle.PER_CLASS](https://docs.junit.org/5.0.0/api/org/junit/jupiter/api/TestInstance.html) >> then a single instance of the class will be used to invoke all test >> methods. It makes it possible to use `@BeforeAll` `@AfterAll` to setup and >> teardown objects/variables that all tests methods depend on. Typically in >> the `HttpClient` tests we use that to start, and then stop, the `HttpServer` >> instances that all test methods will interact with. AFAIU that was the >> default with TestNG - but the JUnit default is to create one instance of the >> test class for each test method invocation. Using >> `TestInstance.Lifecycle.PER_CLASS` makes it easier to migrate from TestNG to >> JUnit. > >> When using >> [TestInstance.Lifecycle.PER_CLASS](https://docs.junit.org/5.0.0/api/org/junit/jupiter/api/TestInstance.html) >> then a single instance of the class will be used to invoke all test >> methods. It makes it possible to use `@BeforeAll` `@AfterAll` to setup and >> teardown objects/variables that all tests methods depend on. > > @dfuch, AFAICT, as long as your shared state is in `static` variables, > `@BeforeAll`/`@AfterAll` will be executed _once_ even if test methods use > different instances. Consider the following example: > > /* @test > * @run junit ${test.main.class} */ > > import org.junit.jupiter.api.BeforeAll; > import org.junit.jupiter.api.Test; > > class FooTest { > private static int X; > @BeforeAll static void beforeAll() { System.err.println("beforeAll"); > X = 1; } > FooTest() { System.err.println("ctor"); } > @Test void test1() { System.err.println("test1's X:" + X); } > @Test void test2() { System.err.println("test2's X:" + X); } > } > > `make run-test TEST=/path/to/FooTest.java` will produce the following JTReg > output: > > beforeAll > ctor > [09:24:27.225] STARTED FooTest::test1 'test1()' > test1's X:1 > [09:24:27.233] SUCCESSFUL FooTest::test1 'test1()' [8ms] > ctor > [09:24:27.234] STARTED FooTest::test2 'test2()' > test2's X:1 > [09:24:27.235] SUCCESSFUL FooTest::test2 'test2()' [0ms] > > Above test output indicates that > > 1. `beforeAll()` is executed once > 2. Both `test1` and `test2` observe the same `X` > > In conclusion, I think we can do without any `@TestInstance`. If you think > otherwise, would you mind helping me to understand, please? As it happens most of the tests I converted have shared instance variables that are set up and teared down by non-static methods annotated with `@BeforeAll` and `@AfterAll`. And `LifeCycle.PER_CLASS` helps preserving the previous (testNG) behavior. I don't see a need to change that - or to remove that annotation. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/29786#discussion_r2826513725
