How to replace WireMock @Rule annotation in JUnit 5?

In a general way, what you did with @Rule and @ClassRule in JUnit 4 should be done with @ExtendWith and Extension that associated provide a very close feature in JUnit 5.
It works as standards JUnit lifecycle hooks but that it is extracted in a Extension class. And similarly to @Rule, as many Extensions as required may be added for a test class.

To handle the issue you have several possible approaches among :

• keep the JUnit 4 way (JUnit 5 owns the JUnit Vintage part that allows to execute JUnit 3 or 4 tests).
• rewrite the @Rule as an Extension.
• do the actual processing done by WireMockRule (start the server, execute your tests and stop the server) in each test of class with @BeforeEach and @AfterEach hook methods.
• use a third library that implements the equivalent of WireMockRule in the JUnit 5 Extension way such as https://github.com/lanwen/wiremock-junit5

Note that your issue already discussed in the JUnit 5 Issues.