### Question:
RedirectIdService { public String generateRedirectId(String authorisationId) { redirectIdHolder.setRedirectId(authorisationId); return authorisationId; }  String generateRedirectId(String authorisationId); @Nullable String getRedirectId();  }### Answer:
@Test void generateRedirectId_shouldReturnAuthorisationId() { String redirectId = redirectIdService.generateRedirectId(AUTHORISATION_ID); assertEquals(AUTHORISATION_ID, redirectId); }
@Test void generateRedirectId_shouldStoreIdInHolder() { redirectIdService.generateRedirectId(AUTHORISATION_ID); verify(redirectIdHolder).setRedirectId(eq(AUTHORISATION_ID)); }