public void assertFiltersMutationsFromMutator(String id, Class<?> clazz) { final Sample s = sampleForClass(clazz); final GregorMutater mutator = mutateFromClassLoader(); final List<MutationDetails> mutations = mutator.findMutations(s.className); final Collection<MutationDetails> actual = filter(s.clazz, mutations, mutator); final SoftAssertions softly = new SoftAssertions(); checkHasNMutants(1, s, softly, mutations); final List<MutationDetails> filteredOut = FCollection.filter(mutations, notIn(actual)); softly.assertThat(filteredOut).describedAs("No mutants filtered").isNotEmpty(); softly.assertThat(filteredOut).have(mutatedBy(id)); softly.assertAll(); }