How to mock LocalDate time inside an @Async method while writing unit tests?

Question

I need to mock LocalDateTime inside an @Async method. But mocked localdatetime does not work inside Async method.But removing async works as expected.I have attached the code so far.

public interface ConfigurationProcessor<T> {
    void process(Configuration configuration);
}

Here is the implementation of above interface

    @Service
    public class ConfigurationProcessoeStudents10Impl implements ConfigurationProcessor<Student> {
        
        private final StudentRepository studentRepository;
    
        @Autowired
        public ConfigurationProcessoeStudents10Impl(StudentRepository studentRepository) {
            this.studentRepository = studentRepository;
            }
        
        @Override
        @Async
        public void process(Configuration configuration) {
            studentRepository.save(Student.builder().Name(configuration.name).Age(configuration.age).RegTime(LocalDateTime.now).build());
        }

}    

This is the unit test

@EnableAutoConfiguration
@SpringBootTest
public class StudentsC10IT {

  @Autowired
  ConfigurationProcessor<StudentC10> configurationProcessor;
  
  @Test
  @Tag("VerifyProcess")
  @DisplayName("Verify kafka event consumer from configuration manager")
  void verifyProcess(){
   LocalDateTime lt = LocalDateTime.parse("2018-12-30T19:34:50.63");
    try (MockedStatic<LocalDateTime> localDateTimeMockedFourMonth = Mockito
            .mockStatic(LocalDateTime.class, Mockito.CALLS_REAL_METHODS)) {
      localDateTimeMockedFourMonth.when(LocalDateTime::now).thenReturn(lt));
      configurationProcessor.process();
    }
  }

}

Need to know how to mock LocalDateTime inside this @Async method without using power mockito ?

Answer 1

MockedStatic is thread-local thing, as stated in Mockito docs. Also you should call close() for this object.

And @Async do execution of method in different thread, and this is why your test is not working.

As possible solution for your test - disable async: see answers here