JUnit 5: Assert an exception is thrown fails with an error - unit-testing

Question

I am working on writing unit test cases for my DAO using the Junit5. I want to test whether the BadRequestException is thrown when maximum template reached and check whether NotFoundException is thrown when template is not found. But I am getting the following exception:
org.mockito.exceptions.misusing.InvalidUseOfMatchersException: You cannot use argument matchers outside of verification or stubbing.
My code:
TemplateDao.java:
#Transactional(readOnly = true)
public MyTemplateDetailsView getTemplateDetails(Long templateId) {
Session session = sessionFactory.getCurrentSession();
MyTemplate myTemplate = getTemplate(templateId);
if (null == myTemplate || myTemplate.getStatus() != TemplateStatus.ACTIVE.value) {
throw new NotFoundException("template.not.found");
}
Integer templatesCount = getTempletsCount(templateId);
if (templatesCount > templateLimit) {
LOGGER.info("max template count reacged");
throw new BadRequestException("template.limit.exceded");
}
}
TemplateDaoTest.java:
#Test
void getTemplateDetails_ThrowsNotFoundException_IfTemplateNotinActiveStatus() {
Assertions.assertThrows(NotFoundException.class, () -> {
when(templateDao.getTemplate(anyLong())).thenReturn(null);
});
}
#Test
public void getTemplateDetails_ThrowsBadRequestException_IfTemplateLimitExceeded() {
Integer limit = 100;
assertThrows(BadRequestException.class, () -> {
when(templateDao.getTempletsCount(anyLong())).thenReturn(limit);
templateDao.getTemplateDetails(anyLong);
});
}

Answer 1

I suspect the problem is in the following block of code:
assertThrows(BadRequestException.class, () -> {
when(templateDao.getTempletsCount(anyLong())).thenReturn(limit);
templateDao.getTemplateDetails(anyLong);
});
I'm not sure where the anyLong comes from, so I'll make an assumption that you meant anyLong(), as in org.mockito.ArgumentMatchers.anyLong.
If so, the problem with this is that you're trying to use a Matcher instead of a concrete value outside of stubbing context (i.e. outside of the specification of what method should return when called).
You need to pass in a proper Long, i.e. 150L (or whatever is larger than templateLimit) when you're calling your stubbed method. For example:
assertThrows(BadRequestException.class, () -> {
when(templateDao.getTempletsCount(anyLong())).thenReturn(limit);
templateDao.getTemplateDetails(150L); // note the concrete value
});
It's actually fairly trivial to reproduce if you're inclined to do so (I'm using JUnit 4, but it should be okay with JUnit 5, too):
public class MatchersTest {
#Test
public void testConversion() {
Converter converter = new Converter();
when(converter.from(anyLong())).thenReturn("1");
converter.from(anyLong());
}
private static class Converter {
String from(Long number) {
return String.valueOf(number);
}
}
}