Scala 在测试时不会抛出异常

Question

I am not able to simulate throwing an Exception in Scala test. Getting error: Expected exception java.lang.Exception to be thrown, but no exception was thrown

test("test with Exception"){
   val generatorService=mock[GeneratorService]
   val entityProviderRequest=new EntityProviderRequest(entity:Entity)
   when(generatorService.generateVertex(entityProviderRequest.entity, "abc")).thenThrow(new RuntimeException)
   intercept[Exception]{
     generatorService.generateElements(entityProviderRequest, "abc")
   }
}

Answer 1

The method you call inside intercept is not the same as the one you defined above. That's why it doesn't throw an exception. When the behaviour is not defined, the mock object simply returns null . The below test should succeed.

test("test with Exception"){
   val generatorService = mock[GeneratorService]
   val entityProviderRequest = new EntityProviderRequest(entity)
   when(generatorService.generateElements(entityProviderRequest, "abc"))
     .thenThrow(new RuntimeException)

   intercept[Exception]{
     generatorService.generateElements(entityProviderRequest, "abc")
   }
}

---

Update

If you want to use the real implementation of a method, but mock the others, you can achieve it by using when(..).thenCallRealMethod() :

test("test with Exception"){
   val generatorService = mock[GeneratorService]
   val entityProviderRequest = new EntityProviderRequest(entity)

   when(generatorService.generateElements(entityProviderRequest, "abc"))
     .thenCallRealMethod()
   when(generatorService.generateVertex(entityProviderRequest.entity, "abc"))
     .thenThrow(new RuntimeException)


   intercept[Exception]{
     generatorService.generateElements(entityProviderRequest, "abc")
   }
}