Issues trying throw checked exception with mockito

Question

I have the below interface

public interface Interface1 {
    Object Execute(String commandToExecute) throws Exception;
}

which then I 'm trying to mock so I can test the behaviour of the class that will call it:

Interface1 interfaceMocked = mock(Interface1.class);
when(interfaceMocked.Execute(anyString())).thenThrow(new Exception());
Interface2 objectToTest = new ClassOfInterface2(interfaceMocked);
retrievePrintersMetaData.Retrieve();

But the compiler tells me that there is an unhandled exception. The definition of the Retrieve method is:

public List<SomeClass> Retrieve() {
    try {
        interface1Object.Execute("");
    }
    catch (Exception exception) {
        return new ArrayList<SomeClass>();
    }
}

The mockito documentation only shows uses of RuntimeException, and I have not seen anything on similar on StackOverflow. I'm using Java 1.7u25 and mockito 1.9.5

Answer 1

Assuming your test method doesn't declare that it throws Exception, the compiler's absolutely right. This line:

when(interfaceMocked.Execute(anyString())).thenThrow(new Exception());

... calls Execute on an instance of Interface1. That can throw Exception, so you either need to catch it or declare that your method throws it.

I would personally recommend just declaring that the test method throws Exception. Nothing else will care about that declaration, and you really don't want to catch it.

Answer 2

You can use doAnswer method of Mockito to thrown checked exceptions, like this

Mockito.doAnswer(
          invocation -> {
            throw new Exception("It's not bad, it's good");
          })
      .when(interfaceMocked)
      .Execute(org.mockito.ArgumentMatchers.anyString());