EasyMock test an exception is thrown in the middle of code

Question

I am writing test using EasyMock and there is a piece of source code like this:

public void doSomething(){
    try
    {
        // Do something
    }
    catch (RejectedExecutionException ex)
    {
        // just add some metrics here, no big action
    }
}

i am writing test for the case throwing RejectedExecutionException, but exception is not thrown finally, which means i can't use ExpectedException. So how should i test this exception is thrown once with EasyMock?

Answer 1

I do not think that you have a clean way to do this with any mockup framework. I however can suggest you the following solutions.

Solution 1

Modify you code of doSomething() as following:

public void doSomething(){
    try
    {
        doSomethingImpl(); // throws RejectedExecutionException
    }
    catch (RejectedExecutionException ex)
    {
        // just add some metrics here, no big action
    }
}. 

Now implement test for both doSomethingImpl() that should throw exception and doSomething() that should not with the same input data and state.

Solution 2

You catch code does something, doesn't it? For example calls log.error(). You can verify that specific call indeed happened and happened only once. I do not remember the specific syntax to do this with EasyMock, but with Mockito it is very simple: use Mockito.verify().

Solution 3 You can use PowerMock to check that constructor of you exception was called. It is not very clean because theoretically you can create instance of exception but do not throw it, but it is better than nothing.

Probably you can even combine these solutions. However I believe that the first is the best one.

Answer 2

The Do something part calls a mock throwing the exception?

If yes, just do expect(mock.methodCalled()).andThrow(new RejectedExecutionException());

And then EasyMock.verify(mock) at the end of your test. This will make sure methodCalled was called once and only once.