Mockito when/then not working
<p>I'm trying to Mock <code>ValidatorService</code> in unit tests of <code>SubscriptionInterceptor</code>.</p>

<pre><code>validator = Mockito.mock(ValidatorService.class);
Mockito.when(validator.validateSubscription(any(), any(), any())).thenReturn("");
interceptor = new SubscriptionInterceptor(validator);
</code></pre>

<p>Later, when the interceptor calls the <code>validateSubscription</code> method of the mocked validator, an instance of the actual class is invoked, rather than the mock. Why? How can I get the method call to return an empty String?</p>