title: Using JMockit to mock autowired interface implementations
body: <p>We are writing JUnit tests for a class that uses Spring autowiring to inject a dependency which is some instance of an interface. Since the class under test never explicitly instantiates the dependency or has it passed in a constructor, it appears that JMockit doesn't feel obligated to instantiate it either.</p>
  
  <p>Up until now we have been using SpringRunner to have Spring load mock dependencies for us, which works. Two things we don't like about this are 1) the Spring framework has to be loaded and initialized each time running the tests which is not exactly speedy, and 2) we are forced to explicitly create all mock dependencies as real classes, something which JMockit helps eliminate. </p>
  
  <p>Here's a simplified example of what we're testing:</p>
  
  <pre><code>public class UnitUnderTest {
  
     @Autowired
     ISomeInterface someInterface;
  
     public void callInterfaceMethod() {
  
        System.out.println( "UnitUnderTest.callInterfaceMethod calling someInterface.doSomething");
        someInterface.doSomething();
     }
  
  }
  </code></pre>
  
  <p>So, the question is, is there a way to have JMockit create a mock <code>someInterface</code>?</p>