title: How to mock only one method using Sinon?
body: <p>I've got a single method in my namespace that I'd like to <a href="http://sinonjs.org/docs/#mocks" rel="nofollow">mock</a>, but I'd prefer that all the others work normally.  Is it possible to have sinon mock a specific method while leaving the others the same?</p>
  
  <p>My understanding is I'm not looking for a spy because I want to assert that the mock was called with specific parameters.  </p>
  
  <p>Here's my code in CoffeeScript:</p>
  
  <pre><code>root.targeting.handleUnitsAttack = (gameState) -&gt;
    units = gameState.heroes.concat(gameState.badGuys)
    for source in units
      for target in units
        gameState = root.targeting.sourceAttackTarget(gameState, source, target)
    gameState
  </code></pre>
  
  <p>I'd like to mock <code>sourceAttackTarget</code> and verify that its arguments are specific values.  </p>