title: Moq testing void method
body: <p>Hi I am new to Moq testing and having hard time to do a simple assertion. 
  I am using an interface </p>
  
  <pre><code> public interface IAdd
   {
       void add(int a, int b);
   }
  </code></pre>
  
  <p>Moq for the <code>IAdd</code> interface is:</p>
  
  <pre><code>  Mock&lt;IAdd&gt; mockadd = new Mock&lt;IAdd&gt;();
    mockadd.Setup(x =&gt; x.add(It.IsAny&lt;int&gt;(), It.IsAny&lt;int&gt;()).callback((int a, int b) =&gt; { a+b;});
    IAdd testing = mockadd.Object;
  </code></pre>
  
  <p>Since the <code>add</code> method is void, it doesn't return any value to Assert with. How can I assert this setup?</p>