title: Verify calls to dependency in unit test?
body: <p>For this following class I want to write a unit test:</p>
  
  <pre><code>public class SomeClass {
  
      private Dependency dependency;
  
      public SomeClass(Dependency dep){
          this.dependency = dep;
      }
  
      private String processString(String s){
          /*
          edit the string and return
           */
      }
  
      public void doSomething(String arg){
  
          String processed = processString(arg);
  
          dep.doSomethingElse(processed);
      }
  }
  </code></pre>
  
  <p>At first I would stub all the methods <code>SomeClass</code> calls on <code>Dependency</code> in order to test my class in isolation. 
  But the question I couldn't yet find an answer to is :</p>
  
  <p>Should I check <em>how</em> <code>SomeClass</code> calls methods of <code>Dependency</code> e.g. what parameters are passed etc. ? 
  Of course this is a pretty trivial example, but I want to know if this should be part of a unit test in general.</p>
  
  <p>Edit: In my case <code>Dependency</code> would be third party api library which I dont control. So I would consider it important what parameters are passed to these functions however I'm not sure this should be part of a unit test.</p>