title: How to mock string functions in Javascript and qUnit
body: <p>Mocking normal functions of objects works usually like this:</p>
  
  <pre><code>objToMock.funcToMock = function (param1, ...) {
      equal(param1, 'expectedValue', 'param1 passed correctly');
  }
  </code></pre>
  
  <p>If I try this with a native string function, an error wis thrown:</p>
  
  <pre><code>var name = 'test_string';
  name.split = function (limiter) {
      ok(true, 'split called');
  }
  </code></pre>
  
  <p>error:</p>
  
  <pre><code>Source: TypeError: Cannot create property 'split' on string 'test_string'
  </code></pre>
  
  <p>Is there a blocking mechanism for built-in string functions? I thought strings are also objects with functions.
  Accessing the prototype of 'test_string' does not work, as 'prototype' is undefined.</p>
  
  <p>Searching the web/stackoverflow is quite hard as "javascript", "string", "split" and "mock" are too generic search values.</p>
  
  <p>Thanks for your help!</p>