title: Why expect component to be truthy instead of defined
body: <p>This a a general question.</p>
  
  <p>When scaffolding a component with the Angular-cli, it creates the first test itself. </p>
  
  <p>It looks something like this: </p>
  
  <pre><code>it('should create', () =&gt; {
   expect(component).toBeTruthy();
  });
  </code></pre>
  
  <p>How Come it checks if it's Truthy and not Defined? And what is the difference?</p>
  
  <p>Thanks in advance :)</p>