title: ag-grid unit testing in angular2- fixture.nativeElement.query is not a function
body: <p>I wrote a test case by using Karma/Jasmine for ag-grid in angular. In my test case just checking the ag-grid headers and getting error like "fixture.nativeElement.query is not a function" but i am not confident enough whether this is a right approach or not which i have written. If any one having idea please help me. </p>
  
  <p>This is my test case</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>it('to test the column headers',()=&gt;{
      fixture.nativeElement.query(By.css(".ag-fresh"))
      .map(function (header){
        return header.getText()
      }).then(function(headers){
        expect(headers).toEqual(['color','qty','price']);
      });
    });</code></pre>
  </div>
  </div>
  </p>