title: Angular, Jasmine : TypeError Cannot read property 'filter' of undefined.
body: <p>I'm trying to unit test the MatRadioGroup wrapper but keep getting <code>TypeError: Cannot read property 'filter' of undefined jasmine</code>.</p>
  
  <p>The spec should pass but I don't get why filter undefined error being thrown while the test is being run.</p>
  
  <p>Below is the spec:</p>
  
  <pre><code>it('should test the properties of the component', () =&gt; {
  options = [
      {
          value: 'Option 1',
          displayValue: 'Option 1',
      }, {
          value: 'Option 2',
          displayValue: 'Option 2',
          checked: true,
      }
  ];
  component.options = options;
  component.color = 'primary';
  fixture.detectChanges();
  let radioElement = fixture.debugElement.query(By.css('.mat-radio-button'));
  console.log(radioElement);
  expect(radioElement.attributes['ng-reflect-color']).toEqual('primary');});
  </code></pre>
  
  <p>Here's the stackblitz: <a href="https://stackblitz.com/edit/radio-group-wrapper" rel="nofollow noreferrer">https://stackblitz.com/edit/radio-group-wrapper</a></p>
  
  <p>Other suggestions for testing this wrapper are welcome.</p>