title: Karma highlight on subscribe
body: <p>Here is my Component code. I am trying to achieve full code coverage but fourth line was getting highlighted <code>res =&gt; { this.days = res</code>.</p>
  <p>Here is the code added for Details service</p>
  <pre><code>constructor(public detailsService:DashboardService ) {
     this.csvContent = '';
  }
  
  public getNonDealingDates() {
    try {
      this.detailsService.nonDealingdates().subscribe(
        res =&gt; { this.days = res },
        error =&gt; { throw error; }
      );
    } catch(excep){ }
  }
  </code></pre>
  <p>Here is my Unit test case.</p>
  <pre><code>it('should get non dealing dates ',() =&gt; {
    component.getNonDealingDates;
    expect(component.getNonDealingDates()).toBeUndefined();
  })
  </code></pre>
  <p>Do I need to include mock for subscribe? How can I mock for the above code?</p>