title: Failed: Template parse errors: 'mat-card' is not a known element
body: <p>When I'm running Karma "ng test" for my project, I'm getting below error,</p>
  
  <p>Failed: Template parse errors: 'mat-card' is not a known element</p>
  
  <p>But the application is working fine with mat-card tag when we run "ng serve". We are using angular 6. requesting guidance on this.</p>