title: Testing Typescript Interface with Jest
body: <p>Below is my interface and test file.  When I run jest tests against it for code coverage, it keeps saying that lines 1 and 2 are not covered by the tests.  Is code coverage for interfaces something that is even possible? Or should I exclude any interfaces from the coverage reports?</p>
  
  <p><code>index.tsx</code></p>
  
  <pre><code>export interface StoreState {
      languageName: string;
      enthusiasmLevel: number;
  }
  </code></pre>
  
  <p><br/>
  <code>index.test.tsx</code></p>
  
  <pre><code>import { StoreState } from '../types';
  
  it('has a languageName of "TypeScript"', () =&gt; {
      const state: StoreState = { languageName: 'TypeScript', enthusiasmLevel: 3 };
      expect(state.languageName).toEqual('TypeScript');
  });
  
  it('has an enthusiasm level of 3', () =&gt; {
    const state: StoreState = { languageName: 'TypeScript', enthusiasmLevel: 3 };
    expect(state.enthusiasmLevel).toEqual(3);
  });
  </code></pre>