title: Mock API in Unit Tesing on Nativescript Core
body: <p>I'm implementing unit testing in my mobile app project with nativescript core. I want to mock api in unit testing but I can't do it, So this is my code</p>
  
  <pre><code>// model that I want to test
  const myfunction = async (): Promise&lt;myInterface&gt; =&gt; {
    const response = await fetch("myURL", {
      method: "GET",
      headers: { "Content-Type": "application/json" }
    });
    const { status, data }: { status: string, data?: any } = await response.json();
    if (!status || status !== "ok") {
      throw new Error("failed fetching from host, status:" + status);
    }
  
    return data;
  }
  </code></pre>
  
  <pre><code>// my unit testing
  
  import * as dataModel from "../../../shared/models/data";
  
  describe('data', () =&gt; {
    describe('myfunction', () =&gt; {
      it('get data from api', async () =&gt; {
        try {
          // I want to mock api in this place
          const response = await dataModel.myfunction();
        } catch(err) { console.log(err); }
      });
    });
  });
  </code></pre>
  
  <p>Does it have some plugin or something that can mock api from fetch with this mobile app nativescript core?</p>