title: fetch-mock does not mock my fetch
body: <p>here is the code snippet:</p>
  
  <pre><code>var fetch = require("node-fetch");
  var fetchMock = require("fetch-mock");
  
  function setupMockBlockChainExplorer() {
    fetchMock.mock("https://cardanoexplorer.com/api/addresses/summary/DdzFFzCqrhsmagp4fDZpcY9UaBJk4Z8GaDfxqMCSwxPs3PnVoXmJWUZcgAxw3diCHVYauontEfk7YGeAu2LvAwq3aG2XQ8Mtsz7Vc8LA", {
      "status" : 200,
      "body" : "override"
    });
  }
  
  async function makeRequest(url, method = "get", body = null, headers = null) {
    const res = await fetch(url, {
      method: method,
      headers: headers,
      body: body,
    });
  
    return res.json()
  };
  
  setupMockBlockChainExplorer();
  
  var req = makeRequest("https://cardanoexplorer.com/api/addresses/summary/DdzFFzCqrhsmagp4fDZpcY9UaBJk4Z8GaDfxqMCSwxPs3PnVoXmJWUZcgAxw3diCHVYauontEfk7YGeAu2LvAwq3aG2XQ8Mtsz7Vc8LA");
  
  // I would expect it to print "override" but it prints the http response from the real request instead
  req.then(console.log)
  </code></pre>
  
  <p>So I'm trying to override a HTTP request as you can see in the code above, but I'm still hitting the real URL with fetch. I have read the fetch-mock docs (<a href="http://www.wheresrhys.co.uk/fetch-mock/installation.html" rel="noreferrer">http://www.wheresrhys.co.uk/fetch-mock/installation.html</a>) and I also tried setting the config like this:</p>
  
  <pre><code>fetchMock.config = Object.assign(fetchMock.config, {
      "fetch": fetch
  });
  </code></pre>
  
  <p>but with no luck. What am I doing wrong?</p>