title: Enzyme Internal Error: configured enzyme adapter did not inherit from the EnzymeAdapter base class
body: <p>I get the following error when using enzyme 3 in my project (previously used enzyme 2 and everything worked):</p>
  
  <pre><code>Enzyme Internal Error: configured enzyme adapter did not inherit from the EnzymeAdapter base class
  
  
    at validateAdapter (node_modules/enzyme/build/validateAdapter.js:17:11)
    at Object.merge [as configure] (node_modules/enzyme/build/configuration.js:24:42)
    at Object.&lt;anonymous&gt; (test/enzyme-setup.js:4:8)
  </code></pre>
  
  <p><code>enzyme-setup.js</code> is the following file:</p>
  
  <pre><code>const Enzyme = require('enzyme');
  const Adapter = require('enzyme-adapter-react-15');
  
  Enzyme.configure({adapter: new Adapter()});
  </code></pre>