title: .text() returning "<Button />" instead of the button's text
body: <p>Basically what's in the title. I have the following code in a component I am writing a test for:</p>
  <p><code>&lt;Button&gt;Edit&lt;/Button&gt; // &lt;- Material UI Button component</code></p>
  <p>And this line in my test is failing:</p>
  <p><code>expect(wrapper.find(Button).text()).to.equal(&quot;Edit&quot;);</code></p>
  <p>with this error:</p>
  <pre><code>assert.strictEqual(received, expected)
  
  Expected value to strictly be equal to:
    &quot;Edit&quot;
  Received:
    &quot;&lt;Button /&gt;&quot;
  
  Message:
    expected '&lt;Button /&gt;' to equal 'Edit'
  </code></pre>
  <p>Any idea what might be happening?</p>