title: Running the same flutter test after each other. 1 succeeds and 1 fails
body: <p>Im starting with creating Flutter tests and running into a problem with 2 tests that are exactly the same, but only 1 succeeds.</p>
  
  <p>Gist: 
  <a href="https://gist.github.com/Mooibroek/bd6c02e5b56e4b03409ee1839a2e0b23" rel="noreferrer">https://gist.github.com/Mooibroek/bd6c02e5b56e4b03409ee1839a2e0b23</a></p>
  
  <p>The second one fails with this error:</p>
  
  <pre><code>The following TestFailure object was thrown running a test:
    Expected: exactly one matching node in the widget tree
    Actual: ?:&lt;zero widgets with widget matching predicate (Closure: (dynamic) =&gt; bool) (ignoring
    offstage widgets)&gt;
     Which: means none were found but one was expected
  
  When the exception was thrown, this was the stack:
  #4      main.&lt;anonymous closure&gt; (file:///Users/nicepants/Projects/flutter/generic_flutter/test/register_test.dart:38:5)
  &lt;asynchronous suspension&gt;
  #5      testWidgets.&lt;anonymous closure&gt;.&lt;anonymous closure&gt; (package:flutter_test/src/widget_tester.dart:108:25)
  </code></pre>
  
  <p>Line 38 is the line where we assert if the button is found. I added most of the related code in the GIST, let me know if you need more.</p>
  
  <p>Is it in any way possible that there is some hidden state left from the previous test? Or is this not suppose to work.</p>