title: Rails Minitest crashing when tests fail
body: <p>Minitest crashes every time a test fails when I run <code>rails test</code> (Rails 5 and Ruby 2.4.2). For example, I forced a simple test to fail by switching the <code>assert</code> to <code>assert_not</code>:</p>
  
  <pre><code>Failure: TransactionTest#test_transaction_should_be_valid [/home/.../test/models/transaction_test.rb:11]: Expected true to be nil or false
  
  /home/.../.rvm/gems/ruby-2.4.2/gems/railties-5.1.4/lib/rails/test_unit/reporter.rb:70:in `method': undefined method `test_transaction_should_be_valid' for class `Minitest::Result' (NameError)
  </code></pre>
  
  <p>If the test passes, then the entire report is successful and I get the report summary. If only one test fails I get the error report above. I defined <code>test_transaction_should_be_valid</code> in my <code>transaction_test.rb</code> file and the proof of it is that it runs smoothly when the test passes.</p>
  
  <p>I'm stuck on this now. Any ideas as to what might be causing this?</p>