title: Rspec/Rails: how to verify that no method of a class is called
body: <p>I'd like to write something like this:</p>
  
  <pre><code>it 'does not invoke any MyService' do
      MyService.should_not_receive(&lt;any method&gt;)
      tested_method
  end
  </code></pre>
  
  <p>I do not want to list all methods of MyService explicitly because this would lead to a brittle test that could give false positives silently if new methods were added to MyService.</p>