title: Rspec: Testing to make sure email is not sent
body: <p>I am running a test to make sure emails are not sent to certain users:</p>
  
  <pre><code>it "does not send reminders to users who are not subscribed" do
          expect(ReminderMailer).not_to receive(:send_reminder).with("whatever", user.id).and_return(double(deliver_now: true))
          book.send_reminders("whatever", user.id)
        end
  </code></pre>
  
  <p>Book.rb</p>
  
  <pre><code>def send_reminders(medium, user_id)
      ReminderMailer.send_reminder(medium, user_id).deliver_now
  end
  </code></pre>
  
  <p>But the current test is saying:</p>
  
  <blockquote>
    <p>and_return is not supported with negative message expectations</p>
  </blockquote>
  
  <p>If I remove the and_return portion:</p>
  
  <pre><code>it "does not send reminders to users who are not subscribed" do
          expect(ReminderMailer).not_to receive(:send_reminder).with("whatever", user.id)
          book.send_reminders("whatever")
        end
  </code></pre>
  
  <p>Then the test fails because:</p>
  
  <blockquote>
    <p>undefined method `deliver_now' for nil:NilClass</p>
  </blockquote>
  
  <p>How can I test that an action mailer method with specific parameters are <em>not</em> called?</p>