title: RSpec: How to test for a boolean return type?
body: <p>I'm using RSpec to test an API. I want to specify that one particular endpoint returns a boolean value, either <code>true</code> or <code>false</code>. This is an API to be used by other systems and languages, and so it's important for it to be an actual boolean, not merely something that Ruby will evaluate to <code>false</code> or <code>true</code>.</p>
  
  <p>But I don't see a way to do this because there's no <code>Boolean</code> type in Ruby.</p>