title: What's the difference between RSpec's subject and let? When should they be used or not?
body: <p><a href="http://betterspecs.org/#subject" rel="noreferrer">http://betterspecs.org/#subject</a> has some info about <code>subject</code> and <code>let</code>. However, I am still unclear on the difference between them. Furthermore, the SO post <a href="https://stackoverflow.com/questions/12869026/what-is-the-argument-against-using-before-let-and-subject-in-rspec-tests">What is the argument against using before, let and subject in RSpec tests?</a> said it is better to not use either <code>subject</code> or <code>let</code>. Where shall I go? I am so confused.</p>