Hartl Rails Tutorial: upcase-ing email address in user_test

Question

I'm about halfway through the Rails tutorial (excellent, btw), and have a little question. Is there a reason that this test uses duplicate_user.email = @user.email.upcase and not the more succinct duplicate_user.email.upcase ?

Here is the full test.

test "email addresses should be unique" do
    duplicate_user = @user.dup
    duplicate_user.email = @user.email.upcase
    @user.save
    assert_not duplicate_user.valid?
end

As far as I can tell, the test performs correctly doing it either way.

Answer 1

I'm not familiar with the tutorial but you seem to be asking why the test is not written as:

test "email addresses should be unique" do
  duplicate_user = @user.dup
  duplicate_user.email.upcase
  @user.save
  assert_not duplicate_user.valid?
end

In this case, the line duplicate_user.email.upcase will just return the upcased email. It will not affect the attribute on the object. The test still passes because the duplicate_user has the same email address as the original @user, satisfying the test spec that email addresses should be unique.

What the test is actually doing is verifying that the code recognises an upcased email to be the same as a downcased email. In such a case, the original line in the test has the effect of assigning to the email attribute of the duplicate_user an upcased version of the email address.