Question

What’s the best practices way to test that a model is valid in rails?

For example, if I have a User model that validates the uniqueness of an email_address property, how do I check that posting the form returned an error (or better yet, specifically returned an error for that field).

I feel like this should be something obvious, but as I’m quickly finding out, I still don’t quite have the vocabulary required to effectively google ruby questions.

Answer 1

The easiest way would probably be:

class UserEmailAddressDuplicateTest < ActiveSupport::TestCase
  def setup
    @email = "[e-mail]"
    @user1, @user2 = User.create(:email => @email), User.new(:email => @email)
  end

  def test_user_should_not_be_valid_given_duplicate_email_addresses
    assert !@user2.valid?
  end

  def test_user_should_produce_error_for_duplicate_email_address
    # Test for the default error message.
    assert_equal "has already been taken", @user2.errors.on(:email)
  end
end

Of course it’s possible that you don’t want to create a separate test case for this behaviour, in which case you could duplicate the logic in the setup method and include it in both tests (or put it in a private method).

Alternatively you could store the first (reference) user in a fixture such as fixtures/users.yml, and simply instantiate a new user with a duplicate address in each test.

Refactor as you see fit!