Unit testing validatable module of Devise

Console

Failures:

  1) User when email address is already taken 
     Failure/Error: it { should_not be_valid }
       expected valid? to return false, got true
     # ./spec/models/user_spec.rb:73:in `block (3 levels) in <top (required)>'

user.rb

class User < ActiveRecord::Base
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable

  attr_accessible :email, :password, :password_confirmation, :remember_me
end

user_spec.rb

require 'spec_helper'

describe User do
  before do
    @user = Fabricate(:user)
  end

  subject { @user }

  describe 'when email address is already taken' do
    before do
      user_with_same_email = @user.dup
      user_with_same_email.email = @user.email.upcase
      user_with_same_email.save
    end

    it { should_not be_valid }
  end
end

As sevenseacat on IRC pointed out, the test was still asserting @user instead of user_with_same_email. That's why it was returning true. Knowing that, I adjusted the test to be like this:

describe 'when email address is already taken' do
  before do
    @user_with_same_email = @user.dup
    @user_with_same_email.email = @user.email
    @user_with_same_email.save
  end

  subject { @user_with_same_email }

  it { should_not be_valid }
end

This solution got the test to pass.