title: Rspec ignores uniqueness validation
body: <p>I don't want rspec to let me save two objects of the class with the same name, however it does. Is there something I'm missing?</p>
  
  <p>My model:</p>
  
  <pre><code>class Product &lt; ActiveRecord::Base
    validates :title, :description, :image_url, presence: true
    validates :price, numericality: {greater_than_or_equal_to: 0.01}
    validates :title, uniqueness: true
    validates :image_url, allow_blank: true, format: {
      with: %r{\.(gif|jpg|png)\Z}i,
      message: 'must be a URL for GIF, JPG or PNG image'
    }
  end
  </code></pre>
  
  <p>my test:</p>
  
  <pre><code>describe "when creating products with identical names" do
      let(:book1) { FactoryGirl.create(:product, title: 'identical') }
      let(:book2) { FactoryGirl.build(:product, title: 'identical') }
  
      it "raises unique validation error" do
          expect(book2).not_to be_valid
      end
  end
  </code></pre>
  
  <p>this is what I get:</p>
  
  <pre><code>1) Product when creating products with identical names raises unique validation error
       Failure/Error: expect(book2).not_to be_valid
         expected #&lt;Product id: nil, title: "identical", description: "Some crazy wibbles, that are fun", image_url: "freddie_mercury.jpg", price: #&lt;BigDecimal:7f995cdd1358,'0.5699E2',18(27)&gt;, created_at: nil, updated_at: nil&gt; not to be valid
  </code></pre>
  
  <p>I can even write two times FactoryGirl.create, it just saves.</p>
  
  <p>However if I switch over to rails console and try to create two objects with two identical names, I receive an error. Something wrong with my testing environment?</p>