it "should validate the uniqueness of a column" do
    class User < Sequel::Model
      validations.clear
      validates do
        uniqueness_of :username
      end
    end
    User.dataset.extend(Module.new {
      def fetch_rows(sql)
        @db << sql

        if sql == "SELECT * FROM users WHERE (username = 'willy') LIMIT 1" then
          yield({:id => 1, :username => "willy", :password => "test"})
        end
      end
    })

    @user = User.new(:username => "willy", :password => "anothertest")
    @user.should_not be_valid
    @user.errors.full_messages.should == ['username is already taken']

    @user.username = "pinky"
    @user.should be_valid
  end

  it "should not fail when trying to update a record when the unique value hasn't changed" do
    class User < Sequel::Model
      validations.clear
      validates do
        uniqueness_of :username
      end
    end
    User.dataset.extend(Module.new {
      def fetch_rows(sql)
        @db << sql

        yield({:id => 1, :username => "willy", :password => "test"})
      end
    })

    user = User[1]
    user.should be_valid
  end