gistfile1.txt

   validates :password, format: { with: /\d/, message: "must contain at least one number" },
                    allow_blank: true
  validates :password, format: { with: /[a-zA-Z]/, message: "must contain at least one letter" },
                    allow_blank: true

     it "should require a letter" do
        numbers = "12345678"
        user = User.new(@attr.merge(:password => numbers, :password_confirmation => numbers))
        user.should have(1).error_on(:password)
        user.errors_on(:password).should include("must contain at least one letter")
      end

      it "should require a number" do
        letters = "abcdefgh"
        user = User.new(@attr.merge(:password => letters, :password_confirmation => letters))
        user.should have(1).error_on(:password)
        user.errors_on(:password).should include("must contain at least one number")
      end