Validating boolean value in Rspec and Rails

I'm pretty confused how to validate boolean values in Rspec and Rails. I understand everything except for false and nil are taken as true in Ruby. But when I use MySQL with Rails, it uses 1 for true and 0 for false (if my understanding is correct).

I have the following model spec. I'd like to test boolean value for superuser attribute.

• How can I write specs here?
• How can I write implementation code here?

• Are my specs and implementation code specific to a specific database (like MySQL and PostgreSQL)?

  require 'spec_helper'
  describe User do
    before(:each) do
      @valid_attributes = {
        :username => "mike",
        :password => "super_encryped_password",
        :email => "mike@example.com",
        :superuser => true
      }  
    end
  
    it "should create a new instance given valid attributes" do
      User.create!(@valid_attributes)
    end
  
    it "should have true or false for superuser" do
      @valid_attributes[:superuser] = "hello"
      User.new(@valid_attributes).should have(1).error_on(:superuser)
    end
  end