module ThoughtBot # :nodoc:
  module Shoulda # :nodoc:
    module ActiveRecord # :nodoc:
      module Assertions
        # Asserts that the given object can be saved
        #
        #  assert_save User.new(params)
        def assert_save(obj)
          assert obj.save, "Errors: #{pretty_error_messages obj}"
          obj.reload
        end

        # Asserts that the given object is valid
        #
        #  assert_valid User.new(params)
        def assert_valid(obj)
          assert obj.valid?, "Errors: #{pretty_error_messages obj}"
        end

        # Asserts that an Active Record model validates with the passed
        # <tt>value</tt> by making sure the <tt>error_message_to_avoid</tt> is not
        # contained within the list of errors for that attribute.
        #
        #   assert_good_value(User.new, :email, "user@example.com")
        #   assert_good_value(User.new, :ssn, "123456789", /length/)
        #
        # If a class is passed as the first argument, a new object will be
        # instantiated before the assertion.  If an instance variable exists with
        # the same name as the class (underscored), that object will be used
        # instead.
        #
        #   assert_good_value(User, :email, "user@example.com")
        #
        #   @product = Product.new(:tangible => false)
        #   assert_good_value(Product, :price, "0")
        def assert_good_value(object_or_klass, attribute, value, error_message_to_avoid = //)
          object = get_instance_of(object_or_klass)
          object.send("#{attribute}=", value)
          object.valid?
          assert_does_not_contain(object.errors.on(attribute), error_message_to_avoid, "when set to #{value.inspect}")
        end

        # Asserts that an Active Record model invalidates the passed
        # <tt>value</tt> by making sure the <tt>error_message_to_expect</tt> is
        # contained within the list of errors for that attribute.
        #
        #   assert_bad_value(User.new, :email, "invalid")
        #   assert_bad_value(User.new, :ssn, "123", /length/)
        #
        # If a class is passed as the first argument, a new object will be
        # instantiated before the assertion.  If an instance variable exists with
        # the same name as the class (underscored), that object will be used
        # instead.
        #
        #   assert_bad_value(User, :email, "invalid")
        #
        #   @product = Product.new(:tangible => true)
        #   assert_bad_value(Product, :price, "0")
        def assert_bad_value(object_or_klass, attribute, value,
                             error_message_to_expect = DEFAULT_ERROR_MESSAGES[:invalid])
          object = get_instance_of(object_or_klass)
          object.send("#{attribute}=", value)
          assert !object.valid?, "#{object.class} allowed #{value.inspect} as a value for #{attribute}"
          assert object.errors.on(attribute), "There are no errors on #{attribute} after being set to #{value.inspect}"
          assert_contains(object.errors.on(attribute), error_message_to_expect, "when set to #{value.inspect}")
        end

        def pretty_error_messages(obj)
          obj.errors.map { |a, m| "#{a} #{m} (#{obj.send(a).inspect})" }
        end

        private

        def get_instance_of(object_or_klass)
          if object_or_klass.is_a?(Class)
            klass = object_or_klass
            instance_variable_get("@#{klass.to_s.underscore}") || klass.new
          else
            object_or_klass
          end
        end
      end
    end
  end
end