# File lib/fog/aws/requests/iam/detach_role_policy.rb, line 32
        def detach_role_policy(role_name, policy_arn)
          response = Excon::Response.new

          if policy_arn.nil?
            raise Fog::AWS::IAM::ValidationError, "1 validation error detected: Value null at 'policyArn' failed to satisfy constraint: Member must not be null"
          end

          managed_policy = self.data[:managed_policies][policy_arn]

          unless managed_policy
            raise Fog::AWS::IAM::NotFound, "Policy #{policy_arn} does not exist."
          end

          unless self.data[:roles].key?(role_name)
            raise Fog::AWS::IAM::NotFound.new("The role with name #{role_name} cannot be found.")
          end

          role = self.data[:roles][role_name]
          role[:attached_policies].delete(policy_arn)
          managed_policy["AttachmentCount"] -= 1

          response.body = {"RequestId" => Fog::AWS::Mock.request_id}
          response
        end