gistfile1.rb

        it "should send an invitation notification" do
          InvitationMailer.stub!(:deliver_invitation)
          InvitationMailer.should_receive(:deliver_invitation).and_return(true)
          create_invitation
        end
        
        it "should send an invitation notification" do
          InvitationMailer.stub!(:deliver_invitation)
          InvitationMailer.should_not_receive(:deliver_invitation)
          create_invitation
        end