public async Task ItCreatesANewGamingGroupIfNotConsumingAnInvitationToAnExistingGamingGroup() { newUser = new NewUser() { UserName = "******", EmailAddress = "the email", GamingGroupInvitationId = null }; await userRegisterer.RegisterUser(newUser); firstTimeUserAuthenticatorMock.AssertWasCalled(mock => mock.CreateGamingGroupAndSendEmailConfirmation( Arg <ApplicationUser> .Matches(user => user.UserName == newUser.UserName && user.Email == newUser.EmailAddress), Arg <TransactionSource> .Is.Anything)); }