unit testing with mock

Question

I have to unit test a function ( SendMessageNetSkyToAgenceGrp ), and inside this function there is a service that I want to mock ( EnvoyerNotificationSms.SendMessageNetSky(signalRMessage) ): Here is the code i want to test:

public void SendMessageNetSkyToAgenceGrp(
            int agenceId,
            string message,
            string name,
            bool addAgenceLibInMsg = true,
            SignalRMessageThemeEnum theme = SignalRMessageThemeEnum.Information)
        {
            Agence agence = AgenceCoreService.GetAgenceById(agenceId);

            if (agence == null || (string.IsNullOrEmpty(agence.Libelle) && addAgenceLibInMsg))
            {
                return;
            }

            string finalMessage = (message + (addAgenceLibInMsg ? agence.Libelle : ""));

            string groupName = string.Empty;

            if (theme == SignalRMessageThemeEnum.NotificationSms)
            {
                groupName = SignalRConstantes.GRP_SMSAGENCE + SignalRConstantes.SEPARATOR + agenceId;
            } 
            else
            {
                groupName = (SignalRConstantes.GRP_AGENCE + SignalRConstantes.SEPARATOR + agenceId);
            }

            SignalRMessage signalRMessage = new SignalRMessage(name, "", finalMessage, groupName, theme);

            EnvoyerNotificationSms.SendMessageNetSky(signalRMessage);
        } 

And here is the test code:

[Fact(DisplayName = "Vérifier l'appel à l'infra IEnvoyerNotificationSms")]
        public void SendMessageNetSkyToAgenceGrp_CasNormal_ResultatOk()
        {
            // Arange            
            var envoyerNotificationSmMock = new Mock<IEnvoyerNotificationSms>();
            envoyerNotificationSmMock.Setup(envoyerNotifSms => envoyerNotifSms.SendMessageNetSky(It.IsAny<SignalRMessage>())).Verifiable();

            var SignalRCoreService = LocalIocManager.Resolve<ISignalRCoreService>();
            // Act 
            LocalIocManager.IocContainer.UseInstance(envoyerNotificationSmMock.Object, IfAlreadyRegistered.Replace);            
            SignalRCoreService.SendMessageNetSkyToAgenceGrp(56, "testMessage", "name", true, SignalRMessageThemeEnum.NotificationSms);

            // Assert
            envoyerNotificationSmMock.Verify(envoyerNotifSms => envoyerNotifSms.SendMessageNetSky(It.IsAny<SignalRMessage>()), Times.Once());
        }

But when I execute the test I get an error telling me that the service I want to mock is null ( EnvoyerNotificationSms.SendMessageNetSky(signalRMessage); ) The error is: 'Object reference not set to an instance of an object.' in the line EnvoyerNotificationSms.SendMessageNetSky(signalRMessage);

How can I solve this issue?

Answer 1

After checking the problem was the order of these lines:

var SignalRCoreService = LocalIocManager.Resolve<ISignalRCoreService>();
            // Act 
LocalIocManager.IocContainer.UseInstance(envoyerNotificationSmMock.Object, IfAlreadyRegistered.Replace);            

In the second line has no effect, because the service i want to mock is already created in the first line. So the solution was to change the order of the two lines.