I am writing unit tests using xunit and moq for services in a servic fabric application.

I am passing the mocks like this

private static UsageDataQueueService CreateUsageDataQueueService(
            Mock<IServiceBusClientFactory> serviceBusClientFactoryMock )
        {
            // Exception is being thrown at this line below
            serviceBusClientFactoryMock ??= new Mock<IServiceBusClientFactory>();
            return new UsageDataQueueService(serviceBusClientFactoryMock.Object);
        }

Then test code is ( I have removed the asserts because it is unrelated):

[Fact]
        public async Task QueueUsageData()
        {
            // arrange
            Mock<IServiceBusClientFactory> serviceBusClientFactoryMock = new Mock<IServiceBusClientFactory>();
            serviceBusClientFactoryMock
                .Setup(factory => factory.CreateServiceBusClient(It.IsAny<string>()))
                .Returns(It.IsAny<IServiceBusClient>());

            // act
            UsageDataQueueService usageDataQueueService = CreateUsageDataQueueService(serviceBusClientFactoryMock: serviceBusClientFactoryMock);
           
        }

I am getting Null Reference Exception. Please help. Is this much context enough to answer the question or is more details needed?

CodePudding user response：

As pointed out by @Alexander Petrov in comments, problem lies in Returns(It.IsAny(). It must return either concrete instance or IServiceBusClient mock.