如何调试此或可能的原因？ Moq.Verify上的用户代码未处理System.NullReferenceException

Question

I have something like this in my unit test

public class MyTestClass()
{
      private Mock<IAccountRepo> accountRepo;
       private AdminService adminService;

      [Setup]
      public void Setup()
      {
        accountRepo = fixture.Freeze<Mock<IAccountRepo>>();
        adminService = fixture.CreateAnonymous<AdminService>();
      }

      [Test]
      public Test()
      {
          accountRepo.Setup(x => x.Insert(It.IsAny<IUnitOfWork>(), It.IsAny<MyDomainObject>()));

            adminService.ApplyAdminFee(1, 1, today);

            accountRepo.Verify(x => x.Insert(It.IsAny<IUnitOfWork>(), It.Is<MyDomainObject>(a => a.Id == 1)));
      }
}

I get this error.

System.NullReferenceException was unhandled by user code
  Message=Object reference not set to an instance of an object.
  Source=Anonymously Hosted DynamicMethods Assembly
  StackTrace:
       at lambda_method(Closure , MyDomainObject )
       at Moq.It.<>c__DisplayClass2`1.<Is>b__1(TValue value)
       at Moq.Match`1.Matches(Object value)
       at Moq.Matcher.Matches(Object value)
       at Moq.MethodCall.Matches(IInvocation call)
       at Moq.Mock.<>c__DisplayClassc.<VerifyCalls>b__b(IInvocation i)
       at System.Linq.Enumerable.WhereListIterator`1.MoveNext()
       at System.Linq.Enumerable.Count[TSource](IEnumerable`1 source)
       at Moq.Mock.VerifyCalls(Interceptor targetInterceptor, MethodCall expected, Expression expression, Times times)
       at Moq.Mock.Verify[T](Mock mock, Expression`1 expression, Times times, String failMessage)
       at Moq.Mock`1.Verify(Expression`1 expression, Times times)
       at Test() in 383
  InnerException: 

I am not sure why.

Edit

I think I know what is happening. in my method I have 3 calls to the insert method(the insert method takes in an object).

So I have like

accountRepo.Insert(MyDomainObject);
accountRepo.Insert(MyOtherDomainObject);
accountRepo.Insert(MyOtherOtherDomainObject);

So maybe those 2 other inserts are overriding it? how can I get around this?

Answer 1

The problem is in here: It.Is<MyDomainObject>(a => a.Id == 1) . You can tell from the stack trace.

I would change it like this: It.Is<MyDomainObject>(a => a != null && a.Id == 1)