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Moq Setup does not work as expected in a separate class

I am using moq version 4.2 to unit test some controllers of web api 2 with EF as the ORM. Since a lot of tests need a mocked IEntityRepository<User> so I use a static method in a separate class called TestHelper to create such a fake repository so that I can just call this method in all the tests where needed. Here is the static method:
internal static IEntityRepository<User> GetSingleUserMockRepository(User user, bool noTracking = true, params Expression<Func<User, object>>[] properties)
{
var userRepository = new Mock<IEntityRepository<User>>();
if (properties.Any())
userRepository.Setup(x => x.GetSingleInclude(user.Key, noTracking, properties)).Returns(Task.FromResult(user));
else
userRepository.Setup(x => x.GetSingle(user.Key, noTracking)).Returns(Task.FromResult(user));
return userRepository.Object;
}
I am not showing other method details here because don't think they're relevant to my problem. The thing is when calling this static method in my tests and pass the returned user repository into controllers the test will fail because it cannot find the user i.e. Setup didn't work!. However, if I repeat the test implementation within my tests to create the mock repository as a local variable; everything works fine.
Namely, this doesn't work (where Devices is a navigation property on the User entity, again don't think the detail matters here) e.g. if I pass the returned userRepository into my controller the test will fail.:
var userRepository = TestHelper.GetSingleUserMockRepository(user, true, x=> x.Devices);
But this works e.g. if I just use a local variable in the test and pass the userRepository.Object into my controller everything works as expected:
var userRepository = new Mock<IEntityRepository<User>>();
userRepository.Setup(x => x.GetSingleInclude(user.Key, true, u => u.Devices)).Returns(Task.FromResult(user));
Can someone please explain why? I thought these two ways are equivalent but clearly not in practice.

This is maybe not a full answer (yet), but still to long to fit into a Stack Overflow comment.
When you do:
userRepository.Setup(x => x.GetSingleInclude(user.Key, noTracking, properties)).Returns(...);
you are saying: When GetSingleInclude is called with that user.Key and that noTracking and in particular that properties which is an array of expression trees, Moq shall return what you specify.
However, if Moq gets a call to GetSingleInclude where one or more of the arguments are not equal to the values you supplied, your setup is not relevant, and Moq returns instead the default value which is null.
(If you had used MockBehavior.Strict instead, it would have thrown an exception instead of silently just returning null, which could be more helpful for understanding the issue.)
So when are two arrays of expression trees equal? If Moq uses the default equality comparer for arrays, they are only "equal" when they are the same array instance. If Moq uses some entry-wise comparison, it will come down to whether each expression tree is equal as reference (i.e. same Expression<> instance). In any case you may have trouble.
The question is why it works in the other case. Does GetSingleInclude have special overloads for when the number of properties (expression trees) is little?
What is the result of running the code from this question?
I am saying that you may be facing the same problem as in the thread
Mocking and verifying call to method containing an Expression<Func<T,bool>> parameter.

Mocking the NHibernate JoinAlias with Moq

I have the following repository code that will return a Company object based on an ID value, searching across the standard Company table and an additional table named ExternalCompany.
public Company FindByIdJoin(long id)
{
ExternalCompany xcomp = null;
return Session.QueryOver<Company>()
.Where(p => p.ObjectId == id)
.JoinAlias(p => p.ExternalCompanies, () => xcomp, JoinType.LeftOuterJoin)
.SingleOrDefault<Company>();
}
The code returns values that I expect. However, the trouble I'm having is in writing a Moq unit test to handle the JoinAlias call.
In a simpler method, called FindById, the code is essentially the same except there is no line for JoinAlias. The unit test for this simpler method is:
[Test]
public void FindById_returns_Company_for_valid_Id()
{
// Arrange
Mock<IQueryOver<Company, Company>> mockQueryOver = new Mock<IQueryOver<Company, Company>>();
mockQueryOver.Setup(x => x.Where(It.IsAny<Expression<Func<Company, bool>>>())).Returns(mockQueryOver.Object);
mockQueryOver.Setup(x => x.SingleOrDefault()).Returns(fake_Company);
// Act
var result = _repository.FindById(fake_Company.ObjectId);
// Assert
Assert.IsNotNull(result);
mockQueryOver.VerifyAll();
}
This test works and passes without a problem (fake_Company and _repository are defined elsewhere).
The problem is trying to put a test together for the FindByIdJoin call. I have tried using an additional Setup line like this (which goes between the Where and SingleOrDefault Setup lines):
mockQueryOver.Setup(x => x.JoinAlias(It.IsAny<Expression<Func<Company>>>(), It.IsAny<Expression<Func<ExternalCompany>>>(), JoinType.LeftOuterJoin)).Returns(mockQueryOver.Object);
The system tells me that "the best overloaded method match for IQueryOver ... has some invalid arguments."
So, I tried a few other variations on the Setup, but could not find a workable pattern.
My question is: what Setup arguments will work for JoinAlias so that I can properly test the FindByIdJoin method? Thanks!

The particular overload of JoinAlias you are using is
IQueryOver<TRoot, TSubType> JoinAlias(
Expression<Func<TSubType, object>> path,
Expression<Func<object>> alias,
JoinType joinType);
So, your setup needs to match this. Based on how you setup your IQueryOver mock, the correct setup would then be
mockQueryOver.Setup(x => x.JoinAlias(
It.IsAny<Expression<Func<Company, object>>>(),
It.IsAny<Expression<Func<object>>>(),
JoinType.LeftOuterJoin))
.Returns(mockQueryOver.Object);

Shouldn't MOQ be used for behaviour tests? Such Data access tests seem to be state dependent and I think using mock objects for such a system under test is an overkill.

Moq chaining expressions results in parameter count mismatch

I'm attempting to mock a repository using Moq. I have found multiple questions with similar issues but none that I found were able to solve the issue I'm having.
So I'm using a repository that can be downloaded here. More specifically, the repository itself can be viewed here and the query extensions I'm using can be seen here.
This is what my tests setup looks like:
// A List<> of fakes.
this.containers = Builder<Container>.CreateListOfSize(10).Build();
// Here I'm trying to set up the mock object for the query.
this.containerRepoMock.Setup(p => p.
Query(It.IsAny<Expression<Func<Container, bool>>>())
.Include(It.IsAny<Expression<Func<Container, object>>>())
.Select())
.Returns((Expression<Func<Container, bool>> query, Expression<Func<Container, object>> include) =>
this.containers.AsQueryable().Where(query).Include(include));
// Tell the service to use the mock repository.
this.containerService = new ContainerService(mockUnitOfWork.Object);
This is the service method that I'm trying to test:
public ContainerDto GetContainerAndItsCategories(int containerId)
{
var entity = Repository
.Query(w => w.ContainerId == containerId)
.Include(c => c.Categories)
.Select();
var output = Mapper.EntityToDto(entity.SingleOrDefault());
return output;
}
Whenever i try to run this service method in my test using the mock repository it throws an exception "System.Reflection.TargetParameterCountException: Parameter count mismatch."
I have tried adding extra object arguments to the .Returns() method in the mock setup without any success. It always throws the same exception. From what I have been reading Moq is somewhat limited when it comes to testing expressions however i have seen examples where people are doing similar things with success.
Since the Include() and Query() methods return a IQueryFluent() instance instead of direct expressions i have tried to use the QueryFluent() class in the Moq return() method but haven't been able to do it successfully with the queryable(compile errors).
Any help would be greatly appreciated, really want to be able to test this properly using unit tests.
Edit - Similar questions that I've looked at
Moq + Unit Testing - System.Reflection.TargetParameterCountException: Parameter count mismatch
Moq Params TargetParameterCountException : Parameter count mismatch Exception

The issue is with this line:
this.containerRepoMock.Setup(p => p.
Query(It.IsAny<Expression<Func<Container, bool>>>())
.Include(It.IsAny<Expression<Func<Container, object>>>())
.Select())
You cannot (as far as my Moq knowledge goes) set up a group of methods in one Setup call. Furthermore, in this line:
.Returns((Expression<Func<Container, bool>> query, Expression<Func<Container, object>> include) =>
this.containers.AsQueryable().Where(query).Include(include));
You're telling Moq to expect (in the Setup call) a call to a single method with two parameters (query and include) and to pass those to the Returns lambda here. This is obviously not the case: you have calls to two one-parameter methods, and so Moq throws a parameter mismatch exception.
You'll need to break it down into its components and setup mocks for the return values. Also, since you want to make use of the Expression objects you'll need to save those off for use at the end. For example:
var containerRepoMock = new Mock<IRepositoryAsync<Container>>();
var queryFluentQueryMock = new Mock<IQueryFluent<Container>>();
var queryFluentIncludeMock = new Mock<IQueryFluent<Container>>();
Expression<Func<Container, bool>> query = null;
containerRepoMock.Setup(p => p.Query(It.IsAny<Expression<Func<Container, bool>>>()))
.Callback<Expression<Func<Container, bool>>>(q => query = q)
.Returns(queryFluentQueryMock.Object);
Expression<Func<Container, object>> include = null;
queryFluentQueryMock.Setup(p => p.Include(It.IsAny<Expression<Func<Container, object>>>()))
.Callback<Expression<Func<Container, object>>>(i => include = i)
.Returns(queryFluentIncludeMock.Object);
queryFluentIncludeMock.Setup(p => p.Select())
.Returns(containers.AsQueryable().Where(query).Include(include));
Please forgive any compilation errors, I didn't download the libraries you linked to to try this out

Passing a predicate function parameter in moq fails

I am trying to use moq to mock a function on my licence class.
The licence class has the following interface:
Licence TryGetLicence(Predicate<Licence> filter);
In my integration test I am using mef to lazy load objects. My class finds the mef loaded objects and needs to check if there are licences available. For my test I create two objects, one of which can be licenced. I want to use moq to only return a licence for this object and null for the other, just as the real class would. The problem I am having is that moq doesn’t like me passing in a predicate. I’m not sure if moq just doesn’t handle predicates in this way or am I just implementing this wrong?
Here are the lines of code I have in my test that sets up moq for the above interface:
var lic = new Licence
{
LicId = Guid.Parse("53024D4E-3A01-4489-A341-753D04748EB9"),
LicName = "test",
Count = 1,
ExpiryDate = DateTime.Now.AddDays(2)
};
var mockAgent = new Mock<ILicenceAgent>();
mockAgent.Setup(x => x.TryGetLicence (y => y.LicId == lic.LicId)) Returns(lic);
This builds but when the last line is hit it throws an Unsupported expression exception.
For other tests I have used:
mockAgent.Setup(x => x. TryGetLicence (It.IsAny<Predicate<Licence>>())).Returns(lic);
I can’t use this for my new test as it would return a valid licence for both objects I have loaded.
Can moq be used in the way I am trying to use it?

This should solve the problem:
Predicate<Licence> predicate = y => y.LicId == lic.LicId;
mockAgent.Setup(x => x.TryGetLicence (predicate)).Returns(lic);
When you create the predicate inside Setup call, lambda expression is evaluated as a part of the expression that will be passed as a parameter. We prevent that by making sure it's only a delegate on the line above.

If you have 2 licences - lic1 and lic2, you can setup mock like this:
mockAgent.Setup(x => x.TryGetLicence(It.Is<Predicate<Licence>>(/* add your specific condition for licence1 */ ))).Returns(lic1);
mockAgent.Setup(x => x.TryGetLicence(It.Is<Predicate<Licence>>(/* add your specific condition for licence2 */ ))).Returns(lic2);

How to mock results of Enumerable.Any() extension using moq

I'm using mongo driver, and trying to fake results of any to test whether Insert or Update was called based on results.
Here's piece of code I think relevant:
_context = _collection.AsQueryable();
if (_context.Any(s => s.Id == id))
{
...
after that I'm calling either _collection.Update() or _collection.Insert().
Here's what I tried so far with the unit test:
var collectionMock = new Mock<MongoCollection<Storage>>();
var queriableMock = new Mock<IQueryable<Storage>>();
queriableMock.Setup(q => Enumerable.Any(q)).Returns(() => false);
...
collectionMock.Setup(c => c.AsQueryable()).Returns(() => queriableMock.Object);
collectionMock.Setup(c => c.Save(It.IsAny<Storage>()));
I'm getting exception
"Expression references a method that does not belong to the mocked
object: q => q.Any()"

The Setup method takes a lambda that is not executed but is interpreted so that the mock can identify methods/properties of the mock object that will be called during the test and what should be returned/thrown/called back/etc.
Moq doesn't know the implementation of Enumerable.Any<T>(this T item), and therefore cannot figure out what methods or properties of T will be accessed or what they should do/return.
Therefore, in order to mock a call to Enumerable.Any, you need to identify what methods/properties of your object it, in turn, calls, and then mock those.
You can find the implementation here. Simply follow the call path and mock out everything Any needs to call.