Develop Reference

Moq keeps throwing null reference exception

I am new to Moq having used Rhino mocks for a while. I am trying to stub a method so that is returns the information I expect but the actual line of code when running the test returns a null reference exception. Am I missing something obvious here? Below is my code:
public void GetResSystemClients(ResSystem resSystem)
{
ResSystemDetail = new ResSystemDetails() {ResSys = resSystem};
//RETURNS NULL REFERENCE EXCEPTION
var resClients = FileReader.ReadFile((c) => c.Where(x =>
x.ReservationSystem.Replace(" ", "").ToLowerInvariant().Contains(resSystem.ToString().ToLowerInvariant())));
ResSystemDetail.ResSystemClients = resClients
.Select(y => new ResSystemClient() {ClientCode = y.ClientCode, ClientName = y.ClientName})
.OrderBy(z => z.ClientCode).ToList();
}
Test Code
[SetUp]
public void SetUp()
{
mockFileReader = new Mock<IClientLookUpFileReader>(MockBehavior.Default);
sut = new ClientLookupModel();
}
[TestCase(ResSystem.Test)]
public void When_GetResSystemCalled_With_ResSystem_Return_CorrectClients(ResSystem system)
{
//Arrange
mockFileReader.Setup(x =>
x.ReadFile(It.IsAny<Func<List<ExtraClientInfo>, IEnumerable<ExtraClientInfo>>>()))
.Returns(new List<ExtraClientInfo>
{
new ExtraClientInfo
{
ClientName = "Test",
ClientCode = "XX"
},
new ExtraClientInfo
{
ClientName = "Test1",
ClientCode = "X1"
},
new ExtraClientInfo
{
ClientName = "Test2",
ClientCode = "X2"
},
});
//Act
sut.GetResSystemClients(system);
}
Read file code
public interface IClientLookUpFileReader
{
T ReadFile<T>(Func<List<ExtraClientInfo>, T> predicateFunc);
}
public class ClientLookUpFileReader : IClientLookUpFileReader
{
private const string filePath = "D:/PersistedModels/ClientInfo.json";
T IClientLookUpFileReader.ReadFile<T>(Func<List<ExtraClientInfo>, T> predicateFunc)
{
if (File.Exists(filePath))
{
var clientInfoList = new JavaScriptSerializer().Deserialize<List<ExtraClientInfo>>(System.IO.File.ReadAllText(filePath));
return predicateFunc(clientInfoList);
}
throw new Exception($"File not found at path {filePath}");
}
}

Moq Insert/Update with new Object initialization

public class UserService
{
IUserRepo userRepo;
UserService(IUserRepo repo)
{
userRepo = repo;
}
void AddUser(JsonData data)
{
User user = new User()
{
Name = data.name,
Number = data.Number
};
userRepo.Insert(user);
int id = user.id;
}
}
id is 0 when a unit test case is debugged, but when it is a proper call it returns proper primary key i.e. 1, 2, 3, etc.
Mock
class TestCases
{
Mock<IUserRepo> mockUserRepo = new Mock<IUserRepo>();
[Test]
public void test1()
{
//Arrange
JsonData obj = new JsonData()
{
Name = "Jane",
Number = "0563722992"
}
User dumpUser= new User()
{
Name = "Def",
Number = "8111"
};
mockUserRepo
.Setup(x => x.Insert(It.IsAny<User>()))
.Callback(() => dumpUser.Id = 1);
//Act
UserService u = new UserService(mockUserRepo.Object);
u.AddUser(obj);
//Assert
}
}
While debugging the unit test it seems that callback is unable to change the id to 1 when it passes through the method Insert().
Can anybody help how to tackle with this issue?

There is no need for
User dumpUser= new User()
{
Name = "Def",
Number = "8111"
};
As the method under test creates/initializes it's own instance within.
Capture the passed argument in the call back and update the desired member there
//...
userRepo
.Setup(x => x.Insert(It.IsAny<User>()))
.Callback((User arg) => arg.Id = 1);
//...

Return the result of a mocked method to another mocked method

I've got a class that has the following implementation:
public sealed class HotelRepository : IHotelRepository
{
private readonly string _dataSource;
public HotelRepository(string dataSource) => _dataSource = dataSource;
/// <inheritdoc />
public async Task<IEnumerable<Hotel>> GetAllAsync() =>
await Task.Run(() => JObject.Parse(File.ReadAllText(_dataSource))["hotels"].ToList().Select(x => x.ToObject<Hotel>()));
/// <inheritdoc />
public async Task<IEnumerable<Hotel>> GetListByMatchAsync(string name) =>
await GetAllAsync().ContinueWith(x => x.Result.Where(y => y.Name.Contains(name, StringComparison.CurrentCultureIgnoreCase)));
}
As you can see, the GetListByMatchAsync method calls GetAllAsync, then does some logic before returning the result.
When I tried to mock this repository for unit testing, I'm struggling to get a result out of GetListByMatchAsync as it always fails as a null reference exception.
Here's the unit test:
[TestCase("Test", "X")]
[TestCase("Hotel", "X")]
[TestCase("Name", "X")]
public async Task GetListByMatchAsync_GetHotelListByMatchingNameAsync_ReturnsFiveMatchingHotels(string name, string nonMatch)
{
_hotelRepositoryMock = new Mock<IHotelRepository>();
_hotelRepository = _hotelRepositoryMock.Object;
// Set up sample data.
var data = new List<Hotel>
{
new Hotel{Id = 1, Name = $"{name}", Description = "Description2", Location = "Location2", Rating = Rating.Two},
new Hotel{Id = 2, Name = $"{name.ToUpper()}", Description = "Description1", Location = "Location1", Rating = Rating.Five},
new Hotel{Id = 3, Name = $"{name.ToLower()}", Description = "Description2", Location = "Location2", Rating = Rating.Three},
new Hotel{Id = 4, Name = $"{name} {nonMatch}", Description = "Description2", Location = "Location2", Rating = Rating.One},
new Hotel{Id = 5, Name = nonMatch, Description = "Description2", Location = "Location2", Rating = Rating.One},
};
// Set up mock methods and ensure these method returns any sample data.
_hotelRepositoryMock.Setup(x => x.GetListByMatchAsync(It.IsAny<string>()));
_hotelRepositoryMock.Setup(x => x.GetAllAsync()).ReturnsAsync(data);
var result = await _hotelRepository.GetListByMatchAsync(name);
// Cast to list to make assertions.
var hotels = result.ToList();
Assert.That(hotels, Is.TypeOf<List<Hotel>>());
Assert.That(hotels.Count, Is.EqualTo(4));
}
How can I make this test work such that the GetListByMatchAsync mock method does some logic after calling the mocked GetAllAsync method?

First, the code that you have shown cannot possibly work because the methods that you are trying to set up are not virtual. Declare the methods you want to Setup as virtual.
Second, this is wrong:
_hotelRepositoryMock.Setup(x => x.GetListByMatchAsync(It.IsAny<string>()));
With this call, you're effectively setting up GetListByMatchAsync to return default(Task<IEnumerable<Hotel>>), i.e. null. That's obviously not what you want. Either:
use .Returns(...) to specify what the method should return; or,
use .CallBase() if the method should simply return whatever the implementation in the base class would return. (This is likely what you need.)

Unit Test Mocking an IHttpActionResult GetId method

I am creating some unit tests for a controller I have however I ran into a problem.
Basically I have the following:-
The Controller Method :-
[ResponseType(typeof(Attrib))]
public IHttpActionResult GetAttrib(int id)
{
var attrib = _attribsRepository.GetAttrib(id);
if (attrib == null)
{
return NotFound();
}
return Ok(attrib);
}
Its a simple Web API 2.0 method.
Then I have the Repository :-
public Attrib GetAttrib(int id)
{
return DbSet.FirstOrDefault(x=>x.Id == id);
}
And finally the Test Method:-
public class AttribsControllerTests
{
public Mock<IAttribsRepository> _attribsRepositoryMock;
public List<Attrib> AttribList;
public AttribsController AttribsController;
[SetUp]
public void Init()
{
_attribsRepositoryMock = new Mock<IAttribsRepository>();
AttribList = new List<Attrib>
{
new Attrib()
{
Id = 1,
AttributeId = "Cro",
AttributeName = "Crossing",
AttributeType = "Tech",
AttributeValue = 1
},
new Attrib()
{
Id = 2,
AttributeId = "Dri",
AttributeName = "Dribbling",
AttributeType = "Tech",
AttributeValue = 2
},
new Attrib()
{
Id = 3,
AttributeId = "Fin",
AttributeName = "Finishing",
AttributeType = "Tech",
AttributeValue = 3
}
};
}
[Test]
public void Get_Check_That_Id1_Returns_Crossing()
{
//Arrange
_attribsRepositoryMock.Setup(t => t.GetStaticAttribs()).Returns(AttribList.AsQueryable());
//Act
var attribsController = new AttribsController(_attribsRepositoryMock.Object);
var result = attribsController.GetAttrib(1) as OkNegotiatedContentResult<Attrib>;
//Assert
Assert.IsNotNull(result);
Assert.AreEqual(AttribList[0].AttributeName, "Cor");
}
}
For some reason, the result is always null, so its not hitting the controller correctly.
Any ideas why this could happen? When debugging, the correct Mock Repository is hitting the controller, and it should have the 3 entries in it.
Any help will be very much appreciated.

You setup GetStaticAttribs but it is used nowhere in the example you showed. You were suppose to setup IAttribsRepository.GetAttrib
Based on your example
[Test]
public void Get_Check_That_Id1_Returns_Crossing() {
//Arrange
var id = 1;
_attribsRepositoryMock.Setup(t => t.GetAttrib(id)).Returns(AttribList[0]);
var attribsController = new AttribsController(_attribsRepositoryMock.Object);
//Act
var result = attribsController.GetAttrib(id) as OkNegotiatedContentResult<Attrib>;
//Assert
Assert.IsNotNull(result);
Assert.IsNotNull(result.Content);
Assert.AreEqual(result.Content.AttributeName, "Crossing");
}

Mock method of system-under-test with Moq

I have the following three methods in the CompanyApplication class (along with the supporting factories and services listed):
public ResultSet<CompanyDto> AddCompany(CompanyDto companyDto)
{
var result = new CompanyDto();
var company = new Company();
Mapper.Map(companyDto, company);
using (ITransaction t = _transactionFactory.Create())
{
company = _companyService.Add(company);
t.Commit();
}
Mapper.Map(company, result);
return new ResultSet<CompanyDto>(1, new[] { result });
}
public ResultSet<CompanyContactDto> AddCompanyContact(CompanyContactDto companyContactDto)
{
var result = new CompanyContactDto();
var company = new Company();
var contact = new CompanyContact();
Mapper.Map(companyContactDto, contact);
using (ITransaction t = _transactionFactory.Create())
{
var contactCompanies = FindByIdJoin<Company, CompanyDto>(companyContactDto.CompanySK);
Mapper.Map(contactCompanies.Data.First(), company);
company.CompanyContacts.Add(contact);
company = _companyService.Update(company);
t.Commit();
}
Mapper.Map(contact, result);
return new ResultSet<CompanyContactDto>(1, new[] { result });
}
public ResultSet<T_DtoType> FindByIdJoin<T_DbType, T_DtoType>(long id)
{
IAbstractRepository<T_DbType> repository = EnsureRepository<T_DbType>();
T_DbType entity = repository.FindByIdJoin(id);
return (entity == null ? null : MapResultSetToDto<T_DbType, T_DtoType>(entity));
}
There are other objects in play here, which is why the FindByIdJoin has been made a separate method in the CompanyApplication class.
I have set up the testing class with some mocks and an instance of the CompanyApplication class:
private Mock<ICompanyRepository> _mockCompanyRepository;
private Mock<ICompanyDomain> _mockCompanyService;
private Mock<ITransactionFactory> _mockTransactionFactory;
private Mock<ITransaction> _mockTransaction;
private CompanyApplication _companyApplication;
[Setup]
public void SetUp()
{
_mockCompanyRepository = new Mock<ICompanyRepository>(MockBehavior.Strict);
_mockCompanyService = new Mock<ICompanyDomain>(MockBehavior.Strict);
_mockTransactionFactory = new Mock<ITransactionFactory>(MockBehavior.Strict);
_mockTransaction = new Mock<ITransaction>(MockBehavior.Strict);
_companyApplication = new CompanyApplication(
_mockCompanyRepository.Object,
_mockCompanyService.Object,
_mockTransactionFactory.Object);
}
I am successfully able to test the FindByIdJoin and AddCompany methods directly in Moq like this:
[Test]
public void CanFindCompanyByIdJoin()
{
var data = new Company {ObjectId = 1, Name = "Company1"};
_mockCompanyRepository.Setup(x => x.FindByIdJoin(It.Is<long>(arg => arg == data.ObjectId)))
.Returns(data);
var result = _companyApplication.FindByIdJoin<Company, CompanyDto>(data.ObjectId);
Assert.AreEqual(data.ObjectId, result.Data.First().ObjectId);
}
[Test]
public void CanAddCompany()
{
var data = new Company {ObjectId = 1, Name = "Company1"};
_mockCompanyService.Setup(x => x.Add(It.Is<Company>(arg => arg.ObjectId == data.ObjectId)))
.Returns(data);
_mockTransactionFactory.Setup(x => x.Create()).Returns(_mockTransaction.Object);
_mockTransaction.Setup(x => x.Commit());
_mockTransaction.Setup(x => x.Dispose());
var dto = new CompanyDto {ObjectId = 1, Name = "Company1"};
var result = _companyApplication.AddCompany(dto);
_mockCompanyService.Verify(t => t.Add(It.IsAny<Company>()));
}
Those two tests pass just fine. However, I'm having trouble coming up with a test for AddCompanyContact, because it calls FindByIdJoin as part of its flow, and that seems to be getting in the way.
Specifically, is there a way to mock var contactCompanies = FindByIdJoin<Company, CompanyDto>(companyContactDto.CompanySK) in a test for the AddCompanyContact method?
Thanks!

There is two alternatives that i see depending on the amount of work that you want to do.
Wrap that call into a object and instantiate it using a IOC container. This is the one that i feel would take the most effort if you are not using one already.
Turn that call into a Func and make a method without that parameter that does the call. This approach has the disadvantage that the top call will be untestable but will allow access to the rest of the method.
Example Below:
public ResultSet<CompanyContactDto> AddCompanyContact(CompanyContactDto companyContactDto)
{
AddCompanyContact(CompanyContactDto, ()=>
{
return FindByIdJoin<Company, CompanyDto> companyContactDto.CompanySK);
}
}
public ResultSet<CompanyContactDto> AddCompanyContact(CompanyContactDto companyContactDto, Func<WhateverTheMethodReturns> findIdReplacement)
{
var result = new CompanyContactDto();
var company = new Company();
var contact = new CompanyContact();
Mapper.Map(companyContactDto, contact);
using (ITransaction t = _transactionFactory.Create())
{
var contactCompanies = findIdReplacement();
Mapper.Map(contactCompanies.Data.First(), company);
company.CompanyContacts.Add(contact);
company = _companyService.Update(company);
t.Commit();
}
Mapper.Map(contact, result);
return new ResultSet<CompanyContactDto>(1, new[] { result });
}

I was over complicating the problem... since AddCompanyContact calls FindByIdJoin, all I needed to do was mock the same interface that is used in FindByIdJoin.
Lesson learned: mock interfaces, not classes.