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Unit Testing with Specification Pattern and Unit of Work is not returning data on setup

I have a generic Repository with the Unit of Work pattern setup to utilize the Specification Pattern which works great but now I am trying to Unit test it and it seems my setup isn't returning anything when specifying what to return.
Repository Snippet
internal class Repository<T> : IRepository<T> where T : BaseEntity
{
protected readonly ApplicationDbContext _context;
public Repository(ApplicationDbContext context)
{
_context = context;
}
public IEnumerable<T> Find(ISpecification<T> specification = null)
{
return ApplySpecification(specification);
}
private IQueryable<T> ApplySpecification(ISpecification<T> spec)
{
return SpecificationEvaluator<T>.GetQuery(_context.Set<T>().AsQueryable(), spec);
}
}
}
Snippet of Specification
public class GetStocksForCurrentDaySpecification : BaseSpecification<Stock>
{
public GetStocksForCurrentDaySpecification() : base(x => x.DateInserted.Day == DateTime.Today.Day) { }
}
Snippet of me calling it
_unitOfWork.Repository<Stock>().Find(new GetStocksForCurrentDaySpecification());
This all works perfectly when running my code.
Here is my Unit Test where I do setup.
[Fact]
public void Job_Should_Execute()
{
var stockList = new List<Stock>();
stockList.Add(new Stock
{
Id = Guid.NewGuid(),
DateInserted = DateTime.Now,
Exchange = "ASX",
LongName = "Long Name",
MarketOpenPrice = 1.26M,
MarketPreviousClosePrice = 1.56M,
MarketPrice = 1.3M,
ShortName = "Short Name",
Symbol = "LGN"
});
var stockRepositoryMock = new Mock<IRepository<Stock>>();
stockRepositoryMock.Setup(m => m.Find(new GetStocksForCurrentDaySpecification())).Returns(stockList.ToArray());
var unitOfWorkMock = new Mock<IUnitOfWork>();
unitOfWorkMock.Setup(m => m.Repository<Stock>()).Returns(stockRepositoryMock.Object).Verifiable();
var job = new YahooStockMarketJob(new HttpClient(), unitOfWorkMock.Object, new EventPublisher(_listeners), _configuration);
job.Execute();
unitOfWorkMock.Verify();
}
When debugging, the following line returns an empty array instead of an array with one item it.
// Returns empty array
var stockRepositoryMock = new Mock<IRepository<Stock>>();
stockRepositoryMock.Setup(m => m.Find(new GetStocksForCurrentDaySpecification())).Returns(stockList.ToArray());

In your mock object you are setting up the Find method with a specific instance of GetStocksForCurrentDaySpecification. During your test you are passing a different instance of GetStocksForCurrentDaySpecification and since those are not the same it won't use that setup.
If you want your setup to work with your test you either need to use the same instance or allow any instance of the object by using It.IsAny<T>.
E.g.
// Returns empty array
var stockRepositoryMock = new Mock<IRepository<Stock>>();
stockRepositoryMock
.Setup(m => m.Find(It.IsAny<GetStocksForCurrentDaySpecification>()))
.Returns(stockList.ToArray());

Unit Testing a Class With A Private Constructor

I am trying to test a class that only has a private constructor. This is for a course registration system. The courses do not get create via our application, therefore we intentionally have no public constructor. Instead we use EF to get the courses that are already in the database, and register students to them.
I am trying to test the register method of the Course class, however I have no way of creating an instance. I could use
course = (Course)Activator.CreateInstance(typeof(Course), true);, but then I don't have a way to setup the necessary properties since those are private.
What is the recommended approach for unit testing without a constructor?
This is a slimmed down version of the code.
public class Course
{
private Course()
{
}
public int Id { get; private set; }
public string Name { get; private set; }
public bool Open { get; private set; }
public virtual ICollection<Student> Students { get; private set; }
public void Register(string studentName)
{
if (Open)
{
var student = new Student(studentName);
Students.Add(student);
}
}
}
// Usage //
using (var db = new SchoolContext())
{
var course = db.Courses.Include(x => x.Students).Where(x => x.Name == courseName).First();
course.Register(studentName);
db.SaveChanges();
}
// Unit Test //
[Fact]
public void CanRegisterStudentForOpenClass(){
// HERE I HAVE NO WAY TO CHANGE THE OPEN VARIABLE
var course = (Course)Activator.CreateInstance(typeof(Course), true);
course.Register("Bob");
}

Yes you can using reflexion. your code is neraly there;
you can get properties and fields of the types with typeof(Course).GetProperty("PropertyName") then you can use SetValue to set the desired value, and pass as parameter first the instance to modify then the value.
in your case true;
note: in your example you will need to add the Collection of students too, if your Open is true.
Here there is a working example:
[Fact]
public void CanRegisterStudentForOpenClass()
{
var course = (Course)Activator.CreateInstance(typeof(Course), true);
typeof(Course).GetProperty("Open").SetValue(course, true, null);
ICollection<Student> students = new List<Student>();
typeof(Course).GetProperty("Students").SetValue(course, students, null);
course.Register("Bob");
Assert.Single(course.Students);
}

If you would rather not use reflection, then I recommend you use internal classes (instead of private) and using the InternalsVisibleToAttribute on your implementation assembly.
You can find more about the attribute here. Here's a quick guide on how you can use it!
Step 1. Add this attribute to your assembly that wants its internal code tested.
[assembly: InternalsVisibleToAttribute("MyUnitTestedProject.UnitTests")]
Step 2. Change private to internal.
public class Course
{
internal Course()
{
}
public int Id { get; internal set; }
public string Name { get; internal set; }
public bool Open { get; internal set; }
public virtual ICollection<Student> Students { get; internal set; }
/* ... */
}
Step 3. Write your tests like normal!
[Fact]
public void CanRegisterStudentForOpenClass()
{
var course = new Course();
course.Id = "#####";
course.Register("Bob");
}

As a few people have mentioned here, unit testing something private is either a code smell, or a sign you're writing the wrong tests.
In this case, what you would want to do is use EF's in-memory database if you're using Core, or mocking with EF6.
For EF6 You can follow the docs here
I would say rather than newing your dbContext where you do, pass it in via Dependency Injection. If that's beyond the scope of the work you're doing, (I'm assuming this is actual coursework, so going to DI may be overkill) then you can create a wrapper class that takes a dbcontext and use that in place.
Taking a few liberties with where this code is called from...
class Semester
{
//...skipping members etc
//if your original is like this
public RegisterCourses(Student student)
{
using (var db = new SchoolContext())
{
RegisterCourses(student, db);
}
}
//change it to this
public RegisterCourses(Student student, SchoolContext db)
{
var course = db.Courses.Include(x => x.Students).Where(x => x.Name == courseName).First();
course.Register(studentName);
db.SaveChanges();
}
}
[Fact]
public void CanRegisterStudentForOpenClass()
{
//following after https://learn.microsoft.com/en-us/ef/ef6/fundamentals/testing/mocking#testing-query-scenarios
var mockCourseSet = new Mock<DbSet<Course>>();
mockCourseSet.As<IQueryable<Course>>().Setup(m => m.Provider).Returns(data.Provider);
mockCourseSet.As<IQueryable<Course>>().Setup(m => m.Expression).Returns(data.Expression);
mockCourseSet.As<IQueryable<Course>>().Setup(m => m.ElementType).Returns(data.ElementType);
mockCourseSet.As<IQueryable<Course>>().Setup(m => m.GetEnumerator()).Returns(data.GetEnumerator());
//create an aditional mock for the Student dbset
mockStudentSet.As.........
var mockContext = new Mock<SchoolContext>();
mockContext.Setup(c => c.Courses).Returns(mockCourseSet.Object);
//same for student so we can include it
mockContext.Include(It.IsAny<string>()).Returns(mockStudentSet); //you can change the isAny here to check for Bob or such
var student = Institution.GetStudent("Bob");
var semester = Institution.GetSemester(Semester.One);
semester.RegisterCourses(student, mockContext);
}
If you're using EFCore you can follow it along from here

You can fake private constructors and members using TypeMock Isolator or JustMock (both paid) or using MS Fakes (only available in VS Enterprise).
There is also a free Pose library that allows you to fake access to properties.
Unfortunately, the private constructor can't be forged. Therefore, you will need to create an instance of the class using reflection.
Add package.
Open namespace:
using Pose;
Test code:
[Fact]
public void CanRegisterStudentForOpenClass()
{
var course = (Course)Activator.CreateInstance(typeof(Course), true);
ICollection<Student> students = new List<Student>();
Shim studentsPropShim = Shim.Replace(() => Is.A<Course>().Students)
.With((Course _) => students);
Shim openPropShim = Shim.Replace(() => Is.A<Course>().Open)
.With((Course _) => true);
int actual = 0;
PoseContext.Isolate(() =>
{
course.Register("Bob");
actual = course.Students.Count;
},
studentsPropShim, openPropShim);
Assert.Equal(1, actual);
}

You can create a JSON representation of your default instance and deserialize it with Newtonsoft.
Something like this:
using System.Reflection;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
using privateConstructor;
namespace privateConstructorTest
{
[TestClass]
public class CourseTest
{
[TestMethod]
public void Register_WhenOpenIsTrue_EnableAddStudents()
{
// Arrange
const string json = #"{'Id': 1, 'name':'My Course', 'open':'true', 'students':[]}";
var course = CreateInstance<Course>(json);
// Act
course.Register("Bob");
// Assert
Assert.AreEqual(1, course.Students.Count);
}
[TestMethod]
public void Register_WhenOpenIsFalse_DisableAddStudents()
{
// Arrange
const string json = #"{'Id': 1, 'name':'My Course', 'open':'false', 'students':[]}";
var course = CreateInstance<Course>(json);
// Act
course.Register("Bob");
// Assert
Assert.AreEqual(0, course.Students.Count);
}
private static T CreateInstance<T>(string json) =>
JsonConvert.DeserializeObject<T>(json, new JsonSerializerSettings
{
ConstructorHandling = ConstructorHandling.AllowNonPublicDefaultConstructor,
ContractResolver = new ContractResolverWithPrivates()
});
public class ContractResolverWithPrivates : CamelCasePropertyNamesContractResolver
{
protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
{
var prop = base.CreateProperty(member, memberSerialization);
if (prop.Writable) return prop;
var property = member as PropertyInfo;
if (property == null) return prop;
var hasPrivateSetter = property.GetSetMethod(true) != null;
prop.Writable = hasPrivateSetter;
return prop;
}
}
}
}
In order to have a cleaner test class, you can extract the JSON strings and the helper code that creates the instance.

Too many interfaces and wrappers?

I'm slowly starting to get the hang of unit-testing and mocking, but it's a slow process. I have tried unit testing this Active Directory code. The question is not strictly relevant to AD.
class ActiveDirectoryQueryer {
DirectorySearcher mSearcher;
public ActiveDirectoryQueryer() {
var searcher = new DirectorySearcher(...);
}
public void GetAllMailEntries() {
MailEntries =
mSearcher
.FindAll()
.Select(result => result.GetDirectoryEntry())
.Select(BuildNewADUser)
.ToList();
}
static ActiveDirectoryUser BuildNewADUser(DirectoryEntry pDirectoryEntry) {
return ActiveDirectoryUser.Create(
pDirectoryEntry.Guid,
(pDirectoryEntry.Properties["name"].Value ?? "").ToString(),
(pDirectoryEntry.Properties["mail"].Value ?? "").ToString()
);
}
So, I would like to unit test the GetAllMailEntries method. In order to do this using MOQ I've had to manually generate interfaces and wrappers for various .NET types, and changed many of the above references to interfaces instead (like IDirectoryEntry). Each of the IXxxx interfaces below has an associated wrapper class XxxxWrapper. In total I added at least 12 new source files just for this one test. Here's what I've ended up with for the unit test:
[TestMethod]
public void TestGetAllMailEntries() {
var mockSearcher = new Mock<IDirectorySearcher>();
var mockResultCollection = new Mock<ISearchResultCollection>();
var mockSearchResult = new Mock<ISearchResult>();
var mockDirectoryEntry = new Mock<IDirectoryEntry>();
var mockPropertyCollection = new Mock<IPropertyCollection>();
var nameMockPropertyValueCollection = new Mock<IPropertyValueCollection>();
var mailMockPropertyValueCollection = new Mock<IPropertyValueCollection>();
const string name = "SomeNameValue";
const string mailAddress = "SomeMailAddress";
nameMockPropertyValueCollection.SetupGet(pvc => pvc.Value).Returns(name);
mailMockPropertyValueCollection.SetupGet(pvc => pvc.Value).Returns(mailAddress);
mockPropertyCollection.SetupGet(pc => pc["name"]).Returns(nameMockPropertyValueCollection.Object);
mockPropertyCollection.SetupGet(pc => pc["mail"]).Returns(mailMockPropertyValueCollection.Object);
mockDirectoryEntry.SetupGet(de => de.Properties).Returns(mockPropertyCollection.Object);
mockSearchResult.Setup(sr => sr.GetDirectoryEntry()).Returns(mockDirectoryEntry.Object);
mockResultCollection.Setup(results => results.GetEnumerator()).Returns(new List<ISearchResult> { mockSearchResult.Object }.GetEnumerator());
mockSearcher.Setup(searcher => searcher.FindAll()).Returns(mockResultCollection.Object);
var queryer = new ActiveDirectoryQueryer(mockSearcher.Object);
queryer.GetAllMailEntries();
Assert.AreEqual(1, queryer.MailEntries.Count());
var entry = queryer.MailEntries.Single();
Assert.AreEqual(name, entry.Name);
Assert.AreEqual(mailAddress, entry.EmailAddress);
}
Is it normal to have this many interfaces and wrapper classes? (The wrappers are necessary since .NET types cannot otherwise implement my interfaces.)

I think my problem is mirroring the .NET structure too closely. I shouldn't wrap each and every .NET type all the way down till I get to just primitives. Rather, I should take the first opportunity to remove all dependencies as soon as I can. In this case it's with the DirectorySearcher class, and the FindAll method.
DirectorySearcher.FindAll returns a SearchResultCollection, but rather than thinking of my "wrapper" class as just an adapter to the .NET type, I should make more use of it.
Ignoring the implementation of IDisposable and other unnecessary code, my wrapper had looked like this:
public interface IDirectorySearcher : IDisposable {
ISearchResultCollection FindAll();
}
class DirectorySearcherWrapper : IDirectorySearcher {
DirectorySearcher mDirectorySearcher;
DirectorySearcherWrapper(DirectorySearcher pDirectorySearcher) {
mDirectorySearcher = pDirectorySearcher;
}
public static IDirectorySearcher Wrap(DirectorySearcher pDirectorySearcher) {
return new DirectorySearcherWrapper(pDirectorySearcher);
}
public ISearchResultCollection FindAll() {
return SearchResultCollectionWrapper.Wrap(mDirectorySearcher.FindAll());
}
}
Rather, I should take the opportunity to stop all dependencies right here. I don't have to return a .NET type or even just a wrapper to a .NET type, I can now use this interface to return whatever I want. IE: If what I want to get from the FindAll method is a bunch of ActiveDirectoryUsers, then return just that.
My code then becomes:
public interface IDirectorySearcher : IDisposable {
IEnumerable<ActiveDirectoryUser> FindAll();
}
class DirectorySearcherWrapper : IDirectorySearcher {
DirectorySearcher mDirectorySearcher;
DirectorySearcherWrapper(DirectorySearcher pDirectorySearcher) {
mDirectorySearcher = pDirectorySearcher;
}
public static IDirectorySearcher Wrap(DirectorySearcher pDirectorySearcher) {
return new DirectorySearcherWrapper(pDirectorySearcher);
}
public IEnumerable<ActiveDirectoryUser> FindAll() {
return
mDirectorySearcher
.FindAll()
.Cast<SearchResult>()
.Select(result => result.GetDirectoryEntry())
.Select(/*BuildNewADUser*/)
.ToList();
}
}
And the GetAllMailEntries method becomes simply:
public void GetAllMailEntries() {
MailEntries = mSearcher.FindAll();
}
And the unit test becomes:
[TestMethod]
public void TestGetAllMailEntries2() {
var mockSearcher = new Mock<IDirectorySearcher>();
mockSearcher
.Setup(s => s.FindAll())
.Returns(new[] {
ActiveDirectoryUser.Create(new Guid(), "Name", "EmailAddress")
});
var queryer = new ActiveDirectoryQueryer(mockSearcher.Object);
queryer.GetAllMailEntries();
Assert.AreEqual(1, queryer.MailEntries.Count());
var entry = queryer.MailEntries.Single();
Assert.AreEqual("Name", entry.Name);
Assert.AreEqual("EmailAddress", entry.EmailAddress);
}

Moq mocked DbContext returns null ObjectContext

I have a custom DisconnectedDbContext for use with self state tracking POCOs in a web app.
public abstract class DisconnectedDbContext : DbContext
{
protected DisconnectedDbContext()
{
var objAdapterContext = ((IObjectContextAdapter)this).ObjectContext;
}
}
I subclass this for some unit testing:
public class FruityContext : DisconnectedDbContext
{
public virtual DbSet<FruitBowl> FruitBowls { get; set; }
public virtual DbSet<Fruit> Fruits { get; set; }
}
And using Moq in a TestMethod as below:
[TestMethod]
public void CreateAFruityContext()
{
var dbc = new FruityContext();
Assert.IsNotNull(dbc);
var mockSet = new Mock<DbSet<FruitBowl>>();
var mockContext = new Mock<FruityContext>();
mockContext.Setup(m => m.FruitBowls).Returns(mockSet.Object);
var mo = mockContext.Object;
Assert.IsNotNull(mo);
}
Now this is not an actual TestMethod so I don't want to get sidetracked about that.
My problem is that for the creation of var dbc in this method, objAdapterContext in the constructor call is not null however for var mo it is null. I need objAdapterContext to be not null, as per non-mocked objects because I tap into this to handle the ObjectMaterialized event of the ObjectContext.
So the Moq wrapper is changing the behaviour of my code. Is there something I can do about this?

Use this:
mockSet.CallBase = true;
mockContext.CallBase = true;

Creating a hybrid of a mock and an anonymous object using e.g. Moq and AutoFixture?

I encountered a class during my work that looks like this:
public class MyObject
{
public int? A {get; set;}
public int? B {get; set;}
public int? C {get; set;}
public virtual int? GetSomeValue()
{
//simplified behavior:
return A ?? B ?? C;
}
}
The issue is that I have some code that accesses A, B and C and calls the GetSomeValue() method (now, I'd say this is not a good design, but sometimes my hands are tied ;-)). I want to create a mock of this object, which, at the same time, has A, B and C set to some values. So, when I use moq as such:
var m = new Mock<MyObject>() { DefaultValue = DefaultValue.Mock };
lets me setup a result on GetSomeValue() method, but all the properties are set to null (and setting up all of them using Setup() is quite cumbersome, since the real object is a nasty data object and has more properties than in above simplified example).
So on the other hand, using AutoFixture like this:
var fixture = new Fixture();
var anyMyObject = fixture.CreateAnonymous<MyObject>();
Leaves me without the ability to stup a call to GetSomeValue() method.
Is there any way to combine the two, to have anonymous values and the ability to setup call results?
Edit
Based on nemesv's answer, I derived the following utility method (hope I got it right):
public static Mock<T> AnonymousMock<T>() where T : class
{
var mock = new Mock<T>();
fixture.Customize<T>(c => c.FromFactory(() => mock.Object));
fixture.CreateAnonymous<T>();
fixture.Customizations.RemoveAt(0);
return mock;
}

This is actually possible to do with AutoFixture, but it does require a bit of tweaking. The extensibility points are all there, but I admit that in this case, the solution isn't particularly discoverable.
It becomes even harder if you want it to work with nested/complex types.
Given the MyObject class above, as well as this MyParent class:
public class MyParent
{
public MyObject Object { get; set; }
public string Text { get; set; }
}
these unit tests all pass:
public class Scenario
{
[Fact]
public void CreateMyObject()
{
var fixture = new Fixture().Customize(new MockHybridCustomization());
var actual = fixture.CreateAnonymous<MyObject>();
Assert.NotNull(actual.A);
Assert.NotNull(actual.B);
Assert.NotNull(actual.C);
}
[Fact]
public void MyObjectIsMock()
{
var fixture = new Fixture().Customize(new MockHybridCustomization());
var actual = fixture.CreateAnonymous<MyObject>();
Assert.NotNull(Mock.Get(actual));
}
[Fact]
public void CreateMyParent()
{
var fixture = new Fixture().Customize(new MockHybridCustomization());
var actual = fixture.CreateAnonymous<MyParent>();
Assert.NotNull(actual.Object);
Assert.NotNull(actual.Text);
Assert.NotNull(Mock.Get(actual.Object));
}
[Fact]
public void MyParentIsMock()
{
var fixture = new Fixture().Customize(new MockHybridCustomization());
var actual = fixture.CreateAnonymous<MyParent>();
Assert.NotNull(Mock.Get(actual));
}
}
What's in MockHybridCustomization? This:
public class MockHybridCustomization : ICustomization
{
public void Customize(IFixture fixture)
{
fixture.Customizations.Add(
new MockPostprocessor(
new MethodInvoker(
new MockConstructorQuery())));
fixture.Customizations.Add(
new Postprocessor(
new MockRelay(t =>
t == typeof(MyObject) || t == typeof(MyParent)),
new AutoExceptMoqPropertiesCommand().Execute,
new AnyTypeSpecification()));
}
}
The MockPostprocessor, MockConstructorQuery and MockRelay classes are defined in the AutoMoq extension to AutoFixture, so you'll need to add a reference to this library. However, note that it's not required to add the AutoMoqCustomization.
The AutoExceptMoqPropertiesCommand class is also custom-built for the occasion:
public class AutoExceptMoqPropertiesCommand : AutoPropertiesCommand<object>
{
public AutoExceptMoqPropertiesCommand()
: base(new NoInterceptorsSpecification())
{
}
protected override Type GetSpecimenType(object specimen)
{
return specimen.GetType();
}
private class NoInterceptorsSpecification : IRequestSpecification
{
public bool IsSatisfiedBy(object request)
{
var fi = request as FieldInfo;
if (fi != null)
{
if (fi.Name == "__interceptors")
return false;
}
return true;
}
}
}
This solution provides a general solution to the question. However, it hasn't been extensively tested, so I'd love to get feedback on it.

Probably there is a better why, but this works:
var fixture = new Fixture();
var moq = new Mock<MyObject>() { DefaultValue = DefaultValue.Mock };
moq.Setup(m => m.GetSomeValue()).Returns(3);
fixture.Customize<MyObject>(c => c.FromFactory(() => moq.Object));
var anyMyObject = fixture.CreateAnonymous<MyObject>();
Assert.AreEqual(3, anyMyObject.GetSomeValue());
Assert.IsNotNull(anyMyObject.A);
//...
Initially I tried to use fixture.Register(() => moq.Object); instead of fixture.Customize but it registers the creator function with OmitAutoProperties() so it wouldn't work for you case.

As of 3.20.0, you can use AutoConfiguredMoqCustomization. This will automatically configure all mocks so that their members' return values are generated by AutoFixture.
var fixture = new Fixture().Customize(new AutoConfiguredMoqCustomization());
var mock = fixture.Create<Mock<MyObject>>();
Assert.NotNull(mock.Object.A);
Assert.NotNull(mock.Object.B);
Assert.NotNull(mock.Object.C);