MockQueryable

Extensions for mocking Entity Framework Core (EFCore) operations such ToListAsync, FirstOrDefaultAsync etc. by Moq, NSubstitute or FakeItEasy When writing tests for your application it is often desirable to avoid hitting the database. The extensions allow you to achieve this by creating a context – with behavior defined by your tests – that makes use of in-memory data.

When should I use it?

If you have something similar to the following code:

var query = _userRepository.GetQueryable();

await query.AnyAsync(x =>...)
await query.FirstOrDefaultAsync(x =>...)
query.CountAsync(x => ...)
query.ToListAsync()
//etc.

and you want to cover it by unit tests

How do I get started?

//1 - create a List<T> with test items
var users = new List<UserEntity>()
{
  new UserEntity{LastName = "ExistLastName", DateOfBirth = DateTime.Parse("01/20/2012")},
  ...
};

//2 - build mock by extension
var mock = users.AsQueryable().BuildMock();

//3 - setup the mock as Queryable for Moq
_userRepository.Setup(x => x.GetQueryable()).Returns(mock.Object);

//3 - setup the mock as Queryable for NSubstitute
_userRepository.GetQueryable().Returns(mock);

//3 - setup the mock as Queryable for FakeItEasy
A.CallTo(() => userRepository.GetQueryable()).Returns(mock);

Do you prefer DbSet?

//2 - build mock by extension
var mock = users.AsQueryable().BuildMockDbSet();

//3 - setup DbSet for Moq
var userRepository = new TestDbSetRepository(mock.Object);

//3 - setup DbSet for NSubstitute or FakeItEasy
var userRepository = new TestDbSetRepository(mock);

Do you use DbQuery?

//2 - build mock by extension
var mock = users.AsQueryable().BuildMockDbQuery();

//3 - setup the mock as Queryable for Moq
_userRepository.Setup(x => x.GetQueryable()).Returns(mock.Object);

//3 - setup the mock as Queryable for NSubstitute
_userRepository.GetQueryable().Returns(mock);

//3 - setup the mock as Queryable for FakeItEasy
A.CallTo(() => userRepository.GetQueryable()).Returns(mock);

Can I extend the mock object created by MockQueryable with custom logic?

MockQueryable creates for your tests a mock object based on in-memory data, but you can also add some custome logic to it.

var userId = Guid.NewGuid();
var users = new List<UserEntity>
{
    new UserEntity{Id = userId,LastName = "ExistLastName", DateOfBirth = DateTime.Parse("01/20/2012")},
   //etc. 
};
var mock = users.AsQueryable().BuildMockDbSet();

//Aditional setup for FindAsync
mock.Setup(x => x.FindAsync(userId)).ReturnsAsync((object[] ids) =>
{
    var id = (Guid)ids[0];
    return users.FirstOrDefault(x => x.Id == id);
});
var userRepository = new TestDbSetRepository(mock.Object);

//Execution FindAsync
var user = await ((DbSet<UserEntity>) userRepository.GetQueryable()).FindAsync(userId);

Check out the sample project

Where can I get it?

First, install NuGet.

If you are using Moq - then, install MockQueryable.Moq from the package manager console:

PM> Install-Package MockQueryable.Moq

If you are using NSubstitute - then, install MockQueryable.NSubstitute from the package manager console:

PM> Install-Package MockQueryable.NSubstitute

If you are using FakeItEasy - then, install MockQueryable.FakeItEasy from the package manager console:

PM> Install-Package MockQueryable.FakeItEasy

Can I use it with my favorite mock framework?

You can install MockQueryable.EntityFrameworkCore from the package manager console:

PM> Install-Package MockQueryable.EntityFrameworkCore

or even MockQueryable.Core

PM> Install-Package MockQueryable.Core