Dependency injection in Xunit project

Question

I am working on an ASP.Net Core MVC Web application.

My Solution contains 2 projects:

One for the application and
A second project, dedicated to unit tests (XUnit).

I have added a reference to the application project in the Tests project.

What I want to do now is to write a class in the XUnit Tests project which will communicate with the database through entity framework.

What I was doing in my application project was to access to my DbContext class through constructor dependency injection.

But I cannot do this in my tests project, because I have no Startup.cs file. In this file I can declare which services will be available.

So what can I do to get a reference to an instance of my DbContext in the test class?

Try this xunit di support built into xunit framework: nuget.org/packages/Xunit.Di, so that you can inject services dependencies the same way as you do for any other applications. — cli
– cli, Commented Oct 3, 2021 at 12:00

Mohsen Esmailpour · Accepted Answer · 2022-12-13 11:49:21Z

45

You can implement your own service provider to resolve DbContext.

public class DbFixture
{
    public DbFixture()
    {
        var serviceCollection = new ServiceCollection();
        serviceCollection
            .AddDbContext<SomeContext>(options => options.UseSqlServer("connection string"),
                ServiceLifetime.Transient);

        ServiceProvider = serviceCollection.BuildServiceProvider();
    }

    public ServiceProvider ServiceProvider { get; private set; }
}

public class UnitTest1 : IClassFixture<DbFixture>
{
    private ServiceProvider _serviceProvider;

    public UnitTest1(DbFixture fixture)
    {
        _serviceProvider = fixture.ServiceProvider;
    }

    [Fact]
    public void Test1()
    {
        using (var context = _serviceProvider.GetService<SomeContext>())
        {
        }
    }
}

But bear in your mind using EF inside a unit test is not a good idea and it's better to mock DbContext.

The Anatomy of Good Unit Testing

edited Dec 13, 2022 at 11:49

answered Jun 19, 2018 at 6:37

Mohsen Esmailpour

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15 Comments

Bob5421 Over a year ago

What is DatabaseSeeder ? Should i put DbFixture in a Service subfolder ?

Mohsen Esmailpour Over a year ago

Oops copy paste mistake. You can put DbFixture anywhere inside test project. I create TestSetup or TestInfrastructure folder and put such classes in these folders.

Bob5421 Over a year ago

Instead of your line with AddEntityFrameworkSqlServer, i am using this: serviceCollection.AddDbContext<BDDContext>(options => options.UseSqlServer("connection string") Is there a big difference ?

Mohsen Esmailpour Over a year ago

No both works fine and AddEntityFrameworkSqlServer registers additional services.

Mohsen Esmailpour Over a year ago

@Matt I fixed the broken link.

|

A. Wheatman · Accepted Answer · 2019-04-21 04:54:38Z

7

You can use Xunit.DependencyInjection

answered Apr 21, 2019 at 4:54

A. Wheatman

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2 Comments

noelicus Over a year ago

Expanding on what this does and why it's better than other approaches would be super useful here. Also adding a small sample demonstrating how it looks when used would be great .

ListenSoftware Louise Ai Agent Over a year ago

stackoverflow.com/questions/63269460/… Working through the problem

elektromntr · Accepted Answer · 2021-03-27 21:52:18Z

0

You can to use package Microsoft.EntityFrameworkCore.InMemory

var _dbContextOptions = new DbContextOptionsBuilder<DbContext>().UseInMemoryDatabase(Guid.NewGuid().ToString()).Options;

And then

var context = new DbContext(_dbContextOptions);

answered Mar 27, 2021 at 21:52

elektromntr

11 bronze badge

Comments

Paul Adam · Accepted Answer · 2019-03-15 07:45:02Z

-1

For unit tests you need to mock your context.

There is a great nuget package for mocking that is called Moq.

Some help to get you started:

public ClassName : IDisposable
{
    private SomeClassRepository _repository;
    private Mock<DbSet<SomeClass>> _mockSomeClass;

    public ClassName() 
    {
        _mockSomeClass = new Mock<DbSet<SomeClass>>();

        var mockContext = new Mock<IApplicationDbContext>();
        mockContext.SetupGet(c => c.SomeClass).Returns(_mockSomeClass.Object);

        _repository = new SomeClassRepository(mockContext.Object);
    }

    public void Dispose()
    {
        // Anything you need to dispose
    }

    [Fact]
    public void SomeClassTest()
    {
        var someClass = new SomeClass() { // Initilize object };

        _mockSomeClass.SetSource(new[] { someClass });

        var result = _repository.GetSomethingFromRepo( ... );

        // Assert the result
    }
}

For integration tests you do the same thing but the setup is:

_context = new ApplicationDbContext();

Make sure that your TestClass inherits from IDisposable (TestClass : IDisposable) so that you can dispose the context after each test.

https://xunit.github.io/docs/shared-context

edited Mar 15, 2019 at 7:45

answered Jun 19, 2018 at 11:11

Paul Adam

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1 Comment

Mirek Michalak Over a year ago

There's no SetUp, atrribute in xunit. Use constructor instead.

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