How to get a service from anywhere using Microsoft.DependencyInjection?

Question

User911375783 posted

Hello,

I'm working on an ASP.NET Core 3.1 Web API project and I'm writing some integration tests. I created a database fixture that I use in my tests and for that I wanted to grab an IOptions object from the dependency injection container, but I don't know how to do that or even if it's possible.

Since I don't know how to use the dependency injection container, I wrote my fixture like:

        public MongoDbFixture()
        {
            // This is already configured in Startup as a singleton
            // but I don't know how to get the IOptions object here. To avoid all the following:
            var config = new ConfigurationBuilder()
                .AddJsonFile("appsettings.json")
                .AddJsonFile("appsettings.Testing.json").Build();


            var section = config.GetSection(nameof(RetroactiuneDbSettings));

            _settings = new RetroactiuneDbSettings();
            _settings.ConnectionString = section.GetValue<string>("ConnectionString");
            _settings.TokensCollectionName = section.GetValue<string>("TokensCollectionName");
            _settings.FeedbackCollectionName = section.GetValue<string>("FeedbackCollectionName");
            _settings.FeedbackReceiverCollectionName = section.GetValue<string>("FeedbackReceiverCollectionName");
            _settings.DatabaseName = section.GetValue<string>("DatabaseName");


            var client = new MongoClient(_settings.ConnectionString);
            Database = client.GetDatabase(_settings.DatabaseName);
        }

And my test, using xUnit 2.4 looks like:

    public class TestFeedbackReceiver : IClassFixture<WebApiTestingFactory>, IClassFixture<MongoDbFixture>
    {
        private readonly MongoDbFixture _mongoDb;
        private readonly HttpClient _client;

        public TestFeedbackReceiver(WebApiTestingFactory factory, MongoDbFixture mongoDbFixture)
        {
            _client = factory.CreateClient();
            _mongoDb = mongoDbFixture;
        }

        [Theory, AutoData]
        public async Task Test_CreateFeedbackReceiver_Ok(IEnumerable<FeedbackReceiverDto> items)
        {
            // Arrange
            await _mongoDb.DropAsync();
            var feedbackReceiversDto = items.ToList();
            var jsonContent = JsonSerializer.Serialize(feedbackReceiversDto);

            // Test
            var httpResponse = await _client.PostAsync("/api/v1/FeedbackReceiver/",
                new StringContent(jsonContent, Encoding.UTF8, "application/json"));

            // Assert
            httpResponse.EnsureSuccessStatusCode();
            var filter = new FilterDefinitionBuilder<FeedbackReceiver>().Empty;

            var createdDocs = await _mongoDb.FeedbackReceiverCollection.CountDocumentsAsync(filter);
            Assert.Equal(feedbackReceiversDto.Count(), createdDocs);
        }
    }

Is there a way I can retrieve an IOptions or another service from the dependency injection container which is used by my web application that is currently being tested?

Thank you!

Answer 1

User-474980206 posted

As a fixture is xunit’s version of DI, you can not use .net core services instead for fixtures in tests. I believe there been requests for injecting fixtures in fixtures.  If just want IOptions in tests, crate a fixture that returned an IOptions handler.

Also you could create a fixture that created services containers to use.

https://docs.microsoft.com/en-us/dotnet/core/extensions/dependency-injection

Note: while you can add services di support, your code will need to use when creating class instances, xunit will not do it for you.

Answer 2

User911375783 posted

Thank you for clarifying!

I've experimented a bit with the code, and I can use a simple class instead of a xunit fixture and give it the service/IOptions as a dependency

public class TestFeedbackReceiver : IClassFixture<WebApiTestingFactory>
{
    private readonly MongoDbFixture _mongoDb;
    private readonly HttpClient _client;

    public TestFeedbackReceiver(WebApiTestingFactory factory)
    {
        _client = factory.CreateClient();
        var dbSettings = factory.Services.GetRequiredService(typeof(IOptions<RetroactiuneDbSettings>));
        _mongoDb = new MongoDbFixture((IOptions<RetroactiuneDbSettings>) dbSettings);
    }
}