how to unit test asp.net core application with constructor dependency injection

ganjan picture ganjan · Jun 9, 2016 · Viewed 55.7k times · Source

I have a asp.net core application that uses dependency injection defined in the startup.cs class of the application:

    public void ConfigureServices(IServiceCollection services)
    {

        services.AddDbContext<ApplicationDbContext>(options =>
            options.UseSqlServer(Configuration["Data:FotballConnection:DefaultConnection"]));


        // Repositories
        services.AddScoped<IUserRepository, UserRepository>();
        services.AddScoped<IUserRoleRepository, UserRoleRepository>();
        services.AddScoped<IRoleRepository, RoleRepository>();
        services.AddScoped<ILoggingRepository, LoggingRepository>();

        // Services
        services.AddScoped<IMembershipService, MembershipService>();
        services.AddScoped<IEncryptionService, EncryptionService>();

        // new repos
        services.AddScoped<IMatchService, MatchService>();
        services.AddScoped<IMatchRepository, MatchRepository>();
        services.AddScoped<IMatchBetRepository, MatchBetRepository>();
        services.AddScoped<ITeamRepository, TeamRepository>();

        services.AddScoped<IFootballAPI, FootballAPIService>();

This allows something like this:

[Route("api/[controller]")]
public class MatchController : AuthorizedController
{
    private readonly IMatchService _matchService;
    private readonly IMatchRepository _matchRepository;
    private readonly IMatchBetRepository _matchBetRepository;
    private readonly IUserRepository _userRepository;
    private readonly ILoggingRepository _loggingRepository;

    public MatchController(IMatchService matchService, IMatchRepository matchRepository, IMatchBetRepository matchBetRepository, ILoggingRepository loggingRepository, IUserRepository userRepository)
    {
        _matchService = matchService;
        _matchRepository = matchRepository;
        _matchBetRepository = matchBetRepository;
        _userRepository = userRepository;
        _loggingRepository = loggingRepository;
    }

This is very neat. But becomes a problem when I want to unit test. Because my test library does not have a startup.cs where I setup dependency injection. So a class with these interfaces as params will just be null.

namespace TestLibrary
{
    public class FootballAPIService
    {
        private readonly IMatchRepository _matchRepository;
        private readonly ITeamRepository _teamRepository;

        public FootballAPIService(IMatchRepository matchRepository, ITeamRepository teamRepository)

        {
            _matchRepository = matchRepository;
            _teamRepository = teamRepository;

In the code above, in the test library, _matchRepository and _teamRepository, will just be null. :(

Can I do something like ConfigureServices, where I define dependency injection in my test library project?

Answer

madjack picture madjack · Nov 3, 2017

Although @Kritner's answer is correct, I prefer the following for code integrity and better DI experience:

[TestClass]
public class MatchRepositoryTests
{
    private readonly IMatchRepository matchRepository;

    public MatchRepositoryTests()
    {
        var services = new ServiceCollection();
        services.AddTransient<IMatchRepository, MatchRepositoryStub>();

        var serviceProvider = services.BuildServiceProvider();

        matchRepository = serviceProvider.GetService<IMatchRepository>();
    }
}