BaseTests.cs

[TestClass]
public abstract class BaseTest
{
    public static ServiceProvider serviceProvider;
    public IMyService _myService;
    [AssemblyInitialize]
    public static void SetUp(TestContext context)
    {
        IServiceCollection services = new ServiceCollection();
        services.AddTransient<IMyService, MyService>();
        //build services
        serviceProvider = services.BuildServiceProvider();
    }
    [TestInitialize]
    public void InitializeTest()
    {
    //resolve services
    _myService = serviceProvider.GetService<IMyService>();
    }
}