var mockMyRepository = new Mock<IMyRepository>();

mockMyRepository.Setup(repo => repo.GetData("john"))
  .Returns(Task.FromResult("Corrrect"));
mockMyRepository.Setup(repo => repo.GetData("codingblast"))
  .Returns(Task.FromResult("Yeah!"));


var authService = BuildAuthorizationService(services =>
{
    services.AddScoped<IMyRepository>(sp => mockMyRepository.Object);
    services.AddScoped<IAuthorizationHandler, MyCustomHandler>();

    services.AddAuthorization(options =>
    {
        options.AddPolicy("PolicyName", policy => policy.Requirements.Add(new MyCustomRequirement()));
    });
})