InMemoryDBTesting.cs

 public void ConfigureServices(IServiceCollection services)
        {
            if (CurrentEnvironment.IsDevelopment()) // Here is where we check
            {
                services.AddDbContext<AppDbContext>(
                    options => options.UseInMemoryDatabase()); // And we ask it to use the InMemoryDatabase Option
            }
            else
            {
                services.AddDbContext<AppDbContext>(
                options => options.UseSqlServer(
                    Configuration.GetConnectionString("DefaultConnection")));
            }
            

            services.AddScoped<ICreditCardApplicationRepository, 
                               EntityFrameworkCreditCardApplicationRepository>();

            services.AddMvc();            
        }