public async Task AddShippingMethodShouldNotCreateNewMethodIfExist() { var options = new DbContextOptionsBuilder <WHMSDbContext>().UseInMemoryDatabase(databaseName: Guid.NewGuid().ToString()).Options; using var context = new WHMSDbContext(options); var mockInventoryService = new Mock <IInventoryService>(); var service = new ShippingService(context, mockInventoryService.Object); var shippingService = "FedEx"; var carrier = new Carrier { Name = shippingService }; context.Carriers.Add(carrier); var shipping = new ShippingMethod { Carrier = carrier, CarrierId = carrier.Id, Name = shippingService }; context.ShippingMethods.Add(shipping); await context.SaveChangesAsync(); var id = await service.AddShippingMethodAsync(carrier.Id, shippingService); var shippingMethodDB = context.ShippingMethods.FirstOrDefault(); Assert.Equal(shippingService, shippingMethodDB.Name); Assert.Equal(id, shippingMethodDB.Id); }