public async Task GetAllForMakeShouldReturnAllModelsForMake() { var options = new DbContextOptionsBuilder <NeedForCarsDbContext>() .UseInMemoryDatabase("ModelGetAllDb") .Options; var context = new NeedForCarsDbContext(options); var makesService = new MakesService(context); var modelsService = new ModelsService(context, makesService); var make = new Make { Name = "Make", Description = "Desc" }; await context.Makes.AddAsync(make); await context.SaveChangesAsync(); var model1 = new Model { Name = "Model1", Description = "Desc", MakeId = make.Id }; var model2 = new Model { Name = "Model2", Description = "Desc", MakeId = make.Id }; await context.Models.AddAsync(model1); await context.Models.AddAsync(model2); await context.SaveChangesAsync(); var result = modelsService.GetAllForMake(make.Id).Count(); Assert.Equal(2, result); }