伪造来自测试的 GetAsync 调用

Question

public Fixture()
{
_server = new TestServer(new WebHostBuilder()    
.UseStartup<Startup>()
.ConfigureServices(services =>
{
services.AddScoped<ICarService, CarService>();
}));
Client = _server.CreateClient();
}

从测试中，我正在使用此HttpClient来测试我的API。

using (var response = await _client.GetAsync($"/api/car/{id}"))
{
//...         
}

问题是我想在课堂上伪造GetAsync(int id)方法的结果CarService。

所以我尝试了

var myCarObject = ... omitted for clarity
var myCarMockService = new Mock<ICarService>();
myCarMockService.Setup(x => x.GetAsync(It.IsAny<int>())).Returns(Task.FromResult(myCarObject));

我不知道这是正确的方法，但如果是，我该如何注射它 放入Fixture类中，以便CarService可以使用它。

public class CarService: ICarService {
private readonly CarDbContext _carDbContext;
public CarService(CarDbContext carDbContext)
{
_carDbContext = carDbContext;
}
public async Task<Car> GetAsync(int id)
{
return await _carDbContext.Cars.FindAsync(id);
}
}

更新：

private readonly ICarService _carService;
public CarController(ICarService carService)
{
_carService = carService;
}
public async Task<IActionResult> Get([FromRoute] int id)
{
var car = await _carService.GetAsync(id);
}

更新 2：

public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
services.AddDbContext<CarDbContext>(options => { options.UseSqlServer(Configuration.GetConnectionString("Db")); });
services.AddTransient<ICarService, CarService>();
}
}
public class CarService : ICarService
{
private readonly CarDbContext _carDbContext;
public ContactService(CarDbContext carDbContext)
{
_carDbContext= carDbContext;
}
public async Task<Owner> GetAsync(int ownerId)
{
var owner = await _carDbContext.Owners.FindAsync(ownerId);
return owner.Car;            
}
}

更新 3：

private readonly TestServer _server;
public Fixture()
{
var dbContextOptions = new DbContextOptionsBuilder<CarDbContext>()
.UseInMemoryDatabase(Guid.NewGuid().ToString())
.Options;
var mockContext = new Mock<CarDbContext>(dbContextOptions);
var mockOwnerSet = new Mock<DbSet<Owner>>();
var mockCarSet = new Mock<DbSet<Car>>();
mockContext.Setup(m => m.Owners).Returns(mockOwnerSet.Object);
mockContext.Setup(m => m.Cars).Returns(mockCarSet.Object);          
var carService = new CarService(mockContext.Object);
_server = new TestServer(new WebHostBuilder()
.ConfigureAppConfiguration((context, conf) =>
{
conf.AddJsonFile(@Directory.GetCurrentDirectory() + "../appsettings.json");
}).UseStartup<Startup>()
.ConfigureServices(services =>
{
services.AddDbContext<CarDbContext>(options => options.UseInMemoryDatabase("Test"));
services.AddScoped<ICarService>(_ => carService);
})
);
Client = _server.CreateClient();    
}   

Answer 1

配置测试服务器以使用模拟服务

public Fixture() {
Car myCarObject = //... omitted for brevity
var myCarMockService = new Mock<ICarService>();
myCarMockService
.Setup(x => x.GetAsync(It.IsAny<int>()))
.ReturnsAsync(myCarObject);
_server = new TestServer(new WebHostBuilder()
.UseStartup<Startup>()
.ConfigureTestServices(services => {
var serviceDescriptor = services.FirstOrDefault(descriptor => descriptor.ServiceType == typeof(ICarService));
if (serviceDescriptor != null) services.Remove(serviceDescriptor);
services.AddTransient<ICarService>(_ => myCarMockService.Object); // <-- NOTE
})
);
Client = _server.CreateClient();
}

这样，当进行调用时，模拟服务将按预期注入。