如何使用 Moq 从 IHttpClientFactory 模拟 HTTPClient 并结合 .NET Core 中的 Polly 策略

Question

我使用 IHttpClientFactory 创建 HTTP 客户端并附加 Polly 策略（需要 Microsoft.Extensions.Http.Polly），如下所示：

using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.DependencyInjection;

IHost host = new HostBuilder()
    .ConfigureServices((hostingContext, services) =>
    {
        services.AddHttpClient("TestClient", client =>
        {
            client.DefaultRequestHeaders.Add("Authorization", $"Bearer {accessToken}");
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
        })
        .AddPolicyHandler(PollyPolicies.HttpResponsePolicies(
            arg1, 
            arg2,
            arg3));
    })
    .Build();

IHttpClientFactory httpClientFactory = host.Services.GetRequiredService<IHttpClientFactory>();

HttpClient httpClient = httpClientFactory.CreateClient("TestClient");

我如何使用 Moq 来模拟这个 HTTP 客户端？

编辑：Mock 意味着能够模拟 HTTP 的请求。应按照定义应用该政策。

Answer 1

正如 stackoverflow 上的许多其他帖子所述，您不会模拟 HTTP 客户端本身，而是模拟 HttpMessageHandler：

Mock<HttpMessageHandler> handlerMock = new Mock<HttpMessageHandler>(MockBehavior.Strict);
handlerMock
    .Protected()
    .Setup<Task<HttpResponseMessage>>(
        "SendAsync",
        ItExpr.IsAny<HttpRequestMessage>(),
        ItExpr.IsAny<CancellationToken>()
    )
    .ReturnsAsync(new HttpResponseMessage()
    {
        StatusCode = HttpStatusCode.OK,
        Content = new StringContent(response)
    });

为了最终拥有一个带有模拟的 HttpMessageHandler 以及 Polly 策略的 HTTP 客户端，您可以执行以下操作：

IServiceCollection services = new ServiceCollection();
services.AddHttpClient("TestClient")
    .AddPolicyHandler(PollyPolicies.HttpResponsePolicies(arg1, arg2, arg3))
    .ConfigurePrimaryHttpMessageHandler(() => handlerMock.Object);

HttpClient httpClient =
    services
        .BuildServiceProvider()
        .GetRequiredService<IHttpClientFactory>()
        .CreateClient("TestClient");