更方便地 Mock Http Response
Intro
在我们的业务代码中往往会有很多调用内部其他 team 或者是第三方的一些服务，在编写单元测试代码时，往往需要 Mock Http Response 来模拟更好可能的返回结果，我封装了一个简单的 Http Handler 来简化 Mock 过程，让基于 HttpClient Http Response 的模拟更为简单。
Sample
首先来看一个简单的使用示例，也是一个测试用例
[Theory]
[InlineData(HttpStatusCode.OK)]
[InlineData(HttpStatusCode.BadRequest)]
[InlineData(HttpStatusCode.Unauthorized)]
[InlineData(HttpStatusCode.Forbidden)]
[InlineData(HttpStatusCode.NotFound)]
[InlineData(HttpStatusCode.InternalServerError)]
public async Task HttpStatusTest(HttpStatusCode httpStatusCode)
{var httpHandler = new MockHttpHandler(req => new HttpResponseMessage(httpStatusCode));using var httpClient = new HttpClient(httpHandler);using var response = await httpClient.GetAsync("http://localhost:32123/api/values");Assert.Equal(httpStatusCode, response.StatusCode);
}如果有需要在测试的过程中修改模拟的行为，可以通过 SetResponseFactory 方法来
[Fact]
public async Task SetResponseFactoryTest()
{var httpHandler = new MockHttpHandler();using var httpClient = new HttpClient(httpHandler);var response = await httpClient.GetAsync("http://localhost:32123/api/values");Assert.Equal(HttpStatusCode.OK, response.StatusCode);httpHandler.SetResponseFactory(req => new HttpResponseMessage(HttpStatusCode.BadRequest));response = await httpClient.GetAsync("http://localhost:32123/api/values");Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
}上面的方式都是直接指定了 response，我们也可以根据请求信息动态地返回 response
[Fact]
public async Task DynamicResponseTest()
{var httpHandler = new MockHttpHandler(req => new HttpResponseMessage(HttpStatusCode.OK){Content = new StringContent(req.Method.Method)});using var httpClient = new HttpClient(httpHandler);var response = await httpClient.GetStringAsync("http://localhost:32123/api/values");Assert.Equal(HttpMethod.Get.Method, response);using var httpResponse = await httpClient.PostAsync("http://localhost:32123/api/values", new StringContent(""));response = await httpResponse.Content.ReadAsStringAsync();Assert.Equal(HttpMethod.Post.Method, response);
}Implement
实现代码很简单，大致如下，根据自定义的逻辑去返回 response 即可
public sealed class MockHttpHandler : HttpMessageHandler
{private Func<HttpRequestMessage, Task<HttpResponseMessage>> _responseFactory;public MockHttpHandler() : this(_ => Task.FromResult(new HttpResponseMessage(HttpStatusCode.OK))){}public MockHttpHandler(Func<HttpRequestMessage, HttpResponseMessage> responseFactory){Guard.NotNull(responseFactory);_responseFactory = req => Task.FromResult(responseFactory(req));}public MockHttpHandler(Func<HttpRequestMessage, Task<HttpResponseMessage>> responseFactory){Guard.NotNull(responseFactory);_responseFactory = responseFactory;}public void SetResponseFactory(Func<HttpRequestMessage, HttpResponseMessage> responseFactory){Guard.NotNull(responseFactory);_responseFactory = req => Task.FromResult(responseFactory(req));}public void SetResponseFactory(Func<HttpRequestMessage, Task<HttpResponseMessage>> responseFactory){Guard.NotNull(responseFactory);_responseFactory = responseFactory;}protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken){return _responseFactory(request);}
}More
在需要模拟 Http API 的响应时，可以考虑使用这种方式，希望对你有帮助
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如果二维码失效也可以加我微信来加群
References
https://github.com/WeihanLi/WeihanLi.Common/blob/dev/src/WeihanLi.Common/Http/MockHttpHandler.cs
https://github.com/WeihanLi/WeihanLi.Common/blob/dev/test/WeihanLi.Common.Test/HttpTest/MockHttpHandlerTest.cs
