我有一些问题，试图包装我的代码在单元测试中使用。问题在于。我有接口IHttpHandler:
public interface IHttpHandler
{
HttpClient client { get; }
}
使用它的类HttpHandler:
public class HttpHandler : IHttpHandler
{
public HttpClient client
{
get
{
return new HttpClient();
}
}
}
然后是Connection类，它使用simpleIOC注入客户端实现:
public class Connection
{
private IHttpHandler _httpClient;
public Connection(IHttpHandler httpClient)
{
_httpClient = httpClient;
}
}
然后我有一个单元测试项目，它有这个类:
private IHttpHandler _httpClient;
[TestMethod]
public void TestMockConnection()
{
var client = new Connection(_httpClient);
client.doSomething();
// Here I want to somehow create a mock instance of the http client
// Instead of the real one. How Should I approach this?
}
现在很明显，我将在Connection类中拥有从后端检索数据(JSON)的方法。但是，我想为这个类编写单元测试，显然我不想针对真正的后端编写测试，而是一个模拟的后端。我试着给这个问题一个好的答案，但没有成功。我以前可以用Moq来模拟，但从来没有在HttpClient这样的东西上使用过。我应该如何处理这个问题?
我同意其他一些回答，最好的方法是在HttpClient内部模拟HttpMessageHandler，而不是包装HttpClient。这个答案是唯一的，因为它仍然注入HttpClient，允许它成为一个单例或者使用依赖注入进行管理。
HttpClient打算被实例化一次，并在整个过程中被重用
应用程序的生命周期。
(来源)。
模拟HttpMessageHandler可能有点棘手，因为SendAsync是受保护的。下面是一个使用xunit和Moq的完整示例。
using System;
using System.Net;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;
using Moq;
using Moq.Protected;
using Xunit;
// Use nuget to install xunit and Moq
namespace MockHttpClient {
class Program {
static void Main(string[] args) {
var analyzer = new SiteAnalyzer(Client);
var size = analyzer.GetContentSize("http://microsoft.com").Result;
Console.WriteLine($"Size: {size}");
}
private static readonly HttpClient Client = new HttpClient(); // Singleton
}
public class SiteAnalyzer {
public SiteAnalyzer(HttpClient httpClient) {
_httpClient = httpClient;
}
public async Task<int> GetContentSize(string uri)
{
var response = await _httpClient.GetAsync( uri );
var content = await response.Content.ReadAsStringAsync();
return content.Length;
}
private readonly HttpClient _httpClient;
}
public class SiteAnalyzerTests {
[Fact]
public async void GetContentSizeReturnsCorrectLength() {
// Arrange
const string testContent = "test content";
var mockMessageHandler = new Mock<HttpMessageHandler>();
mockMessageHandler.Protected()
.Setup<Task<HttpResponseMessage>>("SendAsync", ItExpr.IsAny<HttpRequestMessage>(), ItExpr.IsAny<CancellationToken>())
.ReturnsAsync(new HttpResponseMessage {
StatusCode = HttpStatusCode.OK,
Content = new StringContent(testContent)
});
var underTest = new SiteAnalyzer(new HttpClient(mockMessageHandler.Object));
// Act
var result = await underTest.GetContentSize("http://anyurl");
// Assert
Assert.Equal(testContent.Length, result);
}
}
}
这里有一个简单的解决方法，对我来说很有效。
使用moq mock库。
// ARRANGE
var handlerMock = new Mock<HttpMessageHandler>(MockBehavior.Strict);
handlerMock
.Protected()
// Setup the PROTECTED method to mock
.Setup<Task<HttpResponseMessage>>(
"SendAsync",
ItExpr.IsAny<HttpRequestMessage>(),
ItExpr.IsAny<CancellationToken>()
)
// prepare the expected response of the mocked http call
.ReturnsAsync(new HttpResponseMessage()
{
StatusCode = HttpStatusCode.OK,
Content = new StringContent("[{'id':1,'value':'1'}]"),
})
.Verifiable();
// use real http client with mocked handler here
var httpClient = new HttpClient(handlerMock.Object)
{
BaseAddress = new Uri("http://test.com/"),
};
var subjectUnderTest = new MyTestClass(httpClient);
// ACT
var result = await subjectUnderTest
.GetSomethingRemoteAsync('api/test/whatever');
// ASSERT
result.Should().NotBeNull(); // this is fluent assertions here...
result.Id.Should().Be(1);
// also check the 'http' call was like we expected it
var expectedUri = new Uri("http://test.com/api/test/whatever");
handlerMock.Protected().Verify(
"SendAsync",
Times.Exactly(1), // we expected a single external request
ItExpr.Is<HttpRequestMessage>(req =>
req.Method == HttpMethod.Get // we expected a GET request
&& req.RequestUri == expectedUri // to this uri
),
ItExpr.IsAny<CancellationToken>()
);
来源:https://gingter.org/2018/07/26/how-to-mock-httpclient-in-your-net-c-unit-tests/
也许在您当前的项目中会有一些代码需要更改，但对于新项目，您绝对应该考虑使用Flurl。
https://flurl.dev
它是一个。net的HTTP客户端库，具有一个流畅的接口，特别支持使用它来发出HTTP请求的代码的可测试性。
网站上有很多代码示例，但简单地说，你在代码中是这样使用的。
添加用途。
using Flurl;
using Flurl.Http;
发送get请求并读取响应。
public async Task SendGetRequest()
{
var response = await "https://example.com".GetAsync();
// ...
}
在单元测试中，Flurl充当一个模拟，可以将其配置为所需的行为，还可以验证所执行的调用。
using (var httpTest = new HttpTest())
{
// Arrange
httpTest.RespondWith("OK", 200);
// Act
await sut.SendGetRequest();
// Assert
httpTest.ShouldHaveCalled("https://example.com")
.WithVerb(HttpMethod.Get);
}
你所需要的只是传递给HttpClient ctor的HttpMessageHandler类的测试版本。主要的一点是，您的测试HttpMessageHandler类将有一个HttpRequestHandler委托，调用者可以设置它，并简单地以他们想要的方式处理HttpRequest。
public class FakeHttpMessageHandler : HttpMessageHandler
{
public Func<HttpRequestMessage, CancellationToken, HttpResponseMessage> HttpRequestHandler { get; set; } =
(r, c) =>
new HttpResponseMessage
{
ReasonPhrase = r.RequestUri.AbsoluteUri,
StatusCode = HttpStatusCode.OK
};
protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
return Task.FromResult(HttpRequestHandler(request, cancellationToken));
}
}
您可以使用该类的实例来创建具体的HttpClient实例。通过HttpRequestHandler委托，你可以完全控制HttpClient发出的http请求。
