使用 xunit 返回 null 的模拟 HttpClient 包装器

Question

我正在尝试习惯使用 .net Core 进行单元测试。不幸的是，我一直坚持让我的 HttpClient 包装器 return 失败 HttpResponseMessage。

这是我正在努力进行的测试：

[Fact]
public async void TestHttpExceptionOnBadRequest()
{
    using (var stream = new MemoryStream(Encoding.UTF8.GetBytes("Test")))
    {
        var xmlSerializer = new Mock<IXmlSerializer>();
        xmlSerializer.Setup(serializer => serializer.Deserialize(stream)).Returns(new object());

        var httpClient = new Mock<IHttpHandler>();
        httpClient.Setup(client => client.GetAsync("Test"))
            .Returns(Task.FromResult(new HttpResponseMessage(HttpStatusCode.BadRequest)));

        var postcodeLookup = new PostcodeLookupService(xmlSerializer.Object, httpClient.Object, "", "");
        await Assert.ThrowsAsync<HttpRequestException>(async () => await postcodeLookup.SearchAsync("", ""));
    }
}

以下是我的服务代码。问题是 response.EnsureSuccessStatusCode(); return 为空。

public async Task<PostcodeContainer> SearchAsync(string text, string container)
{
    // add the query parameters to the query string
    var query = _baseQueryString + "&text=" + WebUtility.UrlEncode(text);
    query += "&container=" + WebUtility.UrlEncode(container);

    // initiate client & response
    var response = await _httpClient.GetAsync(query);
    response.EnsureSuccessStatusCode();

    return (PostcodeContainer)_serializer.Deserialize(await response.Content.ReadAsStreamAsync());
}

为了完整起见，这里是我的 IHttpHandler 定义，用于模拟目的。

public interface IHttpHandler
{
    HttpResponseMessage Get(string url);
    HttpResponseMessage Post(string url, HttpContent content);
    Task<HttpResponseMessage> GetAsync(string url);
    Task<HttpResponseMessage> PostAsync(string url, HttpContent content);
}

Answer 1

那是因为预期的查询设置与被测方法中生成的不匹配。

// add the query parameters to the query string
var query = _baseQueryString + "&text=" + WebUtility.UrlEncode(text);
query += "&container=" + WebUtility.UrlEncode(container);

这会导致模拟 return null，因为当它收到与 "Test".

不匹配的意外查询时，它不知道该怎么做

因此假设 _baseQueryString 也是一个空字符串，基于示例中的测试，生成的查询可能最终为

&text=&container=

因此，为了按预期执行，模拟应该期望收到什么。还考虑到被测方法预计会在序列化程序执行任何操作之前出错，因此无需将其设置为执行任何操作。只是模拟它并通过模拟。

您还可以通过在设置表达式中使用 It.IsAny<string>() 让客户端期待任何查询。

最后，测试 return Task if performing acync functions

[Fact]
public async Task TestHttpExceptionOnBadRequest() {

    var xmlSerializer = new Mock<IXmlSerializer>();
    xmlSerializer
        .Setup(serializer => serializer.Deserialize(It.IsAny<Stream>()))
        .Returns(new PostcodeContainer());

    var expectedResponse = new HttpResponseMessage(HttpStatusCode.BadRequest);
    var httpClient = new Mock<IHttpHandler>();
    httpClient
        .Setup(client => client.GetAsync(It.IsAny<string>()))
        .ReturnsAsync(expectedResponse);

    var postcodeLookup = new PostcodeLookupService(xmlSerializer.Object, httpClient.Object, "", "");
    await Assert.ThrowsAsync<HttpRequestException>(async () => await postcodeLookup.SearchAsync("", ""));
}

使用 xunit 返回 null 的模拟 HttpClient 包装器

Mocked HttpClient wrapper returning null with xunit

c#

.net

unit-testing

moq

xunit