如何在 .NET Core 中模拟/存根 HttpRequestMessage？

Question

我有一个要从 Azure Functions v1 移植到 v2 的函数，作为其中的一部分，我在更新创建存根 HttpRequestMessage 的单元测试时遇到了问题。这是适用于 Functions v1 的代码，针对 .NET Framework 4.7

public class FunctionExample
{
    [FunctionName(nameof(SomeFunction))]
    public static async Task<HttpResponseMessage> SomeFunction
    (
        [HttpTrigger(AuthorizationLevel.Anonymous, "post", Route = "SomeFunction")]
        HttpRequestMessage request
    )
    {
        var body = await request.Content.ReadAsStringAsync();
        if (string.IsNullOrEmpty(body))
        {
            return request.CreateResponse(HttpStatusCode.BadRequest, "Bad job");
        }
        else
        {
            return request.CreateResponse(HttpStatusCode.OK, "Good job");
        }
    }
}

还有我的测试代码

public class FunctionExampleTests
{
    [Test]
    public async Task TestSomeFunction()
    {
        var request = new HttpRequestMessage
        {
            Method = HttpMethod.Post,
            RequestUri = new Uri("http://localhost/"),
            Content = new StringContent("", Encoding.UTF8, "application/json")
        };

        request.Properties.Add(HttpPropertyKeys.HttpConfigurationKey,
            new HttpConfiguration());

        var response = await FunctionExample.SomeFunction(request);

        var content = await response.Content.ReadAsStringAsync();

        Assert.That(response.StatusCode, Is.EqualTo(HttpStatusCode.BadRequest));
        Assert.That(content, Is.EqualTo("\"Bad job\""));
    }
}

移植到v2后，我的函数项目csproj文件是这样的。唯一的区别是我不再以完整框架为目标，并且添加了AzureFunctionsVersion 节点。

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>netstandard2.0</TargetFramework>
    <AzureFunctionsVersion>v2</AzureFunctionsVersion>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.NET.Sdk.Functions" Version="1.0.24" />
  </ItemGroup>
</Project>

这是我重定向到 .NET Core 2.0 后测试项目的 csproj

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>netcoreapp2.0</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="nunit" Version="3.11.0" />
    <PackageReference Include="NUnit3TestAdapter" Version="3.13.0" />
    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.9.0" />
  </ItemGroup>
  <ItemGroup>
    <ProjectReference Include="..\FunctionExample\FunctionExample.csproj" />
  </ItemGroup>
</Project>

以前，我使用this question 的答案正确地存根 HttpRequestMessage，但这似乎不再起作用。

当我尝试编译它时，我得到以下编译错误

Error   CS0246  The type or namespace name 'HttpConfiguration' could not be found (are you missing a using directive or an assembly reference?)
Error   CS0103  The name 'HttpPropertyKeys' does not exist in the current context

所以如果我只是删除该行，希望不再需要修复

request.Properties.Add(HttpPropertyKeys.HttpConfigurationKey, new HttpConfiguration());

相反，我收到此错误消息

System.InvalidOperationException : HttpRequestMessage 实例未正确初始化。使用 HttpRequestMessageHttpContextExtensions.GetHttpRequestMessage 为当前请求创建一个 HttpRequestMessage。

尝试按照错误消息的指示对我来说没有结果，我尝试设置 HttpContext like was done in this question

request.Properties.Add(nameof(HttpContext), new DefaultHttpContext());

但这给了我一个不同的错误（与问题相同）

System.ArgumentNullException : 值不能为空。

参数名称：提供者

Answer 1

Azure Functions 在某种程度上基于 ASP.NET MVC WebApi，它对 .NET Core 进行了一些更改。例如，HttpConfiguration 在任何面向 .NET Core/Standard 的包中似乎都不可用。为了解决这个问题，我必须在我的 test 项目中安装几个包，即Microsoft.AspNetCore.Mvc 用于AddMvc() 和Microsoft.AspNetCore.Mvc.WebApiCompatShim 用于.AddWebApiConventions()，其中：

在 ASP.NET Core MVC 中提供与 ASP.NET Web API 2 的兼容性，以简化现有 Web API 实现的迁移

所以我将这些添加到我的测试项目中

<PackageReference Include="Microsoft.AspNetCore.Mvc" Version="2.2.0" />
<PackageReference Include="Microsoft.AspNetCore.Mvc.WebApiCompatShim" Version="2.2.0" />

现在我的测试项目是这样的

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>netcoreapp2.0</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="nunit" Version="3.11.0" />
    <PackageReference Include="Microsoft.AspNetCore.Mvc" Version="2.2.0" />
    <PackageReference Include="Microsoft.AspNetCore.Mvc.WebApiCompatShim" Version="2.2.0" />
    <PackageReference Include="NUnit3TestAdapter" Version="3.13.0" />
    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.9.0" />
  </ItemGroup>
  <ItemGroup>
    <ProjectReference Include="..\FunctionExampleFunction\FunctionExampleFunction.csproj" />
  </ItemGroup>
</Project>

为了模拟 ArgumentNullException 暗示的服务缺失（在这种情况下我认为是 MediaTypeFormatters），我必须从本质上引导 MVC 以正确初始化 HttpContext。

[Test]
public async Task TestSomeFunction()
{
    var request = new HttpRequestMessage
    {
        Method = HttpMethod.Post,
        RequestUri = new Uri("http://localhost/"),
        Content = new StringContent("", Encoding.UTF8, "application/json")
    };

    var services = new ServiceCollection()
        .AddMvc()
        .AddWebApiConventions()
        .Services
        .BuildServiceProvider();

    request.Properties.Add(nameof(HttpContext), new DefaultHttpContext
    {
        RequestServices = services
    });

    var response = await FunctionExample.SomeFunction(request);

    var content = await response.Content.ReadAsStringAsync();

    Assert.That(response.StatusCode, Is.EqualTo(HttpStatusCode.BadRequest));
    Assert.That(content, Is.EqualTo("\"Bad job\""));
}

这使得测试可以编译、运行和通过。