在 .NET 5 中测试 Azure 函数

Question

我已经开始开发 Azure Functions，现在我想创建我的第一个 unit/integration 测试，但我完全卡住了。虽然我有一个带有 HTTP 触发器和 HTTP 和存储队列输出的非常简单的函数，但测试它似乎复杂得可笑。

代码（简体）：

public class MyOutput
{
    [QueueOutput("my-queue-name", Connection = "my-connection")]
    public string QueueMessage { get; set; }

    public HttpResponseData HttpResponse { get; set; }
}

public static class MyFunction
{
    [Function(nameof(MyFunction))]
    public static async Task<MyOutput> Run(
        [HttpTrigger(AuthorizationLevel.Function, "POST")] HttpRequestData req,
        FunctionContext executionContext)
    {
        var logger = executionContext.GetLogger(nameof(MyFunction));
        logger.LogInformation("Received {Bytes} bytes", req.Body.Length);
        //implementation
    }
}

现在我希望构建这样的测试：

public async Task Test()
{
    var response = await MyFunction.Run(..., ...);
    Assert.IsNotNull(response);
}

在互联网上寻找了好几个小时后，我仍然没有找到模拟 HttpRequestData 和 FunctionContext 的方法。我还通过设置服务器来寻找完整的集成测试，但这看起来真的很复杂。我最后得到的唯一结果是：https://github.com/Azure/azure-functions-dotnet-worker/blob/72b9d17a485eda1e6e3626a9472948be1152ab7d/test/E2ETests/E2ETests/HttpEndToEndTests.cs

有没有人有在 .NET 5 中测试 Azure Functions 的经验，谁能给我一个正确的方向？是否有关于如何在 dotnet-isolated 中测试 Azure 函数的好文章或示例？

Answer 1

解决方案 1

我终于可以嘲笑整件事了。绝对不是我最好的作品，可以使用一些重构，但至少我得到了一个工作原型：

var serviceCollection = new ServiceCollection();
serviceCollection.AddScoped<ILoggerFactory, LoggerFactory>();
var serviceProvider = serviceCollection.BuildServiceProvider();

var context = new Mock<FunctionContext>();
context.SetupProperty(c => c.InstanceServices, serviceProvider);

var byteArray = Encoding.ASCII.GetBytes("test");
var bodyStream = new MemoryStream(byteArray);

var request = new Mock<HttpRequestData>(context.Object);
request.Setup(r => r.Body).Returns(bodyStream);
request.Setup(r => r.CreateResponse()).Returns(() =>
{
    var response = new Mock<HttpResponseData>(context.Object);
    response.SetupProperty(r => r.Headers, new HttpHeadersCollection());
    response.SetupProperty(r => r.StatusCode);
    response.SetupProperty(r => r.Body, new MemoryStream());
    return response.Object;
});

var result = await MyFunction.Run(request.Object, context.Object);
result.HttpResponse.Body.Seek(0, SeekOrigin.Begin);
var reader = new StreamReader(result.HttpResponse.Body);
var responseBody = await reader.ReadToEndAsync();

Assert.IsNotNull(result);
Assert.AreEqual(HttpStatusCode.OK, result.HttpResponse.StatusCode);
Assert.AreEqual("Hello test", responseBody);

解决方案 2

我通过依赖注入添加了 Logger，并为 HttpRequestData 和 HttpResponseData 创建了我自己的实现。这样更容易重用并使测试本身更干净。

public class FakeHttpRequestData : HttpRequestData
{
        public FakeHttpRequestData(FunctionContext functionContext, Uri url, Stream body = null) : base(functionContext)
    {
        Url = url;
        Body = body ?? new MemoryStream();
    }

    public override Stream Body { get; } = new MemoryStream();

    public override HttpHeadersCollection Headers { get; } = new HttpHeadersCollection();

    public override IReadOnlyCollection<IHttpCookie> Cookies { get; }

    public override Uri Url { get; }

    public override IEnumerable<ClaimsIdentity> Identities { get; }

    public override string Method { get; }

    public override HttpResponseData CreateResponse()
    {
        return new FakeHttpResponseData(FunctionContext);
    }
}

public class FakeHttpResponseData : HttpResponseData
{
    public FakeHttpResponseData(FunctionContext functionContext) : base(functionContext)
    {
    }

    public override HttpStatusCode StatusCode { get; set; }
    public override HttpHeadersCollection Headers { get; set; } = new HttpHeadersCollection();
    public override Stream Body { get; set; } = new MemoryStream();
    public override HttpCookies Cookies { get; }
}

现在测试看起来像这样：

// Arrange
var body = new MemoryStream(Encoding.ASCII.GetBytes("{ \"test\": true }"))
var context = new Mock<FunctionContext>();
var request = new FakeHttpRequestData(
                context.Object, 
                new Uri("https://whosebug.com"), 
                body);

// Act
var function = new MyFunction(new NullLogger<MyFunction>());
var result = await function.Run(request);
result.HttpResponse.Body.Position = 0;

// Assert
var reader = new StreamReader(result.HttpResponse.Body);
var responseBody = await reader.ReadToEndAsync();
Assert.IsNotNull(result);
Assert.AreEqual(HttpStatusCode.OK, result.HttpResponse.StatusCode);
Assert.AreEqual("Hello test", responseBody);

Answer 2

调用函数的运行方法与其说是集成测试，不如说是一个单元。想想你设置的一些中间件或认证，在直接调用Function时不会运行。

但是，目前看来，还没有优雅的进程内方法来对基于 .NET 5 的 Azure Isolated Functions 进行集成测试。请参阅：https://github.com/Azure/azure-functions-dotnet-worker/issues/541 and https://github.com/Azure/azure-functions-dotnet-worker/issues/281

我通过在本地启动 Azure 函数主机“func”、托管我的函数然后使用测试本身的普通 HttpClient 取得了一些成功。在此之前，您可以设置您不想模拟的其他依赖项，例如 Azurite 和一些 blob 数据。

Answer 3

为了补充您一直在做的事情，我试图模拟 GetLogger() 以便我可以注入 ILogger；不幸的是，GetLogger() 是一个扩展（静态的）所以它不能通过反射来模拟。我现在正在模拟 GetLogger() 扩展（.Net source code）使用的字段。

看起来像这样：

using Mock;
using Microsoft.Extensions.DependencyInjection;

public static FunctionContext CreateFunctionContext(ILogger logger = null)
    {
        
        logger = logger ?? CreateNullLogger();

        var LoggerFactory = new Mock<ILoggerFactory>();
        LoggerFactory.Setup(p => p.CreateLogger(It.IsAny<string>())).Returns(logger);

        var InstanceServices = new Mock<IServiceProvider>();
        InstanceServices.Setup(p => p.GetService(It.IsAny<Type>())).Returns(LoggerFactory.Object);

        var context = new Mock<FunctionContext>();
        context.Setup(p => p.InstanceServices).Returns(InstanceServices.Object);
        return context.Object;

    }

Answer 4

您可以模拟上下文并仅提供您将从中使用的内容。在这里，您有一种使用 NSubstitute 获取 ILogger 的方法，您可以根据需要进行自定义：

[TestClass]
public class FunctionTest
{
    private static readonly FunctionContext _context = Substitute.For<FunctionContext>();
    private static readonly ILogger _logger = Substitute.For<ILogger>();

    [ClassInitialize]
    public static void ClassSetupAsync(TestContext _)
    {
        // create a mock log factory that returns a mocked logger
        var logFactory = Substitute.For<ILoggerFactory>();
        logFactory
            .CreateLogger(Arg.Any<string>())
            .Returns(_logger);

        // create a mock service provider that knows only about logs
        var services = Substitute.For<IServiceProvider>();
        services
            .GetService(Arg.Any<Type>())
            .Returns(logFactory);

        // use the mocked service provider in the mocked context
        // you can pass this context to your Azure Function
        _context
            .InstanceServices
            .Returns(services);
    }
}

在 .NET 5 中测试 Azure 函数

Testing an Azure Function in .NET 5

.net

azure

azure-functions

解决方案 1

解决方案 2