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Durable Functions 单元测试 (C#)

项目
06/01/2023

单元测试是现代软件开发实践中的重要组成部分。单元测试可验证业务逻辑行为，防止将来引入无法察觉的中断性变更。 Durable Functions 的复杂性很容易增大，因此，引入单元测试有助于避免中断性变更。以下部分介绍如何对三种函数类型执行单元测试 - 业务流程客户端、业务流程协调程序和活动函数。

注意

针对 .NET 进程内辅助角色和面向 Durable Functions 2.x 的 Durable Functions 应用（以 C# 编写），本文提供单元测试指南。有关版本之间差异的详细信息，请参阅 Durable Functions 版本一文。

先决条件

学习本文中的示例需要了解以下概念和框架：

单元测试
Durable Functions
xUnit - 测试框架
moq - 模拟框架

用于模拟的基类

通过以下接口支持模拟：

这些接口可以与 Durable Functions 支持的各种触发器和绑定配合使用。执行 Azure Functions 时，函数运行时会运行包含这些接口的具体实现的函数代码。对于单元测试，可以传递这些接口的模拟版本来测试业务逻辑。

对触发器函数进行单元测试

在此部分，单元测试将会验证用于启动新业务流程的以下 HTTP 触发器函数的逻辑。

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the MIT License. See LICENSE in the project root for license information.

using System.Net.Http;
using System.Threading.Tasks;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.DurableTask;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.Extensions.Logging;

namespace VSSample
{
    public static class HttpStart
    {
        [FunctionName("HttpStart")]
        public static async Task<HttpResponseMessage> Run(
            [HttpTrigger(AuthorizationLevel.Function, methods: "post", Route = "orchestrators/{functionName}")] HttpRequestMessage req,
            [DurableClient] IDurableClient starter,
            string functionName,
            ILogger log)
        {
            // Function input comes from the request content.
            object eventData = await req.Content.ReadAsAsync<object>();
            string instanceId = await starter.StartNewAsync(functionName, eventData);

            log.LogInformation($"Started orchestration with ID = '{instanceId}'.");

            return starter.CreateCheckStatusResponse(req, instanceId);
        }
    }
}

单元测试任务是验证响应有效负载中提供的 Retry-After 标头的值。因此，单元测试将模拟某些 IDurableClient 方法，以确保行为可预测。

首先，使用模拟框架（在此示例中为 moq）来模拟 IDurableClient：

// Mock IDurableClient
var durableClientMock = new Mock<IDurableClient>();

注意

尽管可以通过直接将接口实现为类来模拟接口，但模拟框架从各方面简化了该过程。例如，如果在多个次要版本中向接口添加了新的方法，则 moq 不需要任何代码更改，这与具体的实现不同。

然后，模拟 StartNewAsync 方法来返回已知的实例 ID。

// Mock StartNewAsync method
durableClientMock.
    Setup(x => x.StartNewAsync(functionName, It.IsAny<object>())).
    ReturnsAsync(instanceId);

接下来模拟 CreateCheckStatusResponse，以便始终返回空白的 HTTP 200 响应。

// Mock CreateCheckStatusResponse method
durableClientMock
    // Notice that even though the HttpStart function does not call IDurableClient.CreateCheckStatusResponse() 
    // with the optional parameter returnInternalServerErrorOnFailure, moq requires the method to be set up
    // with each of the optional parameters provided. Simply use It.IsAny<> for each optional parameter
    .Setup(x => x.CreateCheckStatusResponse(It.IsAny<HttpRequestMessage>(), instanceId, returnInternalServerErrorOnFailure: It.IsAny<bool>()))
    .Returns(new HttpResponseMessage
    {
        StatusCode = HttpStatusCode.OK,
        Content = new StringContent(string.Empty),
        Headers =
        {
            RetryAfter = new RetryConditionHeaderValue(TimeSpan.FromSeconds(10))
        }
    });

另外还要模拟 ILogger：

// Mock ILogger
var loggerMock = new Mock<ILogger>();

现在，从单元测试调用 Run 方法：

// Call Orchestration trigger function
var result = await HttpStart.Run(
    new HttpRequestMessage()
    {
        Content = new StringContent("{}", Encoding.UTF8, "application/json"),
        RequestUri = new Uri("http://localhost:7071/orchestrators/E1_HelloSequence"),
    },
    durableClientMock.Object,
    functionName,
    loggerMock.Object);

最后一步是将输出与预期值进行比较：

// Validate that output is not null
Assert.NotNull(result.Headers.RetryAfter);

// Validate output's Retry-After header value
Assert.Equal(TimeSpan.FromSeconds(10), result.Headers.RetryAfter.Delta);

合并所有步骤后，单元测试将获得以下代码：

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the MIT License. See LICENSE in the project root for license information.

namespace VSSample.Tests
{
    using System;
    using System.Net;
    using System.Net.Http;
    using System.Text;
    using System.Threading.Tasks;
    using System.Net.Http.Headers;
    using Microsoft.Azure.WebJobs.Extensions.DurableTask;
    using Microsoft.Extensions.Logging;
    using Moq;
    using Xunit;

    public class HttpStartTests
    {
        [Fact]
        public async Task HttpStart_returns_retryafter_header()
        {
            // Define constants
            const string functionName = "SampleFunction";
            const string instanceId = "7E467BDB-213F-407A-B86A-1954053D3C24";

            // Mock TraceWriter
            var loggerMock = new Mock<ILogger>();

            // Mock DurableOrchestrationClientBase
            var clientMock = new Mock<IDurableClient>();

            // Mock StartNewAsync method
            clientMock.
                Setup(x => x.StartNewAsync(functionName, It.IsAny<string>(), It.IsAny<object>())).
                ReturnsAsync(instanceId);

            // Mock CreateCheckStatusResponse method
            clientMock
                .Setup(x => x.CreateCheckStatusResponse(It.IsAny<HttpRequestMessage>(), instanceId, false))
                .Returns(new HttpResponseMessage
                {
                    StatusCode = HttpStatusCode.OK,
                    Content = new StringContent(string.Empty),
                    Headers =
                    {
                        RetryAfter = new RetryConditionHeaderValue(TimeSpan.FromSeconds(10))
                    }
                });

            // Call Orchestration trigger function
            var result = await HttpStart.Run(
                new HttpRequestMessage()
                {
                    Content = new StringContent("{}", Encoding.UTF8, "application/json"),
                    RequestUri = new Uri("http://localhost:7071/orchestrators/E1_HelloSequence"),
                },
                clientMock.Object,
                functionName,
                loggerMock.Object);

            // Validate that output is not null
            Assert.NotNull(result.Headers.RetryAfter);

            // Validate output's Retry-After header value
            Assert.Equal(TimeSpan.FromSeconds(10), result.Headers.RetryAfter.Delta);
        }
    }
}

对业务流程协调程序函数进行单元测试

业务流程协调程序包含的业务逻辑通常要多得多，因此，它们的单元测试更有趣。

在本部分，单元测试将验证 E1_HelloSequence 业务流程协调程序函数的输出：

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the MIT License. See LICENSE in the project root for license information.

using System.Collections.Generic;
using System.Threading.Tasks;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.DurableTask;

namespace VSSample
{
    public static class HelloSequence
    {
        [FunctionName("E1_HelloSequence")]
        public static async Task<List<string>> Run(
            [OrchestrationTrigger] IDurableOrchestrationContext context)
        {
            var outputs = new List<string>();

            outputs.Add(await context.CallActivityAsync<string>("E1_SayHello", "Tokyo"));
            outputs.Add(await context.CallActivityAsync<string>("E1_SayHello", "Seattle"));
            outputs.Add(await context.CallActivityAsync<string>("E1_SayHello_DirectInput", "London"));

            // returns ["Hello Tokyo!", "Hello Seattle!", "Hello London!"]
            return outputs;
        }

        [FunctionName("E1_SayHello")]
        public static string SayHello([ActivityTrigger] IDurableActivityContext context)
        {
            string name = context.GetInput<string>();
            return $"Hello {name}!";
        }

        [FunctionName("E1_SayHello_DirectInput")]
        public static string SayHelloDirectInput([ActivityTrigger] string name)
        {
            return $"Hello {name}!";
        }
    }
 }

单元测试代码首先会创建模拟：

var durableOrchestrationContextMock = new Mock<IDurableOrchestrationContext>();

然后模拟活动方法调用：

durableOrchestrationContextMock.Setup(x => x.CallActivityAsync<string>("E1_SayHello", "Tokyo")).ReturnsAsync("Hello Tokyo!");
durableOrchestrationContextMock.Setup(x => x.CallActivityAsync<string>("E1_SayHello", "Seattle")).ReturnsAsync("Hello Seattle!");
durableOrchestrationContextMock.Setup(x => x.CallActivityAsync<string>("E1_SayHello", "London")).ReturnsAsync("Hello London!");

接下来，单元测试调用 HelloSequence.Run 方法：

var result = await HelloSequence.Run(durableOrchestrationContextMock.Object);

最后验证输出：

Assert.Equal(3, result.Count);
Assert.Equal("Hello Tokyo!", result[0]);
Assert.Equal("Hello Seattle!", result[1]);
Assert.Equal("Hello London!", result[2]);

合并所有步骤后，单元测试将获得以下代码：

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the MIT License. See LICENSE in the project root for license information.

namespace VSSample.Tests
{
    using System.Threading.Tasks;
    using Microsoft.Azure.WebJobs.Extensions.DurableTask;
    using Moq;
    using Xunit;

    public class HelloSequenceTests
    {
        [Fact]
        public async Task Run_returns_multiple_greetings()
        {
            var mockContext = new Mock<IDurableOrchestrationContext>();
            mockContext.Setup(x => x.CallActivityAsync<string>("E1_SayHello", "Tokyo")).ReturnsAsync("Hello Tokyo!");
            mockContext.Setup(x => x.CallActivityAsync<string>("E1_SayHello", "Seattle")).ReturnsAsync("Hello Seattle!");
            mockContext.Setup(x => x.CallActivityAsync<string>("E1_SayHello_DirectInput", "London")).ReturnsAsync("Hello London!");

            var result = await HelloSequence.Run(mockContext.Object);

            Assert.Equal(3, result.Count);
            Assert.Equal("Hello Tokyo!", result[0]);
            Assert.Equal("Hello Seattle!", result[1]);
            Assert.Equal("Hello London!", result[2]);
        }
    }
}

对活动函数进行单元测试

可以像测试非持久性函数一样对活动函数进行单元测试。

在本部分，单元测试将验证 E1_SayHello 活动函数的行为：

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the MIT License. See LICENSE in the project root for license information.

using System.Collections.Generic;
using System.Threading.Tasks;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.DurableTask;

namespace VSSample
{
    public static class HelloSequence
    {
        [FunctionName("E1_HelloSequence")]
        public static async Task<List<string>> Run(
            [OrchestrationTrigger] IDurableOrchestrationContext context)
        {
            var outputs = new List<string>();

            outputs.Add(await context.CallActivityAsync<string>("E1_SayHello", "Tokyo"));
            outputs.Add(await context.CallActivityAsync<string>("E1_SayHello", "Seattle"));
            outputs.Add(await context.CallActivityAsync<string>("E1_SayHello_DirectInput", "London"));

            // returns ["Hello Tokyo!", "Hello Seattle!", "Hello London!"]
            return outputs;
        }

        [FunctionName("E1_SayHello")]
        public static string SayHello([ActivityTrigger] IDurableActivityContext context)
        {
            string name = context.GetInput<string>();
            return $"Hello {name}!";
        }

        [FunctionName("E1_SayHello_DirectInput")]
        public static string SayHelloDirectInput([ActivityTrigger] string name)
        {
            return $"Hello {name}!";
        }
    }
 }

另外，单元测试将验证输出格式。单元测试可以直接使用参数类型，也可以模拟 IDurableActivityContext 类：

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the MIT License. See LICENSE in the project root for license information.

namespace VSSample.Tests
{
    using Microsoft.Azure.WebJobs.Extensions.DurableTask;
    using Xunit;
    using Moq;

    public class HelloSequenceActivityTests
    {
        [Fact]
        public void SayHello_returns_greeting()
        {
            var durableActivityContextMock = new Mock<IDurableActivityContext>();
            durableActivityContextMock.Setup(x => x.GetInput<string>()).Returns("John");
            var result = HelloSequence.SayHello(durableActivityContextMock.Object);
            Assert.Equal("Hello John!", result);
        }

        [Fact]
        public void SayHello_returns_greeting_direct_input()
        {
            var result = HelloSequence.SayHelloDirectInput("John");
            Assert.Equal("Hello John!", result);
        }
    }
}

后续步骤

详细了解 xUnit

详细了解 moq

通过