Durable Functions 單元測試 (C#)

發行項
06/01/2023

單元測試是現代軟體開發實務中很重要的一部分。單元測試會驗證商務邏輯行為，並且防止在未來引進未注意到的中斷性變更。 Durable Functions 很容易變得複雜，所以引進單元測試有助於避免中斷性變更。下列章節說明如何針對以下三種類型的函式進行單元測試 - 協調流程用戶端、協調器及活動函式。

注意

本文針對使用 C# 為 .NET 內含式工作角色和以 Durable Functions 2.x 為目標所撰寫的 Durable Functions 應用程式，提供單元測試指引。如需版本差異的詳細資訊，請參閱 Durable Functions 版本一文。

必要條件

這篇文章中的範例需要下列概念和架構的知識：

單元測試
長期函式
xUnit - 測試架構
moq - 模擬架構

模擬的基底類別

透過下列介面支援模擬：

這些介面可以搭配 Durable Functions 支援的各種觸發程序和繫結程序使用。執行 Azure Functions 時，函式執行階段會以這些介面的具體實作來執行函式程式碼。針對單元測試，您可以傳入這些介面的模擬版本來測試商務邏輯。

針對觸發程序函式進行單元測試

在本節中，單元測試會驗證下列 HTTP 觸發程序函式對於啟動新協調流程的邏輯。

// 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);
        }
    }
}

單元測試工作會驗證回應承載中提供的 Retry-After 標頭值。因此單元測試會模擬一些 IDurableClient 方法，以確保行為符合預期。

首先，我們會使用模擬架構 (在此案例中為 moq) 來模擬 IDurableClient：

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

注意

雖然您可以直接實作介面作為一個類別來模擬介面，但模擬架構會以各種方式來簡化流程。例如，如果新的方法新增至跨次要發行版本的介面中，moq 不需要像具體實作一般變更任何程式碼。

然後模擬 StartNewAsync 方法以傳回已知的執行個體識別碼。

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

接下來模擬 CreateCheckStatusResponse 以一律傳回空的 HTTP 200 回應。

// 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))
        }
    });

也會模擬 ILogger：

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

現在 Run 方法是從單元測試呼叫：

// 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);

最後一個步驟是比較輸出與預期值：

// 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);

合併所有步驟之後，單元測試會有下列程式碼：

// 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);
        }
    }
}

針對協調器函式進行單元測試

針對協調器函式進行單元測試更加有趣，因為它們通常有更多商務邏輯。

在本節中，單元測試會驗證 E1_HelloSequence 協調器函式的輸出：

// 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}!";
        }
    }
 }

單元測試程式碼會從建立模擬開始：

var durableOrchestrationContextMock = new Mock<IDurableOrchestrationContext>();

然後會模擬活動方法呼叫：

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!");

接下來，單元測試會呼叫 HelloSequence.Run 方法：

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

最後會驗證輸出：

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

合併所有步驟之後，單元測試會有下列程式碼：

// 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]);
        }
    }
}

針對活動函式進行單元測試

可以使用與非持久函式相同的方式來針對活動函式進行單元測試。

在本節中，單元測試會驗證 E1_SayHello 活動函式的行為：

// 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}!";
        }
    }
 }

且單元測試會驗證輸出的格式。單元測試可以直接使用參數類型，或是模擬 IDurableActivityContext 類別：

// 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);
        }
    }
}

下一步

深入了解 xUnit

深入了解 moq