3

我有以下课程，我希望为其创建单元测试：

    public class ServiceBusClient {
        private readonly IMessageReceiver messageReceiver;
        private readonly int maximumMessages;

        public ServiceBusClient(IMessageReceiver messageReceiver, int maximumMessages) {
            this.messageReceiver = messageReceiver;
            this.maximumMessages = maximumMessages;
        }

        public async Task<List<EnergyUser>> ReceiveEnergyUsersAsync() {
            List<EnergyUser> energyUsers = new List<EnergyUser>();
            List<string> lockTokens = new List<string>();
            
            this.ReceiveMessages()
                .ForEach((message) => {
                    if (message.Body != null) {
                        energyUsers.Add(JsonConvert.DeserializeObject<EnergyUser>(Encoding.UTF8.GetString(message.Body)));
                    }
                    lockTokens.Add(message.SystemProperties.LockToken);
                });

            _ = this.messageReceiver.CompleteAsync(lockTokens);
            return await Task.FromResult(energyUsers);
        }

        private List<Message> ReceiveMessages() {
            return this.messageReceiver.ReceiveAsync(this.maximumMessages)
                            .GetAwaiter()
                            .GetResult()
                            .ToList();
        }
    }

可以看出，它依赖于Microsoft.Azure.ServiceBus.Core.IMessageReceiver.

我第一次尝试模拟这个是使用Moq. 我本来希望如果我创建一个new Mock<IMessageReceiver>()，我应该能够将它注入到public ServiceBusClient(IMessageReceiver messageReceiver, int maximumMessages)中，但是编译器告诉我“错误 CS1503 参数 1：无法从 'Moq.Mock<Microsoft.Azure.ServiceBus.Core.IMessageReceiver>' 转换为'Microsoft.Azure.ServiceBus.Core.IMessageReceiver"....

然后我想我会尝试手动模拟这个类：

    internal class MockMessageReceiver : IMessageReceiver {
        public int ReceivedMaxMessgeCount { get; set; }
        public IList<Message> ReturnMessages { get; set; }
        Task<IList<Message>> IMessageReceiver.ReceiveAsync(int maxMessageCount) {
            this.ReceivedMaxMessgeCount = maxMessageCount;
            return Task.FromResult(this.ReturnMessages);
        }

        public IEnumerable<string> ReceivedLockTokens { get; set; }
        Task IMessageReceiver.CompleteAsync(IEnumerable<string> lockTokens) {
            this.ReceivedLockTokens = lockTokens;
            return Task.Delay(1);
        }

        // Many functions which do nothing just to satisfy the bloated interface.
}

这将允许我成功提供消息，除了我提供的消息不包括 SystemProperties，因此 ServiceBusClient 将在lockTokens.Add(message.SystemProperties.LockToken).

事实证明，该Microsoft.Azure.ServiceBus.Message实现不提供 setter for public SystemPropertiesCollection SystemProperties，因此要设置它（除非有人有更好的方法），我需要创建自己的 Message 实现：

    public class MockMessage : Message {
        public MockMessage(byte[] body) => base.Body = body;

        public new SystemPropertiesCollection SystemProperties {
            get { return this.SystemProperties; }
            set { this.SystemProperties = value; }
        }
    }

现在，我可以初始化 SystemPropertiesCollection，但问题是 SystemPropertiesCollection 中没有任何属性实际上包含设置，所以我的测试仍然会失败。

然后我想：让我们为“SystemPropertiesCollection”创建一个模拟（不要介意我们开始在“太多模拟”的危险水域中游泳......但是当我尝试扩展这个类时，我的编译器抱怨因为 SystemPropertiesCollection 是实际上是一个密封类，所以我不能扩展它。

所以，现在我回到第一方。

有什么想法可以为 ServiceBusClient 创建好的单元测试吗？

4

3 回答 3

4

TL;博士

遇到了同样的问题，并通过利用反射来访问类的私有成员来解决它Message.SystemPropertiesCollection。

更详细的解释

为了避免这种情况message.SystemProperties.LockToken，InvalidOperationException您必须将Message.SystemPropertiesCollection.SequenceNumber属性设置为 -1 以外的值。但是该属性的设置器是私有的，类Message.SystemPropertiesCollection是密封的，并且没有其他间接方法可以设置序列号而不实际通过服务总线发送消息。您不想在单元测试中这样做。

但是用反射作弊来调用Message.SystemPropertiesCollection.SequenceNumber解决这个障碍的私人二传手，让我伪造Message不扔的物体。

示例代码

这个辅助方法生成Message不抛出的对象。

private static Message GenerateSaneMessage()
{
    var message = new Message();
    var sysCollectionType = typeof(Message.SystemPropertiesCollection);
    sysCollectionType.GetProperty(nameof(Message.SystemPropertiesCollection.SequenceNumber))!
        .SetValue(message.SystemProperties, 0);
    return message;
}
于 2021-05-28T07:12:34.893 回答
1

这new Mock<IMessageReceiver>()将返回一个 Mock 实例。但是，您的构造函数需要 IMessageReceiver。这就是编译器显示错误的原因。

Object您必须通过调用模拟上的属性来获取实例，如下所示：

var serviceBusClient = new ServiceBusClient(
    new Mock<IMessageReceiver>().Object, 
    0
);
于 2021-04-01T01:06:40.417 回答
1

虽然不是理想的解决方案，但我在当前打开的 GitHub 问题中找到了一些建议。

一种是有一个 RunInternalAsync 方法，它接受一个调用相同实现的 IReceiverClient messageReceiver https://github.com/Azure/azure-functions-servicebus-extension/issues/69

该问题帖子中建议的代码：

// Called by the Service Bus binding.
[FunctionName("Foo")]
public Task RunAsync(
    [ServiceBusTrigger] Message serviceBusMessage,
    MessageReceiver messageReceiver) => RunInternalAsync(serviceBusMessage, messageReceiver);

// Called by unit tests.
internal Task RunInternalAsync(
    Message serviceBusMessage, 
    IReceiverClient messageReceiver { 
    // Implementation
}

我最终选择了一个可以在单元测试中设置的属性，然后你在你的函数代码中适当地映射它。如此处所述： https ://github.com/Azure/azure-webjobs-sdk/pull/2218#issuecomment-647584346

示例代码：

//Azure Function:
public class ServiceReportingFunction
{
    private ILogger<ServiceReportingFunction> Logger { get; }

    //Needed for unit testing until 'IMessageReceiver messageReceiver' is supported as argument in the Run Method.
    public IMessageReceiver MessageReceiver { get; set; }


    public ServiceReportingFunction(ILogger<ServiceReportingFunction> logger)
    {
        Logger = logger;
    }

    [FunctionName("ServiceReportingFunction")]
    public async Task Run([ServiceBusTrigger("%ServiceReportingQueueName%", Connection = "ServiceBusConnectionString")]Message message, MessageReceiver messageReceiver)
    {
        if (MessageReceiver == null)
            MessageReceiver = messageReceiver;

        ...
    }
}

//Unit (Xunit) test:
public class ServiceReportingFunctionTests
{
    [Fact]
    public async void Test_ServiceReportingFunction()
    {
        var logger = A.Fake<ILogger<ServiceReportingFunction>>();
        var messageReceiver = A.Fake<IMessageReceiver>();

        var function = new ServiceReportingFunction(logger);
        function.MessageReceiver = messageReceiver;
        
        ....

        await function.Run(message, null);

       ....
    }
}
于 2021-03-31T23:45:19.107 回答