伪造 Confluent .NET Kafka 消费者

Question

环境：.NET 4.5。 FakeItEasy : 4.0.0

我正在尝试创建一个 Kafka 消费者的假对象，下面是我使用的语法：

var fakeconsumer = A.Fake<Consumer<Null, string>>((x => x.WithArgumentsForConstructor(() => new Consumer<Null, string>(A.Dummy<IEnumerable<KeyValuePair<string, object>>>(), A.Dummy<IDeserializer<Null>>(), A.Dummy<StringDeserializer>()))));

Kafka客户端的代码在这里：https://github.com/confluentinc/confluent-kafka-dotnet/blob/master/src/Confluent.Kafka/Consumer.cs

如您所见，我正在使用构造函数所需的正确参数调用 Fake 调用。但是我不断收到以下错误消息："No constructor matches the passed arguments for constructor.".

非常感谢任何帮助。

谢谢

编辑：

at FakeItEasy.Creation.CastleDynamicProxy.CastleDynamicProxyGenerator.CreateProxyGeneratorResult(Type typeOfProxy, ProxyGenerationOptions options, IEnumerable1 additionalInterfacesToImplement, IEnumerable1 argumentsForConstructor, IFakeCallProcessorProvider fakeCallProcessorProvider) in C:\projects\fakeiteasy\src\FakeItEasy\Creation\CastleDynamicProxy\CastleDynamicProxyGenerator.cs:line 125 at FakeItEasy.Creation.CastleDynamicProxy.CastleDynamicProxyGenerator.GenerateProxy(Type typeOfProxy, ProxyGenerationOptions options, IEnumerable1 additionalInterfacesToImplement, IEnumerable1 argumentsForConstructor, IFakeCallProcessorProvider fakeCallProcessorProvider) in C:\projects\fakeiteasy\src\FakeItEasy\Creation\CastleDynamicProxy\CastleDynamicProxyGenerator.cs:line 86 at FakeItEasy.Creation.FakeObjectCreator.GenerateProxy(Type typeOfFake, IProxyOptions proxyOptions, IEnumerable1 argumentsForConstructor) in C:\projects\fakeiteasy\src\FakeItEasy\Creation\FakeObjectCreator.cs:line 113 at FakeItEasy.Creation.FakeObjectCreator.CreateFake(Type typeOfFake, IProxyOptions proxyOptions, DummyCreationSession session, IDummyValueResolver resolver, Boolean throwOnFailure) in C:\projects\fakeiteasy\src\FakeItEasy\Creation\FakeObjectCreator.cs:line 36 at FakeItEasy.Creation.DefaultFakeAndDummyManager.CreateFake(Type typeOfFake, Action1 optionsBuilder) in C:\projects\fakeiteasy\src\FakeItEasy\Creation\DefaultFakeAndDummyManager.cs:line 41 at FakeItEasy.A.Fake[T](Action`1 optionsBuilder) in C:\projects\fakeiteasy\src\FakeItEasy\A.cs:line 47

Answer 1

我不是 Kafka 消费者 class 方面的专家，但看起来您是这样调用它的：

Consumer<Null, string>

但我能在代码中找到的唯一构造函数是：

public Consumer(
         IEnumerable<KeyValuePair<string, object>> config)

public Consumer(
            IEnumerable<KeyValuePair<string, object>> config,
            IDeserializer<TKey> keyDeserializer,
            IDeserializer<TValue> valueDeserializer)

所以没有匹配。看起来您想使用第一个，所以您缺少 IEnumerable 部分。

Answer 2

我相信我已经重现了你的问题。这是我看到的完整异常：

FakeItEasy.Core.FakeCreationException : 
  Failed to create fake of type Confluent.Kafka.Consumer`2[Confluent.Kafka.Null,System.String] with the specified arguments for the constructor:
    No constructor matches the passed arguments for constructor.
    An exception of type System.ArgumentException was caught during this call. Its message was:
    'group.id' configuration parameter is required and was not specified.
       at Confluent.Kafka.Consumer..ctor(IEnumerable`1 config)
       at Confluent.Kafka.Consumer`2..ctor(IEnumerable`1 config, IDeserializer`1 keyDeserializer, IDeserializer`1 valueDeserializer)
       at Castle.Proxies.Consumer`2Proxy..ctor(IInterceptor[] , IEnumerable`1 , IDeserializer`1 , IDeserializer`1 )
    at FakeItEasy.Core.DefaultExceptionThrower.ThrowFailedToGenerateProxyWithArgumentsForConstructor(Type typeOfFake, String reasonForFailure)
    at FakeItEasy.Creation.FakeObjectCreator.AssertThatProxyWasGeneratedWhenArgumentsForConstructorAreSpecified(Type typeOfFake, ProxyGeneratorResult result, IProxyOptions proxyOptions)
    at FakeItEasy.Creation.FakeObjectCreator.CreateFake(Type typeOfFake, IProxyOptions proxyOptions, DummyCreationSession session, IDummyValueResolver resolver, Boolean throwOnFailure)
    at FakeItEasy.Creation.DefaultFakeAndDummyManager.CreateFake(Type typeOfFake, Action`1 optionsBuilder)
    at FakeItEasy.A.Fake[T](Action`1 optionsBuilder)
    Kafka.cs(14,0): at FakeItEasyQuestions2015.Kafka.MakeConsumer()

可以看到FakeItEasy本身在调用Consumerclass的构造函数时遇到了异常：

An exception of type System.ArgumentException was caught during this call. Its message was:
    'group.id' configuration parameter is required and was not specified.

这是从 Consumer constructor on line 756:

抛出的

if (config.FirstOrDefault(prop => string.Equals(prop.Key, "group.id", StringComparison.Ordinal)).Value == null)
{
    throw new ArgumentException("'group.id' configuration parameter is required and was not specified.");
}

好像

Consumer(IEnumerable<KeyValuePair<string, object>> config,
         IDeserializer<TKey> keyDeserializer,
         IDeserializer<TValue> valueDeserializer)`

对其输入有一些未满足的要求。特别是，它似乎需要 config 来包含一个键为 "group.id" 的元素。如果我将您的代码更改为

var fakeconsumer = A.Fake<Consumer<Null, string>>(
    (x => x.WithArgumentsForConstructor(
        () => new Consumer<Null, string>(new [] { new KeyValuePair<string, object>("group.id", "hippo")},
        A.Dummy<IDeserializer<Null>>(),
        A.Dummy<StringDeserializer>()))));

造假

我注意到您交叉发布到 FakeItEasy Issue 1176。我会在那里做个笔记来这里回答这个问题。

Answer 3

不是 100% 与原始问题相关，而是在我的图书馆中（Silverback：https://github.com/BEagle1984/silverback) I have a mocked in-memory implementation of the Confluent.Kafka library, that allows for kinda sophisticated integration tests. See some simple examples: https://silverback-messaging.net/concepts/broker/testing.html。

只是给你一个想法：

[Fact]
public async Task SampleTest()
{
    // Arrange
    var testingHelper = _factory.Server.Host.Services
        .GetRequiredService<IKafkaTestingHelper>();

    var producer = testingHelper.Broker
        .GetProducer(new KafkaProducerEndpoint("tst-topic"));

    // Act
    await producer.ProduceAsync(new TestMessage { Content = "abc" });

    await testingHelper.WaitUntilAllMessagesAreConsumedAsync();

    // Assert
    testingHelper.Spy.OutboundEnvelopes.Should().HaveCount(1);
    testingHelper.Spy.InboundEnvelopes.Should().HaveCount(1);
    testingHelper.Spy.InboundEnvelopes[0].Message.As<TestMessage>
        .Content.Should().Be("abc");
}

实现并不复杂，但它支持分区和重新平衡机制的模拟。查看实现：https://github.com/BEagle1984/silverback/tree/master/src/Silverback.Integration.Kafka.Testing/Messaging/Broker/Kafka

伪造 Confluent .NET Kafka 消费者

Faking Confluent .NET Kafka consumers

c#

unit-testing

fakeiteasy

apache-kafka

kafka-consumer-api