如何执行作为参数传递给模拟服务的通用函数

Question

我有一个在单独的库中实现的服务，并将Func<T> 作为函数的参数。

在模拟服务时，我仍然需要运行 Func<T>。

如何为此设置模拟对象？

我创建了以下代码示例来演示该问题：

// This is the service that is in a different library and I want to mock
public interface IServiceToMock
{
    T ExecuteAsync<T>(Func<T> func);
}

public class ServiceToMock : IServiceToMock
{
    public T ExecuteAsync<T>(Func<T> funcToBeExecuted)
    {
        // does some more logic that I don't want to test
        return funcToBeExecuted();
    }
}

这是服务的消费者

public class ServiceConsumer
{
    private readonly IServiceToMock service;

    public ServiceConsumer(IServiceToMock service) => this.service = service;

    public async Task Consume()
    {
        await service.ExecuteAsync(async () => await ConsumeInteger(1));
        await service.ExecuteAsync(async () => await ConsumeString("String"));
    }

    // This is the method that I want to be triggered when the Consume() is called
    private async Task ConsumeInteger(int number)
    {
        await new Task<int>(() =>
        {
            Console.WriteLine(number);
            return number;
        });
    }

    // This is the method that I want to be triggered when the Consume() is called
    private async Task ConsumeString(string str)
    {
        await new Task<string>(() =>
        {
            Console.WriteLine(str);
            return str;
        });
    }
}

这是我目前的测试

public class TestServiceConsumer
{
    public void TestMethod()
    {
        var moqLibraryService = new Mock<IServiceToMock>();
        // How can I set up the mock to have the Console 
        moqLibraryService.Setup(ms => ms.ExecuteAsync(It.IsAny<Func<T>>())).Returns(T());
    }
}

Answer 1

我认为你可以这样做：

var moqLibraryService = new Mock<IServiceToMock>();

moqLibraryService.Setup(ms => ms.ExecuteAsync(It.IsAny<Func<int>>()))
  .Returns( (Func<int> f) => f() );
moqLibraryService.Setup(ms => ms.ExecuteAsync(It.IsAny<Func<string>>()))
  .Returns( (Func<string> f) => f() );

它使用Returns 的重载，它接收valueFunction 而不仅仅是value。每次模拟完成时，匿名函数(Func<int> f) => f() 将再次被评估。这里f 是传递给 Moq 的任意参数。

如果您不想明确提及类型（此处为int、string），可能会更难做到。这将与线程 Mocking generic methods in Moq without specifying T 有关。