如何模拟URLSession.DataTaskPublisher

问题描述

如何模拟URLSession.DataTaskPublisher?我有一个需要注入URLSessionProtocol

How can I mock URLSession.DataTaskPublisher? I have a class Proxy that require to inject a URLSessionProtocol

protocol URLSessionProtocol {
    func loadData(from url: URL) -> URLSession.DataTaskPublisher
}

class Proxy {

    private let urlSession: URLSessionProtocol

    init(urlSession: URLSessionProtocol) {
        self.urlSession = urlSession
    }

    func get(url: URL) -> AnyPublisher<Data, ProxyError> {
        // Using urlSession.loadData(from: url)
    }

}

此代码最初与带有完成处理程序的URLSession的传统版本一起使用.这是完美的，因为我可以在此处轻松模拟URLSession以进行类似Sundell的解决方案的测试:模拟在Swift 中.

This code was originally used with the traditional version of URLSession with the completion handler. It was perfect since I could easily mock URLSession for testing like Sundell's solution here: Mocking in Swift.

是否可以对Combine Framework进行相同的操作?

Is it possible to do the same with the Combine Framework?

推荐答案

与注入URLSessionProtocol来模拟具体会话的方式相同，也可以注入模拟的Publisher.例如:

In the same way that you can inject a URLSessionProtocol to mock a concrete session, you can also inject a mocked Publisher. For example:

let mockPublisher = Just(MockData()).eraseToAnyPublisher()

但是，取决于您对这个发布者的处理方式，您可能需要解决与Combine async出版者的某些怪异之处，请参阅此帖子以进行其他讨论:

However, depending on what you do with this publisher you might have to address some weirdnesses with Combine async publishers, see this post for additional discussion:

为什么Combine的receive(on :)运算符会误入错误?

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