UITest 项目中的协议一致性错误

Question

我在 Swift 中的 UITest 项目中遇到了一个非常奇怪的错误。

Undefined symbols for architecture x86_64:
  "protocol conformance descriptor for IntroductionToMocking.User : Swift.Decodable in IntroductionToMocking", referenced from:
      lazy protocol witness table accessor for type IntroductionToMocking.User and conformance IntroductionToMocking.User : Swift.Decodable in IntroductionToMocking in MockHTTPClient.o
  "protocol descriptor for IntroductionToMocking.HTTPClientProtocol", referenced from:
      protocol conformance descriptor for IntroductionToMockingUITests.MockHTTPClient : IntroductionToMocking.HTTPClientProtocol in IntroductionToMockingUITests in MockHTTPClient.o
  "type metadata for IntroductionToMocking.User", referenced from:
      IntroductionToMockingUITests.MockHTTPClient.authenticate(username: Swift.String, password: Swift.String, completion: (IntroductionToMocking.User?) -> ()) -> () in MockHTTPClient.o
      lazy protocol witness table accessor for type IntroductionToMocking.User and conformance IntroductionToMocking.User : Swift.Decodable in IntroductionToMocking in MockHTTPClient.o

在我的 UITest 项目中，我创建了使用 HTTPClientProtocol 的 MockHTTPClient，如下所示：

import Foundation
@testable import IntroductionToMocking

class MockHTTPClient: HTTPClientProtocol {

    func authenticate(username: String, password: String, completion: @escaping (User?) -> Void) {


        guard let url = Bundle(for: MockHTTPClient.self).url(forResource: "auth-success-response", withExtension: "json"),
            let data = try? Data(contentsOf: url) else {
                return completion(nil)
        }

        let user = try? JSONDecoder().decode(User.self, from: data)
        completion(user)
    }

}

协议在主项目中定义如下：

import Foundation

protocol HTTPClientProtocol {
    func authenticate(username: String, password: String, completion: @escaping (User?) -> Void )
}

我无法弄清楚发生了什么以及为什么会出现错误。有任何想法吗？

Answer 1

在我的情况下，问题与通用应用程序有关。我遇到了问题中提到的相同错误。 这里提到的解决方法https://developer.apple.com/forums/thread/654309 对我有用。这并不理想，但将文件添加到测试目标可以编译和运行测试。

解决方法是将文件也添加到测试目标。 好像是编译时合成代码出错

例如，在我运行测试时的编译错误中，我看到了这个错误：

Undefined symbols for architecture x86_64:
  "nominal type descriptor for MyApp.SMPSmallWidgetConfig", referenced from:
      _symbolic _____y_____G 9Tests_iOS35SMPWidgetsConfigDefaultsPersistenceC 12MyApp014SMPSmallWidgetD0V in SMPWidgetsConfigDefaultsPersistenceTests.o
      _symbolic _____y______ySay_____G_____GSo17OS_dispatch_queueCG 7Combine10PublishersO11SubscribeOnV AA12AnyPublisherV 12MyApp20SMPSmallWidgetConfigV s5NeverO in SMPWidgetsConfigDefaultsPersistenceTests.o
      _symbolic _____y______y______ySay_____G_____GSo17OS_dispatch_queueCGAIG 7Combine10PublishersO9ReceiveOnV AC09SubscribeD0V AA12AnyPublisherV 12MyApp20SMPSmallWidgetConfigV s5NeverO in SMPWidgetsConfigDefaultsPersistenceTests.o
      _symbolic Say_____GSg 12MyApp20SMPSmallWidgetConfigV in SMPWidgetsConfigDefaultsPersistenceTests.o
      _symbolic _____ySay_____G_____G 7Combine12AnyPublisherV 12MyApp20SMPSmallWidgetConfigV s5NeverO in SMPWidgetsConfigDefaultsPersistenceTests.o
      _symbolic Say_____GSgz_Xx 12MyApp20SMPSmallWidgetConfigV in SMPWidgetsConfigDefaultsPersistenceTests.o
      _symbolic Say_____GIegg_ 12MyApp20SMPSmallWidgetConfigV in SMPWidgetsConfigDefaultsPersistenceTests.o
      ...
  "protocol conformance descriptor for MyApp.SMPSmallWidgetConfig : Swift.Equatable in MyApp", referenced from:
      lazy protocol witness table accessor for type MyApp.SMPSmallWidgetConfig and conformance MyApp.SMPSmallWidgetConfig : Swift.Equatable in MyApp in SMPWidgetsConfigDefaultsPersistenceTests.o
  "protocol conformance descriptor for MyApp.SMPSmallWidgetConfig : Swift.Encodable in MyApp", referenced from:
      lazy protocol witness table accessor for type MyApp.SMPSmallWidgetConfig and conformance MyApp.SMPSmallWidgetConfig : Swift.Encodable in MyApp in SMPWidgetsConfigDefaultsPersistenceTests.o
  "type metadata for MyApp.SMPSmallWidgetConfig", referenced from:
      lazy protocol witness table accessor for type MyApp.SMPSmallWidgetConfig and conformance MyApp.SMPSmallWidgetConfig : Swift.Encodable in MyApp in SMPWidgetsConfigDefaultsPersistenceTests.o
      lazy protocol witness table accessor for type MyApp.SMPSmallWidgetConfig and conformance MyApp.SMPSmallWidgetConfig : Swift.Equatable in MyApp in SMPWidgetsConfigDefaultsPersistenceTests.o
  "static MyApp.SMPSmallWidgetConfig.defaultSMPSmallWidgetConfig() -> MyApp.SMPSmallWidgetConfig", referenced from:
      Tests_iOS.SMPWidgetsConfigDefaultsPersistenceTests.(givenSmallConfig in _F12F8146E6B85CC300C4FE7EE03F2059)() -> MyApp.SMPSmallWidgetConfig in SMPWidgetsConfigDefaultsPersistenceTests.o
ld: symbol(s) not found for architecture x86_64

将SMPSmallWidgetConfig 添加到测试目标可以解决编译问题。 这当然是除了拥有 @testable import MyApp 在测试中