Parity: Networking: URLAuthenticationChallenge

The class is mostly implemented, but there are several NSUnimplemented() that mark methods that, according to URLSession’s contract, are not meant to be invoked. Replace them with more verbose fatalErrors().

Author: millenomi

Foundation/URLAuthenticationChallenge.swift

@@ -199,25 +199,24 @@ open class URLAuthenticationChallenge : NSObject, NSSecureCoding {
     }
 }
 
-extension _HTTPURLProtocol : URLAuthenticationChallengeSender {
-
+class URLSessionAuthenticationChallengeSender : NSObject, URLAuthenticationChallengeSender {
     func cancel(_ challenge: URLAuthenticationChallenge) {
-        NSUnimplemented()
+        fatalError("swift-corelibs-foundation only supports URLSession; for challenges coming from URLSession, please implement the appropriate URLSessionTaskDelegate methods rather than using the sender argument.")
     }
 
     func continueWithoutCredential(for challenge: URLAuthenticationChallenge) {
-        NSUnimplemented()
+        fatalError("swift-corelibs-foundation only supports URLSession; for challenges coming from URLSession, please implement the appropriate URLSessionTaskDelegate methods rather than using the sender argument.")
     }
 
     func use(_ credential: URLCredential, for challenge: URLAuthenticationChallenge) {
-        NSUnimplemented()
+        fatalError("swift-corelibs-foundation only supports URLSession; for challenges coming from URLSession, please implement the appropriate URLSessionTaskDelegate methods rather than using the sender argument.")
     }
 
     func performDefaultHandling(for challenge: URLAuthenticationChallenge) {
-        NSUnimplemented()
+        fatalError("swift-corelibs-foundation only supports URLSession; for challenges coming from URLSession, please implement the appropriate URLSessionTaskDelegate methods rather than using the sender argument.")
     }
 
     func rejectProtectionSpaceAndContinue(with challenge: URLAuthenticationChallenge) {
-        NSUnimplemented()
+        fatalError("swift-corelibs-foundation only supports URLSession; for challenges coming from URLSession, please implement the appropriate URLSessionTaskDelegate methods rather than using the sender argument.")
     }
 }

Foundation/URLSession/URLSessionTask.swift

@@ -758,7 +758,7 @@ extension _ProtocolClient : URLProtocolClient {
 
                     let authenticationChallenge = URLAuthenticationChallenge(protectionSpace: protectionSpace, proposedCredential: proposedCredential,
                                                                              previousFailureCount: task.previousFailureCount, failureResponse: response, error: nil,
-                                                                             sender: urlProtocol as! _HTTPURLProtocol)
+                                                                             sender: URLSessionAuthenticationChallengeSender())
                     task.previousFailureCount += 1
                     self.urlProtocol(urlProtocol, didReceive: authenticationChallenge)
                 }