Implementing SWA delegates in specific class

AppleAuthenticationProvider.swift

public func authorizationController(controller: ASAuthorizationController, didCompleteWithAuthorization authorization: ASAuthorization) {
  // Call didFetch(authorizationCredential:)
}

//To test didFetch(authorizationCredential:), mock ASAuthorizationAppleIDCredentialProtocol and 
//assert that your delegate is being called properly
func didFetch(authorizationCredential: ASAuthorizationAppleIDCredentialProtocol) {
  let credential = mapCredential(from: authorizationCredential)
  delegate?.didCompleteWith(credential: credential)
}