Add initial support for Combine, tests still need to be added

Author: galbernator

Sources/ObservableNetworking/Protocols/Network.swift

@@ -7,10 +7,17 @@
 
 import Foundation
 import RxSwift
+import Combine
 
 public protocol Network {
     // RxSwift
     func request(method: HTTPMethod, endpoint: String, parameters: [String : Any]?, headers: [String : String]?) -> Observable<Result<Data, NetworkError>>
     func authenticatedRequest(method: HTTPMethod, endpoint: String, parameters: [String : Any]?, headers: [String : String]?) -> Observable<Result<Data, NetworkError>>
+
+    // Combine
+    @available(iOS 13.0, *)
+    func request(method: HTTPMethod, endpoint: String, parameters: [String : Any]?, headers: [String : String]?) -> AnyPublisher<Data, NetworkError>
+    @available(iOS 13.0, *)
+    func authenticatedRequest(method: HTTPMethod, endpoint: String, parameters: [String : Any]?, headers: [String : String]?) -> AnyPublisher<Data, NetworkError>
 }
 

Sources/ObservableNetworking/Protocols/Session.swift

@@ -6,18 +6,27 @@
 //
 
 import Foundation
+import Combine
 
 /// Protocol that allows dependecy injection for the express purpose of mocking `URLSession` during testing. This should not be used elsewhere
 public protocol Session {
     typealias DataTaskResult = (Data?, URLResponse?, Error?) -> Void
     func dataTask(with request: NSURLRequest, completionHandler: @escaping DataTaskResult) -> DataTask
+
+    @available(iOS 13.0, *)
+    func dataTaskPublisher<T: TaskPublisher>(for request: URLRequest) -> T
 }
 
 // Make URLSession connform to Session protocol
 extension URLSession: Session {
     public func dataTask(with request: NSURLRequest, completionHandler: @escaping DataTaskResult) -> DataTask {
         return dataTask(with: request, completionHandler: completionHandler) as DataTask
     }
+
+    @available(iOS 13.0, *)
+    public func dataTaskPublisher<T: TaskPublisher>(for request: URLRequest) -> T {
+        return dataTaskPublisher(for: request) as T
+    }
 }
 
 /// Protocol that allows dependecy injection for the express purpose of mocking `URLSession` during testing. This should not be used elsewhere
@@ -27,3 +36,15 @@ public protocol DataTask {
 
 // Make URLSessionDataTask conform to DataTask protocol
 extension URLSessionDataTask: DataTask {}
+
+/// Protocol that allows dependecy injection for the express purpose of mocking `URLSession` during testing. This should not be used elsewhere
+@available(iOS 13.0, *)
+public protocol TaskPublisher: Publisher {
+}
+
+// Make DataTaskPublisher conform to TaskPublisher protocol
+@available(iOS 13.0, *)
+extension URLSession.DataTaskPublisher: TaskPublisher {}
+
+@available(iOS 13.0, *)
+extension AnyPublisher: TaskPublisher {}

Tests/ObservableNetworkingTests/MockURLSession.swift

@@ -7,6 +7,7 @@
 
 import Foundation
 import ObservableNetworking
+import Combine
 
 class MockURLSession: Session {
 
@@ -45,6 +46,12 @@ class MockURLSession: Session {
         return dataTask
     }
 
+    @available(iOS 13.0, *)
+    func dataTaskPublisher<T>(for request: URLRequest) -> T where T : TaskPublisher {
+        lastURL = request.url
+        return MockDataTaskPublisher() as! T
+    }
+
     private func createCookieHeader(for url: URL?) -> [String : String] {
         guard let cookieURL = url else { return [:] }
 
@@ -70,3 +77,27 @@ class MockURLSessionDataTask: DataTask {
         resumeWasCalled = true
     }
 }
+
+class MockDataTaskPublisher: TaskPublisher {
+    typealias Output = Data
+    typealias Failure = NetworkError
+
+    @available(iOS 13.0, *)
+    func receive<S>(subscriber: S) where S : Subscriber, MockDataTaskPublisher.Failure == S.Failure, MockDataTaskPublisher.Output == S.Input {}
+}
+
+@available(iOS 13.0, *)
+extension Data: Subscriber {
+    public typealias Input = Self
+    public typealias Failure = NetworkError
+
+    public var combineIdentifier: CombineIdentifier {
+        CombineIdentifier()
+    }
+
+    public func receive(subscription: Subscription) {}
+
+    public func receive(completion: Subscribers.Completion<NetworkError>) {}
+
+    public func receive(_ input: Data) -> Subscribers.Demand { .unlimited }
+}