Add request completion delegate, rename pre-flight delegate

Sources/Apollo/GraphQLHTTPRequestError.swift

@@ -7,7 +7,7 @@ public enum GraphQLHTTPRequestError: Error, LocalizedError {
   public var errorDescription: String? {
     switch self {
     case .cancelledByDeveloper:
-      return "The request was cancelled by the developer using the HTTPNetworkTransportDelegate."
+      return "The request was cancelled by the developer using the HTTPNetworkTransportPreflightDelegate."
     case .serializedBodyMessageError:
       return "JSONSerialization error: Error while serializing request's body"
     case .serializedQueryParamsMessageError:

Sources/Apollo/HTTPNetworkTransport.swift

@@ -1,6 +1,7 @@
 import Foundation
 
-public protocol HTTPNetworkTransportDelegate: class {
+/// Methods which will be called prior to a request being sent to the server.
+public protocol HTTPNetworkTransportPreflightDelegate: class {
 
   /// Called when a request is about to send, to validate that it should be sent.
   /// Good for early-exiting if your user is not logged in, for example.
@@ -20,13 +21,33 @@ public protocol HTTPNetworkTransportDelegate: class {
   func networkTransport(_ networkTransport: HTTPNetworkTransport, willSend request: inout URLRequest)
 }
 
+// MARK: -
+
+/// Methods which will be called after some kind of response has been received to a `URLSessionTask`.
+public protocol HTTPNetworkTransportTaskCompletedDelegate {
+
+  /// A callback to allow hooking in URL session responses for things like logging and examining headers.
+  /// NOTE: This will call back on whatever thread the URL session calls back on, which is never the main thread. Call `DispatchQueue.main.async` before touching your UI!
+  ///
+  /// - Parameters:
+  ///   - networkTransport: The network transport that completed a task
+  ///   - request: The request which was completed by the task
+  ///   - data: [optional] Any data received. Passed through from `URLSession`.
+  ///   - response: [optional] Any response received. Passed through from `URLSession`.
+  ///   - error: [optional] Any error received. Passed through from `URLSession`.
+  func networkTransport(_ networkTransport: HTTPNetworkTransport, completedRequest request: URLRequest, withData data: Data?, response: URLResponse?, error: Error?)
+}
+
+// MARK: -
+
 /// A network transport that uses HTTP POST requests to send GraphQL operations to a server, and that uses `URLSession` as the networking implementation.
 public class HTTPNetworkTransport: NetworkTransport {
   let url: URL
   let session: URLSession
   let serializationFormat = JSONSerializationFormat.self
   let useGETForQueries: Bool
-  let delegate: HTTPNetworkTransportDelegate?
+  let preflightDelegate: HTTPNetworkTransportPreflightDelegate?
+  let taskCompletedDelegate: HTTPNetworkTransportTaskCompletedDelegate?
 
   /// Creates a network transport with the specified server URL and session configuration.
   ///
@@ -35,16 +56,20 @@ public class HTTPNetworkTransport: NetworkTransport {
   ///   - configuration: A session configuration used to configure the session. Defaults to `URLSessionConfiguration.default`.
   ///   - sendOperationIdentifiers: Whether to send operation identifiers rather than full operation text, for use with servers that support query persistence. Defaults to false.
   ///   - useGETForQueries: If query operation should be sent using GET instead of POST. Defaults to false.
+  ///   - preflightDelegate: A delegate to check with before sending a request.
+  ///   - requestCompletionDelegate: A delegate to notify when the URLSessionTask has completed.
   public init(url: URL,
               configuration: URLSessionConfiguration = .default,
               sendOperationIdentifiers: Bool = false,
               useGETForQueries: Bool = false,
-              delegate: HTTPNetworkTransportDelegate? = nil) {
+              preflightDelegate: HTTPNetworkTransportPreflightDelegate? = nil,
+              requestCompletionDelegate: HTTPNetworkTransportTaskCompletedDelegate? = nil) {
     self.url = url
     self.session = URLSession(configuration: configuration)
     self.sendOperationIdentifiers = sendOperationIdentifiers
     self.useGETForQueries = useGETForQueries
-    self.delegate = delegate
+    self.preflightDelegate = preflightDelegate
+    self.taskCompletedDelegate = requestCompletionDelegate
   }
 
   /// Send a GraphQL operation to a server and return a response.
@@ -65,6 +90,14 @@ public class HTTPNetworkTransport: NetworkTransport {
     }
 
     let task = session.dataTask(with: request) { (data: Data?, response: URLResponse?, error: Error?) in
+      if let requestCompletion = self.taskCompletedDelegate {
+        requestCompletion.networkTransport(self,
+                                           completedRequest: request,
+                                           withData: data,
+                                           response: response,
+                                           error: error)
+      }
+
       if error != nil {
         completionHandler(nil, error)
         return
@@ -126,7 +159,7 @@ public class HTTPNetworkTransport: NetworkTransport {
     request.setValue("application/json", forHTTPHeaderField: "Content-Type")
 
     // If there's a delegate, do a pre-flight check and allow modifications to the request.
-    if let delegate = self.delegate {
+    if let delegate = self.preflightDelegate {
       guard delegate.networkTransport(self, shouldSend: request) else {
         throw GraphQLHTTPRequestError.cancelledByDeveloper
       }

Tests/ApolloTests/HTTPTransportTests.swift

@@ -14,13 +14,19 @@ class HTTPTransportTests: XCTestCase {
 
   private var updatedHeaders: [String: String]?
   private var shouldSend = true
+
+  private var completedRequest: URLRequest?
+  private var completedData: Data?
+  private var completedResponse: URLResponse?
+  private var completedError: Error?
 
   private lazy var url = URL(string: "http://localhost:8080/graphql")!
   private lazy var networkTransport = HTTPNetworkTransport(url: self.url,
                                                            useGETForQueries: true,
-                                                           delegate: self)
+                                                           preflightDelegate: self,
+                                                           requestCompletionDelegate: self)
 
-  func testDelegateTellingRequestNotToSend() {
+  func testPreflightDelegateTellingRequestNotToSend() {
     self.shouldSend = false
 
     let expectation = self.expectation(description: "Send operation completed")
@@ -44,7 +50,7 @@ class HTTPTransportTests: XCTestCase {
       }
     }
 
-    guard (cancellable as? ErrorCancellable) != nil else {
+    guard (cancellable as? EmptyCancellable) != nil else {
       XCTFail("Wrong cancellable type returned!")
       cancellable.cancel()
       expectation.fulfill()
@@ -53,9 +59,15 @@ class HTTPTransportTests: XCTestCase {
 
     // This should fail without hitting the network.
     self.wait(for: [expectation], timeout: 1)
+
+    // The request shouldn't have fired, so all these objects should be nil
+    XCTAssertNil(self.completedRequest)
+    XCTAssertNil(self.completedData)
+    XCTAssertNil(self.completedResponse)
+    XCTAssertNil(self.completedError)
   }
 
-  func testDelgateModifyingRequest() {
+  func testPreflightDelgateModifyingRequest() {
     self.updatedHeaders = ["Authorization": "Bearer HelloApollo"]
 
     let expectation = self.expectation(description: "Send operation completed")
@@ -100,9 +112,15 @@ class HTTPTransportTests: XCTestCase {
 
     // This will come through after hitting the network.
     self.wait(for: [expectation], timeout: 10)
+
+    // We should have everything except an error since the request should have proceeded
+    XCTAssertNotNil(self.completedRequest)
+    XCTAssertNotNil(self.completedData)
+    XCTAssertNotNil(self.completedResponse)
+    XCTAssertNil(self.completedError)
   }
 
-  func testDelegateNeitherModifyingOrStoppingRequest() {
+  func testPreflightDelegateNeitherModifyingOrStoppingRequest() {
     let expectation = self.expectation(description: "Send operation completed")
     let cancellable = self.networkTransport.send(operation: HeroNameQuery()) { (response, error) in
 
@@ -145,10 +163,16 @@ class HTTPTransportTests: XCTestCase {
 
     // This will come through after hitting the network.
     self.wait(for: [expectation], timeout: 10)
+
+    // We should have everything except an error since the request should have proceeded
+    XCTAssertNotNil(self.completedRequest)
+    XCTAssertNotNil(self.completedData)
+    XCTAssertNotNil(self.completedResponse)
+    XCTAssertNil(self.completedError)
   }
 }
 
-extension HTTPTransportTests: HTTPNetworkTransportDelegate {
+extension HTTPTransportTests: HTTPNetworkTransportPreflightDelegate {
   func networkTransport(_ networkTransport: HTTPNetworkTransport, shouldSend request: URLRequest) -> Bool {
     return self.shouldSend
   }
@@ -167,3 +191,13 @@ extension HTTPTransportTests: HTTPNetworkTransportDelegate {
     }
   }
 }
+
+extension HTTPTransportTests: HTTPNetworkTransportTaskCompletedDelegate {
+
+  func networkTransport(_ networkTransport: HTTPNetworkTransport, completedRequest request: URLRequest, withData data: Data?, response: URLResponse?, error: Error?) {
+    self.completedRequest = request
+    self.completedData = data
+    self.completedResponse = response
+    self.completedError = error
+  }
+}