Add configuration for URLSessionConfiguration. (#27)

Author: gwhelanLD

Source/LDSwiftEventSource.swift

@@ -67,6 +67,32 @@ public class EventSource {
         /// The maximum amount of time between receiving any data before considering the connection to have timed out.
         public var idleTimeout: TimeInterval = 300.0
 
+        private var _urlSessionConfiguration: URLSessionConfiguration = URLSessionConfiguration.default
+        /**
+         The `URLSessionConfiguration` used to create the `URLSession`.
+
+         - Important:
+            Note that this copies the given `URLSessionConfiguration` when set, and returns copies (updated with any
+         overrides specified by other configuration options) when the value is retrieved. This prevents updating the
+         `URLSessionConfiguration` after initializing `EventSource` with the `Config`, and prevents the `EventSource`
+         from updating any properties of the given `URLSessionConfiguration`.
+
+         - Since: 1.3.0
+         */
+        public var urlSessionConfiguration: URLSessionConfiguration {
+            get {
+                // swiftlint:disable:next force_cast
+                let sessionConfig = _urlSessionConfiguration.copy() as! URLSessionConfiguration
+                sessionConfig.httpAdditionalHeaders = ["Accept": "text/event-stream", "Cache-Control": "no-cache"]
+                sessionConfig.timeoutIntervalForRequest = idleTimeout
+                return sessionConfig
+            }
+            set {
+                // swiftlint:disable:next force_cast
+                _urlSessionConfiguration = newValue.copy() as! URLSessionConfiguration
+            }
+        }
+
         /**
          An error handler that is called when an error occurs and can shut down the client in response.
 
@@ -136,10 +162,7 @@ class EventSourceDelegate: NSObject, URLSessionDataDelegate {
     func getLastEventId() -> String? { lastEventId }
 
     func createSession() -> URLSession {
-        let sessionConfig = URLSessionConfiguration.default
-        sessionConfig.httpAdditionalHeaders = ["Accept": "text/event-stream", "Cache-Control": "no-cache"]
-        sessionConfig.timeoutIntervalForRequest = self.config.idleTimeout
-        return URLSession(configuration: sessionConfig, delegate: self, delegateQueue: nil)
+        URLSession(configuration: config.urlSessionConfiguration, delegate: self, delegateQueue: nil)
     }
 
     func createRequest() -> URLRequest {
@@ -148,7 +171,7 @@ class EventSourceDelegate: NSObject, URLSessionDataDelegate {
                                     timeoutInterval: self.config.idleTimeout)
         urlRequest.httpMethod = self.config.method
         urlRequest.httpBody = self.config.body
-        urlRequest.setValue(self.lastEventId, forHTTPHeaderField: "Last-Event-ID")
+        urlRequest.setValue(self.lastEventId, forHTTPHeaderField: "Last-Event-Id")
         urlRequest.allHTTPHeaderFields = self.config.headerTransform(
             urlRequest.allHTTPHeaderFields?.merging(self.config.headers) { $1 } ?? self.config.headers
         )

Tests/LDSwiftEventSourceTests.swift

@@ -49,6 +49,27 @@ final class LDSwiftEventSourceTests: XCTestCase {
         XCTAssertEqual(config.connectionErrorHandler(DummyError()), .shutdown)
     }
 
+    func testConfigUrlSession() {
+        var config = EventSource.Config(handler: MockHandler(), url: URL(string: "abc")!)
+        let defaultSessionConfig = config.urlSessionConfiguration
+        XCTAssertEqual(defaultSessionConfig.timeoutIntervalForRequest, 300.0)
+        XCTAssertEqual(defaultSessionConfig.httpAdditionalHeaders?["Accept"] as? String, "text/event-stream")
+        XCTAssertEqual(defaultSessionConfig.httpAdditionalHeaders?["Cache-Control"] as? String, "no-cache")
+        // Configuration should return a fresh session configuration each retrieval
+        XCTAssertTrue(defaultSessionConfig !== config.urlSessionConfiguration)
+        // Updating idleTimeout should effect session config
+        config.idleTimeout = 600.0
+        XCTAssertEqual(config.urlSessionConfiguration.timeoutIntervalForRequest, 600.0)
+        XCTAssertEqual(defaultSessionConfig.timeoutIntervalForRequest, 300.0)
+        // Updating returned urlSessionConfiguration without setting should not update the Config until set
+        let sessionConfig = config.urlSessionConfiguration
+        sessionConfig.allowsCellularAccess = false
+        XCTAssertTrue(config.urlSessionConfiguration.allowsCellularAccess)
+        config.urlSessionConfiguration = sessionConfig
+        XCTAssertFalse(config.urlSessionConfiguration.allowsCellularAccess)
+        XCTAssertTrue(sessionConfig !== config.urlSessionConfiguration)
+    }
+
     func testLastEventIdFromConfig() {
         var config = EventSource.Config(handler: MockHandler(), url: URL(string: "abc")!)
         var es = EventSource(config: config)
@@ -86,7 +107,7 @@ final class LDSwiftEventSourceTests: XCTestCase {
         config.headers = testHeaders
         config.idleTimeout = 180.0
         config.headerTransform = { provided in
-            XCTAssertEqual(provided, ["removing": "a", "updating": "b", "Last-Event-ID": "eventId"])
+            XCTAssertEqual(provided, ["removing": "a", "updating": "b", "Last-Event-Id": "eventId"])
             return overrideHeaders
         }
         request = EventSourceDelegate(config: config).createRequest()

Tests/XCTestManifests.swift

@@ -34,6 +34,11 @@ extension LDSwiftEventSourceTests {
     static let __allTests__LDSwiftEventSourceTests = [
         ("testConfigDefaults", testConfigDefaults),
         ("testConfigModification", testConfigModification),
+        ("testConfigUrlSession", testConfigUrlSession),
+        ("testCreatedSession", testCreatedSession),
+        ("testCreateRequest", testCreateRequest),
+        ("testDispatchError", testDispatchError),
+        ("testLastEventIdFromConfig", testLastEventIdFromConfig),
     ]
 }