Use associatedtypes to clean up URLSession conformance

Author: bsneed

Sources/Segment/Configuration.swift

@@ -67,6 +67,7 @@ public class Configuration {
         var jsonNonConformingNumberStrategy: JSONSafeEncoder.NonConformingFloatEncodingStrategy = .zero
         var storageMode: StorageMode = .disk
         var anonymousIdGenerator: AnonymousIdGenerator = SegmentAnonymousId()
+        var httpSession: (() -> any HTTPSession)? = nil
     }
 
     internal var values: Values
@@ -245,8 +246,8 @@ public extension Configuration {
 
     /// Specify a custom UserAgent string.  This bypasses the OS dependent check entirely.
     @discardableResult
-    func userAgent(_ userAgent: String) -> Configuration {
-        values.userAgent = userAgent
+    func httpSession(_ httpSession: @escaping @autoclosure () -> HTTPSession) -> Configuration {
+        values.httpSession = httpSession
         return self
     }
 

Sources/Segment/Utilities/HTTPClient.swift

@@ -20,8 +20,8 @@ public enum HTTPClientErrors: Error {
 public class HTTPClient {
     private static let defaultAPIHost = "api.segment.io/v1"
     private static let defaultCDNHost = "cdn-settings.segment.com/v1"
-    
-    internal var session: URLSession
+
+    internal var session: any HTTPSession
     private var apiHost: String
     private var apiKey: String
     private var cdnHost: String

Sources/Segment/Utilities/Networking/HTTPSession+Apple.swift

@@ -0,0 +1,11 @@
+import Foundation
+
+#if os(Linux) || os(Windows)
+import FoundationNetworking
+#endif
+
+extension URLSessionDataTask: DataTask {}
+extension URLSessionUploadTask: UploadTask {}
+
+// Give the built in `URLSession` conformance to HTTPSession so that it can easily be used
+extension URLSession: HTTPSession {}

Sources/Segment/Utilities/Networking/HTTPSession.swift

@@ -0,0 +1,33 @@
+import Foundation
+
+#if os(Linux) || os(Windows)
+import FoundationNetworking
+#endif
+
+public protocol DataTask {
+  var state: URLSessionTask.State { get }
+  func resume()
+}
+
+public protocol UploadTask: DataTask {}
+
+// An enumeration of default `HTTPSession` configurations to be used
+// This can be extended buy consumer to easily refer back to their configured session.
+public enum HTTPSessions {
+  /// An implementation of `HTTPSession` backed by Apple's `URLSession`.
+  public static func urlSession() -> any HTTPSession {
+      let configuration = URLSessionConfiguration.ephemeral
+      configuration.httpMaximumConnectionsPerHost = 2
+      let session = URLSession(configuration: configuration, delegate: nil, delegateQueue: nil)
+      return session
+  }
+}
+
+public protocol HTTPSession {
+  associatedtype DataTaskType: DataTask
+  associatedtype UploadTaskType: UploadTask
+
+  func uploadTask(with request: URLRequest, fromFile file: URL, completionHandler: @escaping @Sendable (Data?, URLResponse?, (any Error)?) -> Void) -> UploadTaskType
+  func dataTask(with request: URLRequest, completionHandler: @escaping @Sendable (Data?, URLResponse?, (any Error)?) -> Void) -> DataTaskType
+  func finishTasksAndInvalidate()
+}