feat: introduce URLSession extension (#81)

Author: ns-vasilev

Sources/Typhoon/Classes/Extensions/URLSession+RetryPolicy.swift

@@ -0,0 +1,95 @@
+//
+// Typhoon
+// Copyright © 2026 Space Code. All rights reserved.
+//
+
+#if canImport(Darwin)
+    import Foundation
+
+    public extension URLSession {
+        /// Performs a data task with retry policy applied.
+        ///
+        /// - Parameters:
+        ///   - request: The URL request to perform.
+        ///   - strategy: The retry strategy to apply.
+        ///   - onFailure: An optional closure called on each failure. Return `false` to stop retrying early.
+        /// - Returns: A tuple of `(Data, URLResponse)`.
+        func data(
+            for request: URLRequest,
+            retryPolicy strategy: RetryPolicyStrategy,
+            onFailure: (@Sendable (Error) async -> Bool)? = nil
+        ) async throws -> (Data, URLResponse) {
+            try await RetryPolicyService(strategy: strategy).retry(
+                strategy: nil,
+                onFailure: onFailure
+            ) {
+                try await self.data(for: request)
+            }
+        }
+
+        /// Performs a data task for a URL with retry policy applied.
+        ///
+        /// - Parameters:
+        ///   - url: The URL to fetch.
+        ///   - strategy: The retry strategy to apply.
+        ///   - onFailure: An optional closure called on each failure. Return `false` to stop retrying early.
+        /// - Returns: A tuple of `(Data, URLResponse)`.
+        func data(
+            from url: URL,
+            retryPolicy strategy: RetryPolicyStrategy,
+            onFailure: (@Sendable (Error) async -> Bool)? = nil
+        ) async throws -> (Data, URLResponse) {
+            try await RetryPolicyService(strategy: strategy).retry(
+                strategy: nil,
+                onFailure: onFailure
+            ) {
+                try await self.data(from: url)
+            }
+        }
+
+        /// Uploads data for a request with retry policy applied.
+        ///
+        /// - Parameters:
+        ///   - request: The URL request to use for the upload.
+        ///   - bodyData: The data to upload.
+        ///   - strategy: The retry strategy to apply.
+        ///   - onFailure: An optional closure called on each failure. Return `false` to stop retrying early.
+        /// - Returns: A tuple of `(Data, URLResponse)`.
+        func upload(
+            for request: URLRequest,
+            from bodyData: Data,
+            retryPolicy strategy: RetryPolicyStrategy,
+            onFailure: (@Sendable (Error) async -> Bool)? = nil
+        ) async throws -> (Data, URLResponse) {
+            try await RetryPolicyService(strategy: strategy).retry(
+                strategy: nil,
+                onFailure: onFailure
+            ) {
+                try await self.upload(for: request, from: bodyData)
+            }
+        }
+
+        /// Downloads a file for a request with retry policy applied.
+        ///
+        /// - Parameters:
+        ///   - request: The URL request to use for the download.
+        ///   - strategy: The retry strategy to apply.
+        ///   - delegate: A delegate that receives life cycle and authentication challenge callbacks as the transfer progresses.
+        ///   - onFailure: An optional closure called on each failure. Return `false` to stop retrying early.
+        /// - Returns: A tuple of `(URL, URLResponse)` where `URL` is the temporary file location.
+        @available(iOS 15, macOS 12, tvOS 15, watchOS 8, *)
+        func download(
+            for request: URLRequest,
+            retryPolicy strategy: RetryPolicyStrategy,
+            delegate: (any URLSessionTaskDelegate)? = nil,
+            onFailure: (@Sendable (Error) async -> Bool)? = nil
+        ) async throws -> (URL, URLResponse) {
+            try await RetryPolicyService(strategy: strategy).retry(
+                strategy: nil,
+                onFailure: onFailure
+            ) {
+                try await self.download(for: request, delegate: delegate)
+            }
+        }
+    }
+#endif

Tests/TyphoonTests/Helpers/Counter.swift

@@ -0,0 +1,30 @@
+//
+// Typhoon
+// Copyright © 2026 Space Code. All rights reserved.
+//
+
+import Foundation
+
+final class Counter: @unchecked Sendable {
+    private let lock = NSLock()
+    private var _value: UInt = 0
+
+    var value: UInt {
+        lock.withLock { _value }
+    }
+
+    @discardableResult
+    func increment() -> UInt {
+        lock.withLock {
+            _value += 1
+            return _value
+        }
+    }
+
+    @discardableResult
+    func getValue() -> UInt {
+        lock.withLock {
+            _value
+        }
+    }
+}

Tests/TyphoonTests/Mocks/MockURLProtocol.swift

@@ -0,0 +1,36 @@
+//
+// Typhoon
+// Copyright © 2026 Space Code. All rights reserved.
+//
+
+#if canImport(Darwin)
+    import Foundation
+
+    // MARK: - MockURLProtocol
+
+    final class MockURLProtocol: URLProtocol, @unchecked Sendable {
+        override class func canInit(with _: URLRequest) -> Bool {
+            true
+        }
+
+        override class func canonicalRequest(for request: URLRequest) -> URLRequest {
+            request
+        }
+
+        override func startLoading() {
+            let client = client
+            Task {
+                do {
+                    let (response, data) = try await MockURLProtocolHandler.shared.callHandler()
+                    client?.urlProtocol(self, didReceive: response, cacheStoragePolicy: .notAllowed)
+                    client?.urlProtocol(self, didLoad: data)
+                    client?.urlProtocolDidFinishLoading(self)
+                } catch {
+                    client?.urlProtocol(self, didFailWithError: error)
+                }
+            }
+        }
+
+        override func stopLoading() {}
+    }
+#endif

Tests/TyphoonTests/Mocks/MockURLProtocolHandler.swift

@@ -0,0 +1,27 @@
+//
+// Typhoon
+// Copyright © 2026 Space Code. All rights reserved.
+//
+
+#if canImport(Darwin)
+    import Foundation
+
+    // MARK: - MockURLProtocolHandler
+
+    actor MockURLProtocolHandler {
+        typealias Handler = @Sendable () throws -> (HTTPURLResponse, Data)
+
+        static let shared = MockURLProtocolHandler()
+
+        private var handler: Handler?
+
+        func set(_ handler: Handler?) {
+            self.handler = handler
+        }
+
+        func callHandler() throws -> (HTTPURLResponse, Data) {
+            guard let handler else { throw URLError(.unknown) }
+            return try handler()
+        }
+    }
+#endif

…yPolicyServiceRetryWithResultTests.swift …yPolicyServiceRetryWithResultTests.swiftTests/TyphoonTests/UnitTests/RetryPolicyServiceRetryWithResultTests.swift renamed to Tests/TyphoonTests/UnitTests/RetryService/RetryPolicyServiceRetryWithResultTests.swift Tests/TyphoonTests/UnitTests/RetryPolicyServiceRetryWithResultTests.swift renamed to Tests/TyphoonTests/UnitTests/RetryService/RetryPolicyServiceRetryWithResultTests.swift

@@ -16,53 +16,51 @@ final class RetryPolicyServiceRetryWithResultTests: XCTestCase {
         case fatal
     }
 
-    // MARK: - Counter
-
-    private actor Counter {
-        private(set) var count: Int = 0
-
-        func increment() {
-            count += 1
-        }
-    }
-
     // MARK: Tests
 
     func test_retryWithResult_succeedsOnFirstAttempt() async throws {
+        // given
         let sut = RetryPolicyService(strategy: .constant(retry: 3, dispatchDuration: .milliseconds(10)))
 
+        // when
         let result = try await sut.retryWithResult {
             42
         }
 
+        // then
         XCTAssertEqual(result.value, 42)
         XCTAssertEqual(result.attempts, 1)
         XCTAssertTrue(result.errors.isEmpty)
         XCTAssertGreaterThanOrEqual(result.totalDuration, 0)
     }
 
     func test_retryWithResult_succeedsAfterSeveralFailures() async throws {
+        // given
         let sut = RetryPolicyService(strategy: .constant(retry: 5, dispatchDuration: .milliseconds(10)))
 
         let counter = Counter()
 
+        // when
         let result = try await sut.retryWithResult {
-            await counter.increment()
-            if await counter.count < 3 {
+            counter.increment()
+            if counter.value < 3 {
                 throw TestError.transient
             }
             return "ok"
         }
 
+        // then
         XCTAssertEqual(result.value, "ok")
         XCTAssertEqual(result.attempts, 3)
         XCTAssertEqual(result.errors.count, 2)
         XCTAssertTrue(result.errors.allSatisfy { ($0 as? TestError) == .transient })
     }
 
     func test_retryWithResult_throwsRetryLimitExceeded_whenAllAttemptsFail() async throws {
+        // given
         let sut = RetryPolicyService(strategy: .constant(retry: 3, dispatchDuration: .milliseconds(10)))
 
+        // when
         do {
             _ = try await sut.retryWithResult {
                 throw TestError.transient
@@ -72,102 +70,114 @@ final class RetryPolicyServiceRetryWithResultTests: XCTestCase {
     }
 
     func test_retryWithResult_stopsRetrying_whenOnFailureReturnsFalse() async throws {
+        // given
         let sut = RetryPolicyService(strategy: .constant(retry: 5, dispatchDuration: .milliseconds(10)))
 
         let counter = Counter()
 
+        // when
         do {
             _ = try await sut.retryWithResult(
                 onFailure: { _ in false }
             ) {
-                await counter.increment()
+                counter.increment()
                 throw TestError.fatal
             }
             XCTFail("Expected error to be rethrown")
         } catch {
             XCTAssertEqual(error as? TestError, .fatal)
-            let count = await counter.count
+            let count = counter.value
             XCTAssertEqual(count, 1)
         }
     }
 
     func test_retryWithResult_stopsRetrying_onSpecificError() async throws {
+        // given
         let sut = RetryPolicyService(strategy: .constant(retry: 5, dispatchDuration: .milliseconds(10)))
 
         let counter = Counter()
 
+        // when
         do {
             _ = try await sut.retryWithResult(
                 onFailure: { error in
                     (error as? TestError) == .transient
                 }
             ) {
-                await counter.increment()
-                let current = await counter.count
+                counter.increment()
+                let current = counter.value
                 throw current == 1 ? TestError.transient : TestError.fatal
             }
             XCTFail("Expected error to be rethrown")
         } catch {
             XCTAssertEqual(error as? TestError, .fatal)
-            let count = await counter.count
+            let count = counter.value
             XCTAssertEqual(count, 2)
         }
     }
 
     func test_retryWithResult_onFailureReceivesAllErrors() async throws {
+        // given
         let sut = RetryPolicyService(strategy: .constant(retry: 4, dispatchDuration: .milliseconds(10)))
 
         let counter = Counter()
         let receivedErrors = ErrorCollector()
 
+        // when
         let result = try await sut.retryWithResult(
             onFailure: { error in
                 await receivedErrors.append(error)
                 return true
             }
         ) {
-            await counter.increment()
-            if await counter.count < 4 {
+            counter.increment()
+            if counter.value < 4 {
                 throw TestError.transient
             }
             return "done"
         }
 
+        // then
         XCTAssertEqual(result.value, "done")
         let collected = await receivedErrors.errors
         XCTAssertEqual(collected.count, 3)
         XCTAssertEqual(result.errors.count, 3)
     }
 
     func test_retryWithResult_customStrategyOverridesDefault() async throws {
+        // given
         let sut = RetryPolicyService(strategy: .constant(retry: 10, dispatchDuration: .milliseconds(10)))
         let customStrategy = RetryPolicyStrategy.constant(retry: 2, dispatchDuration: .milliseconds(10))
 
         let counter = Counter()
 
+        // when
         do {
             _ = try await sut.retryWithResult(strategy: customStrategy) {
-                await counter.increment()
+                counter.increment()
                 throw TestError.transient
             }
             XCTFail("Expected retryLimitExceeded")
         } catch RetryPolicyError.retryLimitExceeded {
-            let count = await counter.count
+            let count = counter.value
             XCTAssertLessThanOrEqual(count, 3)
         }
     }
 
     func test_retryWithResult_totalDurationIsNonNegative() async throws {
+        // given
         let sut = RetryPolicyService(strategy: .constant(retry: 3, dispatchDuration: .milliseconds(10)))
 
         let counter = Counter()
 
+        // when
         let result = try await sut.retryWithResult {
-            await counter.increment()
-            if await counter.count < 2 { throw TestError.transient }
+            counter.increment()
+            if counter.value < 2 { throw TestError.transient }
             return true
         }
 
+        // then
         XCTAssertGreaterThanOrEqual(result.totalDuration, 0)
     }
 }