CancellingContinuationTests

Author: swhitty

FlyingSocks/Sources/CancellingContinuation.swift

@@ -81,13 +81,12 @@ private extension CancellingContinuation {
         func getValue() async throws -> Success {
             precondition(hasStarted == false, "Can only wait a single time.")
             hasStarted = true
-            if let result = result {
-                return try result.get()
-            } else {
+            guard let result = result else {
                 return try await withCheckedThrowingContinuation(function: function) {
                     continuation = $0
                 }
             }
+            return try result.get()
         }
 
         func resume(with result: Result<Success, Error>) {

FlyingSocks/Tests/CancellingContinuationTests.swift

@@ -0,0 +1,101 @@
+//
+//  CancellingContinuationTests.swift
+//  FlyingFox
+//
+//  Created by Simon Whitty on 28/08/2022.
+//  Copyright © 2022 Simon Whitty. All rights reserved.
+//
+//  Distributed under the permissive MIT license
+//  Get the latest version from here:
+//
+//  https://github.com/swhitty/FlyingFox
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import FlyingSocks
+import XCTest
+
+final class CancellingContinuationTests: XCTestCase {
+
+    func testContinuationHashable() {
+        let continuation = CancellingContinuation<String, Never>()
+        let other = CancellingContinuation<String, Never>()
+
+        var continuations = Set([continuation])
+
+        XCTAssertTrue(continuations.contains(continuation))
+        XCTAssertFalse(continuations.contains(other))
+
+        continuations.insert(other)
+        XCTAssertTrue(continuations.contains(continuation))
+        XCTAssertTrue(continuations.contains(other))
+
+        continuations.remove(continuation)
+        XCTAssertFalse(continuations.contains(continuation))
+        XCTAssertTrue(continuations.contains(other))
+    }
+
+    func testEarlyResultIsReturned() async {
+        let continuation = CancellingContinuation<String, Never>()
+
+        continuation.resume(returning: "Fish")
+        let task = Task { try await continuation.value }
+        task.cancel()
+
+        await XCTAssertEqualAsync(
+            try await task.value,
+            "Fish"
+        )
+    }
+
+    func testCancellationIsReturned() async {
+        let continuation = CancellingContinuation<String, Never>()
+
+        let task = Task { try await continuation.value }
+        task.cancel()
+
+        await XCTAssertThrowsError(
+            try await task.value,
+            of: CancellationError.self
+        )
+    }
+
+    func testResumeIsReturned() async {
+        let continuation = CancellingContinuation<Void, Error>()
+
+        let task = Task { try await continuation.value }
+        continuation.resume()
+
+        let result = await task.result
+        XCTAssertNoThrow(try result.get())
+    }
+
+    func testErrorIsReturned() async {
+        let continuation = CancellingContinuation<String, Error>()
+
+        let task = Task { try await continuation.value }
+        continuation.resume(throwing: SocketError.disconnected)
+
+        await XCTAssertThrowsError(
+            try await task.value,
+            of: SocketError.self
+        )
+    }
+}