//
// Copyright Amazon.com Inc. or its affiliates.
// All Rights Reserved.
//
// SPDX-License-Identifier: Apache-2.0
//

import XCTest
import Amplify

// As expected, running this work as straight up Task invocations:

// ```
// try await Task {
//     try await Task.sleep(nanoseconds: 1)
//     expectation1.fulfill()
// }
// try await Task {
//     try await Task.sleep(nanoseconds: 1)
//     expectation2.fulfill()
// }
// try await Task {
//     try await Task.sleep(nanoseconds: 1)
//     expectation3.fulfill()
// }
// await fulfillment(of: [expectation1, expectation2, expectation3], enforceOrder: true)
// ```
//
// does not guarantee order of execution. TaskQueue is intended to serialize execution to guarantee
// that the in-process task completes before the new one is executed.

final class AmplifyTaskQueueTests: XCTestCase {

    /// Test basic TaskQueue.sync behavior
    ///
    /// - Given: A task queue
    /// - When: I add tasks to the queue using the `sync` method
    /// - Then: The tasks execute in the order added
    func testSync() async throws {
        for _ in 1 ... 1_000 {
            try await doSyncTest()
        }
    }

    func doSyncTest() async throws {
        let expectation1 = expectation(description: "expectation1")
        let expectation2 = expectation(description: "expectation2")
        let expectation3 = expectation(description: "expectation3")

        let taskQueue = TaskQueue<Void>()
        try await taskQueue.sync {
            try await Task.sleep(nanoseconds: 1)
            expectation1.fulfill()
        }

        try await taskQueue.sync {
            try await Task.sleep(nanoseconds: 1)
            expectation2.fulfill()
        }

        try await taskQueue.sync {
            try await Task.sleep(nanoseconds: 1)
            expectation3.fulfill()
        }

        await fulfillment(of: [expectation1, expectation2, expectation3], enforceOrder: true)
    }

}