multithreading - 如何对这些同步方法进行有效的单元测试？

Question

基于对 this question 的回答, 我对以下两种同步方法的简单性和易用性感到满意:

func synchronized(lock: AnyObject, closure: () -> Void) {
    objc_sync_enter(lock)
    closure()
    objc_sync_exit(lock)
}

func synchronized<T>(lock: AnyObject, closure: () -> T) -> T {
    objc_sync_enter(lock)
    defer { objc_sync_exit(lock) }
    return closure()
}

但为了确保它们确实在做我想做的事情，我想将它们包装在成堆的单元测试中。我如何编写单元测试来有效地测试这些方法(并显示它们实际上正在同步代码)？

理想情况下，我还希望这些单元测试尽可能简单明了。据推测，这个测试应该是这样的代码，如果在同步块(synchronized block)之外运行，将给出一组结果，但在这些同步块(synchronized block)内给出一组完全独立的结果。

Answer 1

这是一个可运行的 XCTest，用于验证同步。如果你同步 delayedAddToArray，它会工作，否则会失败。

class DelayedArray:NSObject {
    func synchronized(lock: AnyObject, closure: () -> Void) {
        objc_sync_enter(lock)
        closure()
        objc_sync_exit(lock)
    }

    private var array = [String]()
    func delayedAddToArray(expectation:XCTestExpectation) {
        synchronized(self) {
            let arrayCount = self.array.count
            self.array.append("hi")
            sleep(5)
            XCTAssert(self.array.count == arrayCount + 1)
            expectation.fulfill()
        }
    }
}

func testExample() {
    let expectation = self.expectationWithDescription("desc")
    let expectation2 = self.expectationWithDescription("desc2")

    let delayedArray:DelayedArray = DelayedArray()
    // This is an example of a functional test case.
    let thread = NSThread(target: delayedArray, selector: "delayedAddToArray:", object: expectation)
    let secondThread = NSThread(target: delayedArray, selector: "delayedAddToArray:", object: expectation2)
    thread.start()
    sleep(1)
    secondThread.start()

    self.waitForExpectationsWithTimeout(15, handler: nil)
}