Xcode XCTest：如何嵌套异步调用（又称“如何避免XCTest API冲突”）

我觉得我有一个很常见的问题，但不知何故错过了关于最佳实践的备忘录。我想知道如何在XCTest中嵌套异步调用

我正试图通过基于Alamofire的RESTAPI在XCTest中测试/清理一些记录。我首先执行get，然后当完成处理程序启动时，我尝试循环返回的记录，对每个记录调用异步删除

第一个/明显的问题是，如果我使用XTest Expections，我会得到一个错误，因为我必须在初始外部get之后等待，然后尝试必须等待后续的删除调用，所以我无法为删除创建Expection，因为此时我正在等待get完成：

func deleteAllFoos() {

    let expectation = expectationWithDescription("deleteAllFoos")

    var foos:[Foo]!
    Api.foos({ i, f in
        foos?.append(f) },

        count: { c in
            foos = [Foo]()
            return c },

        success: { [unowned self] in

            for f in foos {

                let deleteExpectation = self.expectationWithDescription("\(f.id)")

                Api.fooDelete(f,
                    success: {
                        deleteExpectation.fulfill()
                    },
                    failure: { error in
                        XCTFail("deleteFoo failed")
                        deleteExpectation.fulfill()
                })
            }
            expectation.fulfill()
        },

        failure: { e in
            expectation.fulfill()
    })

    waitForExpectationsWithTimeout(300.0) { (error) in
        if error != nil {
            XCTFail(error.localizedDescription)
        }
    }
}

感觉上我也需要混合使用

nsrunlop/runMode

，但在安装和拆卸之外，这会锁定我。我确实在某一点上通过了底层的Alamofire代码，我想在这种情况下它会遇到阻塞问题（但这只是一个单元测试，所以这不是一个有意义的问题）

---

谢谢

不管它值多少钱，我最终在这里找到了一个很好的参考：

要点是，您可以使用GCD

dispatch\u group\t

创建一个基本测试类，如下所示：

class XCTestAsyncTest: XCTestCase {

    static var dispatchGroup:dispatch_group_t = dispatch_group_create()

    static func waitForGroup()
    {
        var didComplete = false;
        dispatch_group_notify(self.dispatchGroup, dispatch_get_main_queue(), {
            didComplete = true
        })

        while !didComplete {
            NSRunLoop.currentRunLoop().runMode(NSDefaultRunLoopMode,
                beforeDate: (NSDate.distantFuture() as? NSDate)!)
        }
    }
}

static func initializeData() {

    var nora = Student()
    nora.first = "Nora"
    nora.last = "Norris"
    nora.gender = .Female
    createStudentAsync(&nora)

    var mary = Student()
    mary.first = "Mary"
    mary.last = "Morison"
    mary.gender = .Female
    createStudentAsync(&mary)

    waitForGroup()

    // populate Mary
    var mm1 = createCourseAsync(mary, text: "Mary's first class")
    addCourse(&mm1)
    var mm2 = createCourse(mary, text: "Mary's second class")
    addCourse(&mm1)
    var mm3 = createCourse(mary, text: "Mary's third class")
    addCourse(&mm1)

    waitForGroup()

    ...

因此，您可以编写类似以下（人为）示例的帮助器测试函数：

这样称呼它：

class XCTestAsyncTest: XCTestCase {

    static var dispatchGroup:dispatch_group_t = dispatch_group_create()

    static func waitForGroup()
    {
        var didComplete = false;
        dispatch_group_notify(self.dispatchGroup, dispatch_get_main_queue(), {
            didComplete = true
        })

        while !didComplete {
            NSRunLoop.currentRunLoop().runMode(NSDefaultRunLoopMode,
                beforeDate: (NSDate.distantFuture() as? NSDate)!)
        }
    }
}

static func initializeData() {

    var nora = Student()
    nora.first = "Nora"
    nora.last = "Norris"
    nora.gender = .Female
    createStudentAsync(&nora)

    var mary = Student()
    mary.first = "Mary"
    mary.last = "Morison"
    mary.gender = .Female
    createStudentAsync(&mary)

    waitForGroup()

    // populate Mary
    var mm1 = createCourseAsync(mary, text: "Mary's first class")
    addCourse(&mm1)
    var mm2 = createCourse(mary, text: "Mary's second class")
    addCourse(&mm1)
    var mm3 = createCourse(mary, text: "Mary's third class")
    addCourse(&mm1)

    waitForGroup()

    ...

这在我的测试中是简单而有效的