测试在私有变量中保留其状态的类 [英] Testing a class which preserves its state in private variables

问题描述

我正在为我的班级编写单元测试.这个类在一些 private 变量(我不想公开)中保留它的状态.所以场景是:

I am writing unit tests for my class. This class preserves its state in some private variables (which I don't want to expose publicly). So the scenario is:

• 如果我调用一个方法，它会在第一次将这个状态保存在 private 属性中，并调用一个委托方法并得到一些结果.
• 当我第二次调用相同的方法时，输出将与之前的输入不同.

• If I call a method, the first time it will keep that state in private properties and call a delegate method with some result.
• When I call the same method a second time, the output will be different on the basis of the previous input.

我想在我的测试中涵盖所有情况.

I want to cover all the cases in my tests.

• 一种简单的方法是将我的私有属性更改为公共属性，以便我可以在单元测试中模拟之前的输入.
• 另一种方法是在同一个测试中使用不同的输入调用同一个方法两次.第一次调用将保持状态，而下一次调用将进行实际测试.

但这两种方式对我来说都很尴尬，我不确定哪种方式最好.为此类编写单元测试的最佳方法是什么?

But both these ways seem awkward to me, and I am not sure of the best one. What is the best way to write unit test for this class?

protocol ZoneUpdateDetectorOutput: class {
    func updateZoneState(_ state: ZoneState)
}

class ZoneUpdateDetector {
    var zoneChangeTimer: TimerProtocol?
    weak var delegate: ZoneUpdateDetectorOutput?

    private var previousZoneState: ZoneState?
    private var expectedZoneState: ZoneState?

    private func updateZoneState() {
        // If `expectedZoneState` is not equal to `previousZoneState` then `delegate` will be called
        // Otherwise it will just skip
        if expectedZoneState != previousZoneState {
            delegate?.updateZoneState(expectedZoneState!)
            previousZoneState = expectedZoneState
        }
    }

    private func runNotifyZoneStateTimer() {
        guard zoneChangeTimer?.isValid() == false else {
            return
        }
        zoneChangeTimer?.start(timeInterval: 5,
                               onFire: { [weak self] in
                                guard let strongSelf = self else {
                                    return
                                }
                                // On timer fire, it will try to update the state
                                strongSelf.updateZoneState()
        })
    }

    // When zone changes, this method is invoked
    // I basically want to test this method
    func zoneStateChanged(_ state: ZoneState) {
        expectedZoneState = state
        if state != .inZone {
            runNotifyZoneStateTimer()
        } else {
            zoneChangeTimer?.stop()
        }
    }
}

推荐答案

经过与一些专家的研究和讨论，我想出了一个解决方案，如果我们想测试一个保留其状态的类，那么保留其状态的功能状态应该属于一个单独的类.这与将变量设置为私有的目的相同.因此，ZoneUpdateDetector 应该有一个依赖项，例如:ZoneUpdateStatePreserver 并且它应该保持之前在 ZoneUpdateDetector

After researching and discussing with some experts, I come up with the solution that if we want to test a class which preserve it's state then the functionality which is preserving the state should go under a separate class. Which will serve the same purpose as setting the variables as private. So, ZoneUpdateDetector should have a dependency for example: ZoneUpdateStatePreserver and it should keep the state which was previously inside ZoneUpdateDetector

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