fun `can load state after capturing`() {
        tracker.systemPropertyRemoved("some.property")
        tracker.getCachedState()

        tracker.loadFrom(emptyEnvironmentState())
    }

    @Test(expected = IllegalStateException::class)
    fun `updating state after loading throws`() {
        tracker.loadFrom(emptyEnvironmentState())

        tracker.systemPropertyRemoved("some.property")
    }

    fun loadFrom(storedState: CachedEnvironmentState) = mode.toRestoringMode().loadFrom(storedState)

    fun getCachedState() = mode.toTrackingMode().getCachedState()

    fun systemPropertyRemoved(key: Any) = mode.toTrackingMode().systemPropertyRemoved(key)

    fun systemPropertiesCleared() = mode.toTrackingMode().systemPropertiesCleared()

    private
    inner class ModeHolder {

        environmentChangeTracker.systemPropertyChanged(key, value, consumer)
    }

    override fun systemPropertyRemoved(key: Any, consumer: String) {
        environmentChangeTracker.systemPropertyRemoved(key)
    }

    override fun systemPropertiesCleared(consumer: String) {
        environmentChangeTracker.systemPropertiesCleared()
    }