public void StartAndStopAreNotReentrant()
{
using var mkw = new ModifierKeysWatcher(new NativeMethodsMock());
bool IsRunning() => mkw.GetPrivateField <bool>("_running");
Assert.False(IsRunning());
mkw.Start();
Assert.True(IsRunning());
mkw.Start();
Assert.True(IsRunning());
mkw.Stop();
Assert.False(IsRunning());
mkw.Stop();
Assert.False(IsRunning());
}