public void TestActivateSystem_ActivateDeactivatedSystem_ActivatesGivenSystem()
{
var systemMock = Substitute.For <IUpdateSystem>();
Assert.DoesNotThrow(() =>
{
SystemId registeredSystemId = mSystemManager.RegisterSystem(systemMock);
SystemId deactivatedSystemId = mSystemManager.DeactivateSystem(registeredSystemId);
SystemId newSystemId = mSystemManager.ActivateSystem(registeredSystemId);
Assert.AreNotEqual(newSystemId, deactivatedSystemId);
});
}