public static void TestAddEntity()
{
Entity e1 = EnvironmentManager.AddEntity();
Assert.True(EnvironmentManager.EntityExists(e1));
Assert.True(e1.EntityExists());
Assert.AreEqual(e1, (Entity)1);
Entity e2 = EnvironmentManager.AddEntity();
Assert.True(EnvironmentManager.EntityExists(e2));
Assert.True(e2.EntityExists());
Assert.AreNotEqual(e1, e2);
}