def test_variable_independence(self): model = Model() x = Variable('x', lb=0, ub=20) self.assertNotEqual(id(x), id(self.model.variables['x'])) y = Variable('y', lb=0, ub=10) constr = Constraint(1. * x + y, lb=3, name="constr1") model.add(constr) self.assertNotEqual(id(self.model.variables['x']), id(model.variables['x'])) self.assertNotEqual(id(self.model.variables['y']), id(model.variables['y'])) self.assertNotEqual(self.model.variables['y'].problem, model) self.assertNotEqual(self.model.variables['x'].problem, model) x.lb = -10 self.assertNotEqual(self.model.variables['x'].lb, model.variables['x'].lb)