def test_add_column(self):
m = ConcreteModel()
m.x = Var(within=NonNegativeReals)
m.c = Constraint(expr=(0, m.x, 1))
m.obj = Objective(expr=-m.x)
opt = SolverFactory('cplex_persistent')
opt.set_instance(m)
opt.solve()
self.assertAlmostEqual(m.x.value, 1)
m.y = Var(within=NonNegativeReals)
opt.add_column(m, m.y, -3, [m.c], [2])
opt.solve()
self.assertAlmostEqual(m.x.value, 0)
self.assertAlmostEqual(m.y.value, 0.5)
