'Test string representations.'

def test_str(self):

    obj = Minimize(self.x)
    self.assertEqual(repr(obj), ('Minimize(%s)' % repr(self.x)))
    obj = Minimize((2 * self.x))
    self.assertEqual(repr(obj), ('Minimize(%s)' % repr((2 * self.x))))
    obj = Maximize(self.x)
    self.assertEqual(repr(obj), ('Maximize(%s)' % repr(self.x)))
    obj = Maximize((2 * self.x))
    self.assertEqual(repr(obj), ('Maximize(%s)' % repr((2 * self.x))))
