def test_negative_update(self):
        c = CounterUpdateClause('a', 4, 7)
        c.set_context_id(3)

        self.assertEqual(c.get_context_size(), 1)
        self.assertEqual(str(c), '"a" = "a" - %(3)s')

        ctx = {}
        c.update_context(ctx)
        self.assertEqual(ctx, {'3': 3})
    def noop_update(self):
        c = CounterUpdateClause('a', 5, 5)
        c.set_context_id(5)

        self.assertEqual(c.get_context_size(), 1)
        self.assertEqual(str(c), '"a" = "a" + %(0)s')

        ctx = {}
        c.update_context(ctx)
        self.assertEqual(ctx, {'5': 0})
    def test_positive_update(self):
        c = CounterUpdateClause('a', 5, 3)
        c.set_context_id(5)

        self.assertEqual(c.get_context_size(), 1)
        self.assertEqual(str(c), '"a" = "a" + %(5)s')

        ctx = {}
        c.update_context(ctx)
        self.assertEqual(ctx, {'5': 2})