def test_merge_by_id_no_items(self):
        schema = {
            "mergeStrategy": "arrayMergeById",
            "mergeOptions": {"idRef": "id"},
        }

        a = [
            {"id": "A", "field": 1},
        ]

        b = [
            {"id": "A", "field": 2},
        ]

        # by default, it should fall back to "replace" strategy for integers.
        expected = [
            {"id": "A", "field": 2},
        ]

        merger = jsonmerge.Merger(schema)

        base = None
        base = merger.merge(base, a)
        base = merger.merge(base, b)

        self.assertEqual(base, expected)