add a simple unit test

Author: chelsea-lin

tests/unit/test_json.py

@@ -0,0 +1,34 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+import datetime as dt
+from typing import Optional
+
+import pandas
+import pandas.api.extensions
+import pandas.testing
+import pyarrow
+import pytest
+
+import packaging.version
+
+import db_dtypes
+
+is_supported_version = packaging.version.Version(pandas.__version__) >= packaging.version.Version("1.5.0")
+
+@pytest.mark.skipif(not is_supported_version, reason="requires Pandas 1.5.0 and above")
+def test_constructor_from_sequence():
+    json_obj = [0, "str", {"a": 0, "b": 1}]
+    data = db_dtypes.JSONArray._from_sequence(json_obj)