Add test for Extension array with generic ExtensionType

Author: AlenkaF

python/pyarrow/tests/test_extension_type.py

@@ -867,11 +867,29 @@ def test_generic_ext_type_equality():
     assert not period_type == period_type3
 
 
-def test_generic_ext_type_pickling():
+def test_generic_ext_type_pickling(registered_period_type):
     # GH-36038
-    period_type = PeriodType('D')
-    period_type_pickled = pickle.loads(pickle.dumps(period_type))
-    assert period_type == period_type_pickled
+    for proto in range(0, pickle.HIGHEST_PROTOCOL + 1):
+        period_type, _ = registered_period_type
+        ser = pickle.dumps(period_type, protocol=proto)
+        period_type_pickled = pickle.loads(ser)
+        assert period_type == period_type_pickled
+
+
+def test_generic_ext_array_pickling(registered_period_type):
+    for proto in range(0, pickle.HIGHEST_PROTOCOL + 1):
+        period_type, _ = registered_period_type
+        storage = pa.array([1, 2, 3, 4], pa.int64())
+        arr = pa.ExtensionArray.from_storage(period_type, storage)
+        ser = pickle.dumps(arr, protocol=proto)
+        del storage, arr
+        arr = pickle.loads(ser)
+        arr.validate()
+        assert isinstance(arr, pa.ExtensionArray)
+        assert arr.type == period_type
+        assert arr.type.storage_type == pa.int64()
+        assert arr.storage.type == pa.int64()
+        assert arr.storage.to_pylist() == [1, 2, 3, 4]
 
 
 def test_generic_ext_type_register(registered_period_type):