add more unit coverage

@@ -138,6 +138,24 @@ def test_from_api_repr(self):
 self.assertEqual(field.fields[0].field_type, "INTEGER")
 self.assertEqual(field.fields[0].mode, "NULLABLE")
 
+def test_from_api_repr_policy(self):
+field = self._get_target_class().from_api_repr(
+{
+"fields": [{"mode": "nullable", "name": "bar", "type": "integer"}],
+"name": "foo",
+"type": "record",
+"policyTags": ("one", "two"),
+}
+)
+self.assertEqual(field.name, "foo")
+self.assertEqual(field.field_type, "RECORD")
+self.assertEqual(field.description, "test_description")
+self.assertEqual(len(field.fields), 1)
+self.assertEqual(field.fields[0].name, "bar")
+self.assertEqual(field.fields[0].field_type, "INTEGER")
+self.assertEqual(field.fields[0].mode, "NULLABLE")
+self.assertEqual(field.policy_tags, ("one", "two"))
+
 def test_from_api_repr_defaults(self):
 field = self._get_target_class().from_api_repr(
 {"name": "foo", "type": "record"}
@@ -659,3 +677,27 @@ def test_valid_mapping_representation(self):
 
 result = self._call_fut(schema)
 self.assertEqual(result, expected_schema)
+
+
+class TestPolicyTags(unittest.TestCase):
+@staticmethod
+def _get_target_class():
+from google.cloud.bigquery.schema import PolicyTagList
+
+return PolicyTagList
+
+def _make_one(self, *args, **kw):
+return self._get_target_class()(*args, **kw)
+
+def test_constructor(self):
+empty_policy_tags = self._make_one()
+self.assertIsNotNone(empty_policy_tags.names)
+self.assertEqual(len(empty_policy_tags.names), 0)
+policy_tags = self._make_one(("foo", "bar"))
+self.assertEqual(policy_tags.names, ("foo", "bar"))
+
+def test_from_api_repr(self):
+klass = self._get_target_class()
+api_repr = {"names": ("foo")}
+policy_tags = klass.from_api_repr(api_repr)
+self.assertEqual(policy_tags.to_api_repr(), api_repr)