tests: added isolanguage test

tests/test_isolanguage.py

@@ -0,0 +1,32 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright (C) 2016-2020 CERN.
+#
+# Marshmallow-Utils is free software; you can redistribute it and/or modify
+# it under the terms of the MIT License; see LICENSE file for more details.
+
+"""Test the marshmallow ISO Language."""
+
+import pytest
+from marshmallow import Schema, ValidationError
+
+from marshmallow_utils.fields import ISOLangString
+
+
+def test_iso639_3_assert():
+    class MySchema(Schema):
+        f = ISOLangString()
+
+    assert MySchema().load({'f': "tes"}) == {'f': "tes"}
+
+
+test_data = ["te", "12t", "te!", ",te!"]
+
+
+@pytest.mark.parametrize('test_input', test_data)
+def test_iso639_3_raise(test_input):
+    class MySchema(Schema):
+        f = ISOLangString()
+
+    for i in test_data:
+        pytest.raises(ValidationError, MySchema().load, {'f': i})