Signed-off-by: William José Moreno Reyes <williamjmorenor@gmail.com>

Add a test to check correct error raises

This is a simple test to check that NotImplementedError raises
fine. This also should improve test code coverage.

tests/test_errors.py

@@ -0,0 +1,29 @@
+# -*- coding: utf-8 -*-
+# Copyright (c) 2003, Taro Ogawa.  All Rights Reserved.
+# Copyright (c) 2013, Savoir-faire Linux inc.  All Rights Reserved.
+
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+# Lesser General Public License for more details.
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+# MA 02110-1301 USA
+
+from __future__ import unicode_literals
+
+from unittest import TestCase
+
+from num2words import num2words
+
+
+class Num2WordsErrorsTest(TestCase):
+
+    def test_NotImplementedError(self):
+        with self.assertRaises(NotImplementedError):
+            num2words(100, lang="lalala")