Added simple tldname regex test

This test was removed during a previous refactor.

Change-Id: Ief4d42625bc100d3a881163c684f86e010237f82

designate/tests/unit/common/test_regex.py

@@ -0,0 +1,42 @@
+# 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 oslotest.base
+
+from designate.common import constants
+
+
+class TestRegex(oslotest.base.BaseTestCase):
+    def setUp(self):
+        super(TestRegex, self).setUp()
+
+    def test_tldname_is_valid(self):
+        valid_tldnames = [
+            'com',
+            'net',
+            'org',
+            'co.uk',
+        ]
+
+        for tldname in valid_tldnames:
+            self.assertTrue(constants.RE_TLDNAME.match(tldname))
+
+    def test_tldname_is_not_valid(self):
+        invalid_tldnames = [
+            # Invalid Formats
+            'com.',
+            '.com',
+            # Trailing newline - Bug 1471158
+            "com\n",
+        ]
+
+        for tldname in invalid_tldnames:
+            self.assertFalse(constants.RE_TLDNAME.match(tldname))