Modularize inventory and add initial testing

The inventory module for bifrost is a vital component, however
as it was developed as a single file and it needs to to be broken
up into a modular chunk in order to have meaningful testing.

Broke into module, symlinking the file into place for now until
documentation and install process can be updated.

Added two basic tests to lay the groundwork for basic testing
of the data parsing and result passing.

Change-Id: I02e79b635202a7933ae641b9d27cc19a75b7bc4f
Partial-Bug: 1499801

bifrost/tests/unit/test_inventory.py

@@ -0,0 +1,41 @@
+# -*- coding: utf-8 -*-
+
+# 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.
+
+"""
+test_bifrost
+----------------------------------
+
+Tests for `bifrost` module.
+"""
+
+from bifrost import inventory
+from bifrost.tests import base
+
+
+class TestBifrostInventory(base.TestCase):
+
+    def test_inventory_preparation(self):
+        (groups, hostvars) = inventory._prepare_inventory()
+        self.assertIn("baremetal", groups)
+        self.assertIn("localhost", groups)
+        self.assertDictEqual(hostvars, {})
+        localhost_value = dict(hosts=["127.0.0.1"])
+        self.assertDictEqual(groups['localhost'], localhost_value)
+
+    def test__val_or_none(self):
+        array = ['no', '', 'yes']
+        self.assertEqual(inventory._val_or_none(array, 0), 'no')
+        self.assertEqual(inventory._val_or_none(array, 1), None)
+        self.assertEqual(inventory._val_or_none(array, 2), 'yes')
+        self.assertEqual(inventory._val_or_none(array, 4), None)