Add a test_mocks to mock charmhelpers centrally

Every reactive charm that uses charms.openstack and implements
unit testing needs to mock charmhelpers, as otherwise the tests
blow up.  This patch centralises the mocking of charmhelpers to
charms.openstack so that a charm layer can just import test_mocks
and charmhelpers will be mocked out along with setting up a default
charmhelpers.c.o.u.OPENSTACK_RELEASES so that when an OpenStackCharm()
derived charm class won't fail on definition.

Closes-Bug: #1693017
Change-Id: I5ac40617ee30e5f421ec16fc7592177a5e6aa166

charms_openstack/test_mocks.py

@@ -0,0 +1,54 @@
+import sys
+import mock
+
+charmhelpers = None
+apt_pkg = None
+
+
+def mock_charmhelpers():
+    # Mock out charmhelpers so that we can test without it.
+    # also stops sideeffects from occuring.
+    global charmhelpers
+    global apt_pkg
+    charmhelpers = mock.MagicMock()
+    apt_pkg = mock.MagicMock()
+    sys.modules['apt_pkg'] = apt_pkg
+    sys.modules['charmhelpers'] = charmhelpers
+    sys.modules['charmhelpers.core'] = charmhelpers.core
+    sys.modules['charmhelpers.core.hookenv'] = charmhelpers.core.hookenv
+    sys.modules['charmhelpers.core.host'] = charmhelpers.core.host
+    sys.modules['charmhelpers.core.unitdata'] = charmhelpers.core.unitdata
+    sys.modules['charmhelpers.core.templating'] = charmhelpers.core.templating
+    sys.modules['charmhelpers.contrib'] = charmhelpers.contrib
+    sys.modules['charmhelpers.contrib.openstack'] = (
+        charmhelpers.contrib.openstack)
+    sys.modules['charmhelpers.contrib.openstack.utils'] = (
+        charmhelpers.contrib.openstack.utils)
+    sys.modules['charmhelpers.contrib.openstack.templating'] = (
+        charmhelpers.contrib.openstack.templating)
+    sys.modules['charmhelpers.contrib.network'] = charmhelpers.contrib.network
+    sys.modules['charmhelpers.contrib.network.ip'] = (
+        charmhelpers.contrib.network.ip)
+    sys.modules['charmhelpers.fetch'] = charmhelpers.fetch
+    sys.modules['charmhelpers.cli'] = charmhelpers.cli
+    sys.modules['charmhelpers.contrib.hahelpers'] = (
+        charmhelpers.contrib.hahelpers)
+    sys.modules['charmhelpers.contrib.hahelpers.cluster'] = (
+        charmhelpers.contrib.hahelpers.cluster)
+
+    # mock in the openstack releases so that the tests can run
+    charmhelpers.contrib.openstack.utils.OPENSTACK_RELEASES = (
+        'diablo',
+        'essex',
+        'folsom',
+        'grizzly',
+        'havana',
+        'icehouse',
+        'juno',
+        'kilo',
+        'liberty',
+        'mitaka',
+        'newton',
+        'ocata',
+        'pike',
+    )