Mock the 'libvirt' import on tests

This patch is removing python-libvirt from test-requirements.txt and
mocking that library for the tests.

Closes-Bug: #1616906
Change-Id: Id067476c58bf9ddedd6cfc5fe80303f7d949cb9e

ironic_staging_drivers/libvirt/power.py

@@ -41,9 +41,9 @@ Currently supported transports are:
 import os
 import xml.etree.ElementTree as ET
 
-import libvirt
 from oslo_config import cfg
 from oslo_log import log as logging
+from oslo_utils import importutils
 
 from ironic.common import boot_devices
 from ironic.common import exception as ir_exc
@@ -54,6 +54,7 @@ from ironic.drivers import base
 from ironic.drivers import utils as driver_utils
 from ironic_staging_drivers.common import exception as isd_exc
 
+libvirt = importutils.try_import('libvirt')
 
 CONF = cfg.CONF
 

ironic_staging_drivers/tests/unit/third_party_driver_mock_specs.py

@@ -20,3 +20,12 @@ when needing to mock those third party modules"""
 IBOOT_SPEC = (
     'iBootInterface',
 )
+
+# libvirt
+LIBVIRT_SPEC = (
+    'libvirtError',
+    'open',
+    'openAuth',
+    'VIR_CRED_AUTHNAME',
+    'VIR_CRED_PASSPHRASE',
+)

ironic_staging_drivers/tests/unit/third_party_driver_mocks.py

@@ -47,3 +47,17 @@ if not iboot:
 # external library has been mocked
 if 'ironic.drivers.modules.iboot' in sys.modules:
     six.moves.reload_module(sys.modules['ironic.drivers.modules.iboot'])
+
+# attempt to load the external 'libvirt' library, which is required by
+# the optional drivers.modules.libvirt module
+libvirt = importutils.try_import('libvirt')
+if not libvirt:
+    lv = mock.MagicMock(spec_set=mock_specs.LIBVIRT_SPEC)
+    lv.libvirtError = Exception
+    sys.modules['libvirt'] = lv
+
+# if anything has loaded the libvirt driver yet, reload it now that the
+# external library has been mocked
+if 'ironic_staging_drivers.libvirt.power' in sys.modules:
+    six.moves.reload_module(
+        sys.modules['ironic_staging_drivers.libvirt.power'])

test-requirements.txt

@@ -16,6 +16,3 @@ testtools>=1.4.0 # MIT
 os-testr>=0.4.1 # Apache-2.0
 reno>=0.1.1 # Apache2
 mock>=1.2 # BSD
-
-# libvirt driver requires libvirt-python
-libvirt-python>=1.2.5 # LGPLv2+