Add test coverage for nova.privsep.qemu.

Now that we have a fixture that makes this easier, pay down some
technical debt.

Change-Id: I74491ecce3527fe375d219f5c6bc87123f796c44

2 files changed, 56 insertions, 0 deletions

diff --git a/nova/privsep/qemu.py b/nova/privsep/qemu.py
index 8c22d689cb..5880fb1775 100644
--- a/nova/privsep/qemu.py
+++ b/nova/privsep/qemu.py
@@ -55,6 +55,8 @@ def unprivileged_convert_image(source, dest, in_format, out_format,
     # just like 'writethrough', calls fsync(2)|fdatasync(2), which
     # ensures to safely write the data to the physical disk.
 
+    # NOTE(mikal): there is an assumption here that the source and destination
+    # are in the instances_path. Is that worth enforcing?
     if nova.privsep.utils.supports_direct_io(instances_path):
         cache_mode = 'none'
     else:
diff --git a/nova/tests/unit/privsep/test_qemu.py b/nova/tests/unit/privsep/test_qemu.py
new file mode 100644
index 0000000000..5fbc178983
--- /dev/null
+++ b/nova/tests/unit/privsep/test_qemu.py
@@ -0,0 +1,54 @@
+# Copyright 2019 Aptira Pty Ltd
+# All Rights Reserved.
+#
+#    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 mock
+
+import nova.privsep.qemu
+from nova import test
+from nova.tests import fixtures
+
+
+class QemuTestCase(test.NoDBTestCase):
+    """Test qemu related utility methods."""
+
+    def setUp(self):
+        super(QemuTestCase, self).setUp()
+        self.useFixture(fixtures.PrivsepFixture())
+
+    @mock.patch('oslo_concurrency.processutils.execute')
+    @mock.patch('nova.privsep.utils.supports_direct_io')
+    def _test_convert_image(self, meth, mock_supports_direct_io, mock_execute):
+        mock_supports_direct_io.return_value = True
+        meth('/fake/source', '/fake/destination', 'informat', 'outformat',
+             '/fake/instances/path', compress=True)
+        mock_execute.assert_called_with(
+            'qemu-img', 'convert', '-t', 'none', '-O', 'outformat',
+            '-f', 'informat', '-c', '/fake/source', '/fake/destination')
+
+        mock_supports_direct_io.reset_mock()
+        mock_execute.reset_mock()
+
+        mock_supports_direct_io.return_value = False
+        meth('/fake/source', '/fake/destination', 'informat', 'outformat',
+             '/fake/instances/path', compress=True)
+        mock_execute.assert_called_with(
+            'qemu-img', 'convert', '-t', 'writeback', '-O', 'outformat',
+            '-f', 'informat', '-c', '/fake/source', '/fake/destination')
+
+    def test_convert_image(self):
+        self._test_convert_image(nova.privsep.qemu.convert_image)
+
+    def test_convert_image_unprivileged(self):
+        self._test_convert_image(nova.privsep.qemu.unprivileged_convert_image)