tools: finish 'qvm-volume revert' implementation, add tests

It wasn't aware of snapshot identifier, fix that. Also update to use
VM:VOLUME syntax, not POOL:VID.

qubesadmin/tests/tools/qvm_volume.py

@@ -179,3 +179,74 @@ class TC_00_qvm_volume(qubesadmin.tests.QubesTestCase):
                     app=self.app))
         self.assertIn('shrink not allowed', stderr.getvalue())
         self.assertAllCalled()
+
+    def test_020_revert(self):
+        self.app.expected_calls[('dom0', 'admin.vm.List', None, None)] = \
+            b'0\x00testvm class=AppVM state=Running\n'
+        self.app.expected_calls[
+            ('testvm', 'admin.vm.volume.List', None, None)] = \
+            b'0\x00root\nprivate\n'
+        self.app.expected_calls[
+            ('testvm', 'admin.vm.volume.ListSnapshots', 'private', None)] = \
+            b'0\x00200101010000\n200201010000\n200301010000\n'
+        self.app.expected_calls[
+            ('testvm', 'admin.vm.volume.Revert', 'private', b'200301010000')] = \
+            b'0\x00'
+        self.assertEqual(0,
+            qubesadmin.tools.qvm_volume.main(
+                ['revert', 'testvm:private'],
+                app=self.app))
+        self.assertAllCalled()
+
+    def test_021_revert_error(self):
+        self.app.expected_calls[('dom0', 'admin.vm.List', None, None)] = \
+            b'0\x00testvm class=AppVM state=Running\n'
+        self.app.expected_calls[
+            ('testvm', 'admin.vm.volume.List', None, None)] = \
+            b'0\x00root\nprivate\n'
+        self.app.expected_calls[
+            ('testvm', 'admin.vm.volume.ListSnapshots', 'private', None)] = \
+            b'0\x00200101010000\n200201010000\n200301010000\n'
+        self.app.expected_calls[
+            ('testvm', 'admin.vm.volume.Revert', 'private', b'200301010000')] = \
+            b'2\x00StoragePoolException\x00\x00Failed to revert volume: ' \
+            b'some error\x00'
+        with qubesadmin.tests.tools.StderrBuffer() as stderr:
+            self.assertEqual(1,
+                qubesadmin.tools.qvm_volume.main(
+                    ['revert', 'testvm:private'],
+                    app=self.app))
+        self.assertIn('some error', stderr.getvalue())
+        self.assertAllCalled()
+
+    def test_022_revert_no_snapshots(self):
+        self.app.expected_calls[('dom0', 'admin.vm.List', None, None)] = \
+            b'0\x00testvm class=AppVM state=Running\n'
+        self.app.expected_calls[
+            ('testvm', 'admin.vm.volume.List', None, None)] = \
+            b'0\x00root\nprivate\n'
+        self.app.expected_calls[
+            ('testvm', 'admin.vm.volume.ListSnapshots', 'private', None)] = \
+            b'0\x00'
+        with qubesadmin.tests.tools.StderrBuffer() as stderr:
+            self.assertEqual(1,
+                qubesadmin.tools.qvm_volume.main(
+                    ['revert', 'testvm:private'],
+                    app=self.app))
+        self.assertIn('No snapshots', stderr.getvalue())
+        self.assertAllCalled()
+
+    def test_023_revert_specific(self):
+        self.app.expected_calls[('dom0', 'admin.vm.List', None, None)] = \
+            b'0\x00testvm class=AppVM state=Running\n'
+        self.app.expected_calls[
+            ('testvm', 'admin.vm.volume.List', None, None)] = \
+            b'0\x00root\nprivate\n'
+        self.app.expected_calls[
+            ('testvm', 'admin.vm.volume.Revert', 'private', b'20050101')] = \
+            b'0\x00'
+        self.assertEqual(0,
+            qubesadmin.tools.qvm_volume.main(
+                ['revert', 'testvm:private', '20050101'],
+                app=self.app))
+        self.assertAllCalled()

qubesadmin/tools/qvm_volume.py

@@ -134,13 +134,16 @@ def list_volumes(args):
 def revert_volume(args):
     ''' Revert volume to previous state '''
     volume = args.volume
-    app = args.app
+    if args.revision:
-    try:
+        revision = args.revision
-        pool = app.pools[volume.pool]
+    else:
-        pool.revert(volume)
+        revisions = volume.revisions
-    except qubesadmin.exc.StoragePoolException as e:
+        if not revisions:
-        print(str(e), file=sys.stderr)
+            raise qubesadmin.exc.StoragePoolException(
-        sys.exit(1)
+                'No snapshots available')
+        revision = volume.revisions[-1]
+
+    volume.revert(revision)
 
 
 def extend_volumes(args):
@@ -177,6 +180,10 @@ def init_revert_parser(sub_parsers):
         help='revert volume to previous revision')
     revert_parser.add_argument(metavar='VM:VOLUME', dest='volume',
                                action=qubesadmin.tools.VMVolumeAction)
+    revert_parser.add_argument(metavar='REVISION', dest='revision',
+        help='Optional revision to revert to;'
+             'if not specified, latest one is assumed',
+        action='store', nargs='?')
     revert_parser.set_defaults(func=revert_volume)