[PULL 13/14] iotests.py: Let wait_migration() return on failure

[Eric Blake <eblake@redhat.com>]

From: Max Reitz <mreitz@redhat.com>

Let wait_migration() return on failure (with the return value indicating
whether the migration was completed or has failed), so we can use it for
migrations that are expected to fail, too.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20200820150725.68687-3-mreitz@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 tests/qemu-iotests/iotests.py | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index 717b5b652c45..e197c73ca501 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -729,16 +729,22 @@ class VM(qtest.QEMUQtestMachine):
             }
         ]))

-    def wait_migration(self, expect_runstate):
+    def wait_migration(self, expect_runstate: Optional[str]) -> bool:
         while True:
             event = self.event_wait('MIGRATION')
             log(event, filters=[filter_qmp_event])
-            if event['data']['status'] == 'completed':
+            if event['data']['status'] in ('completed', 'failed'):
                 break
-        # The event may occur in finish-migrate, so wait for the expected
-        # post-migration runstate
-        while self.qmp('query-status')['return']['status'] != expect_runstate:
-            pass
+
+        if event['data']['status'] == 'completed':
+            # The event may occur in finish-migrate, so wait for the expected
+            # post-migration runstate
+            runstate = None
+            while runstate != expect_runstate:
+                runstate = self.qmp('query-status')['return']['status']
+            return True
+        else:
+            return False

     def node_info(self, node_name):
         nodes = self.qmp('query-named-block-nodes')
-- 
2.28.0