[PATCH RFC 29/32] python//qtest.py: Check before accessing _qtest

[John Snow]

It can be None; so add assertions or exceptions where appropriate to
guard the access accordingly.

Signed-off-by: John Snow <address@hidden>
---
 python/qemu/lib/qtest.py | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/python/qemu/lib/qtest.py b/python/qemu/lib/qtest.py
index a8be0c782f..05c63a1d58 100644
--- a/python/qemu/lib/qtest.py
+++ b/python/qemu/lib/qtest.py
@@ -126,7 +126,8 @@ def _pre_launch(self):
         super()._pre_launch()
         self._qtest = QEMUQtestProtocol(self._qtest_path, server=True)
 
-    def _post_launch(self):
+    def _post_launch(self) -> None:
+        assert self._qtest is not None
         super()._post_launch()
         self._qtest.accept()
 
@@ -134,6 +135,13 @@ def _post_shutdown(self):
         super()._post_shutdown()
         self._remove_if_exists(self._qtest_path)
 
-    def qtest(self, cmd):
-        '''Send a qtest command to guest'''
+    def qtest(self, cmd: str) -> str:
+        """
+        Send a qtest command to the guest.
+
+        :param cmd: qtest command to send
+        :return: qtest server response
+        """
+        if self._qtest is None:
+            raise RuntimeError("qtest socket not available")
         return self._qtest.cmd(cmd)
-- 
2.21.1