python: backport 'Change error classes to have better repr methods'

By passing all of the arguments to the base class and overriding the
__str__ method when we want a different "human readable" message that
isn't just printing the list of arguments, we can ensure that all custom
error classes have a reasonable __repr__ implementation.

In the case of ExecuteError, the pseudo-field that isn't actually
correlated to an input argument can be re-imagined as a read-only
property; this forces consistency in the class and makes the repr output
more obviously correct.

Signed-off-by: John Snow <jsnow@redhat.com>
cherry picked from commit python-qemu-qmp@afdb7893f3b34212da4259b7202973f9a8cb85b3
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

1 files changed, 13 insertions, 7 deletions

diff --git a/python/qemu/qmp/qmp_client.py b/python/qemu/qmp/qmp_client.py
index 2a817f9db3..a87fb565ab 100644
--- a/python/qemu/qmp/qmp_client.py
+++ b/python/qemu/qmp/qmp_client.py
@@ -41,7 +41,7 @@ class _WrappedProtocolError(ProtocolError):
     :param exc: The root-cause exception.
     """
     def __init__(self, error_message: str, exc: Exception):
-        super().__init__(error_message)
+        super().__init__(error_message, exc)
         self.exc = exc
 
     def __str__(self) -> str:
@@ -76,15 +76,21 @@ class ExecuteError(QMPError):
     """
     def __init__(self, error_response: ErrorResponse,
                  sent: Message, received: Message):
-        super().__init__(error_response.error.desc)
+        super().__init__(error_response, sent, received)
         #: The sent `Message` that caused the failure
         self.sent: Message = sent
         #: The received `Message` that indicated failure
         self.received: Message = received
         #: The parsed error response
         self.error: ErrorResponse = error_response
-        #: The QMP error class
-        self.error_class: str = error_response.error.class_
+
+    @property
+    def error_class(self) -> str:
+        """The QMP error class"""
+        return self.error.error.class_
+
+    def __str__(self) -> str:
+        return self.error.error.desc
 
 
 class ExecInterruptedError(QMPError):
@@ -110,8 +116,8 @@ class _MsgProtocolError(ProtocolError):
     :param error_message: Human-readable string describing the error.
     :param msg: The QMP `Message` that caused the error.
     """
-    def __init__(self, error_message: str, msg: Message):
-        super().__init__(error_message)
+    def __init__(self, error_message: str, msg: Message, *args: object):
+        super().__init__(error_message, msg, *args)
         #: The received `Message` that caused the error.
         self.msg: Message = msg
 
@@ -150,7 +156,7 @@ class BadReplyError(_MsgProtocolError):
     :param sent: The message that was sent that prompted the error.
     """
     def __init__(self, error_message: str, msg: Message, sent: Message):
-        super().__init__(error_message, msg)
+        super().__init__(error_message, msg, sent)
         #: The sent `Message` that caused the failure
         self.sent = sent