Added UnexpectedServiceCallError exception

src/roswire/exceptions.py

@@ -6,6 +6,30 @@ class ROSWireException(Exception):
     """Base class used by all ROSWire exceptions."""
 
 
+@_attr.s(frozen=True, auto_exc=True, auto_attribs=True)
+class UnexpectedServiceCallError(ROSWireException):
+    """An unexpected error occurred during a service call.
+
+    Attributes
+    ----------
+    service_name: str
+        The name of the service that was called.
+    retcode: int
+        The return code that was produced by rosservice.
+    output: str
+        The output that was produced by rosservice
+    """
+    service_name: str
+    retcode: int
+    output: str
+
+    def __str__(self) -> str:
+        m = (f"Unexpected exit code [{self.retcode}] occurred "
+             f" during call to service [{self.service_name}]. "
+             f"Produced output: \"{self.output}\"")
+        return m
+
+
 class FailedToParseLaunchFile(ROSWireException):
     """An attempt to parse a launch file failed."""
 

src/roswire/proxy/service.py

@@ -13,6 +13,7 @@
 
 from .shell import ShellProxy
 from .. import exceptions
+from ..exceptions import UnexpectedServiceCallError
 from ..definitions import Message, SrvFormat, MsgFormat
 from ..description import SystemDescription
 
@@ -51,6 +52,13 @@ def call(self, message: Optional[Message] = None) -> Optional[Message]:
         -------
         Optional[Message]
             The reply produced by the service, if any.
+
+        Raises
+        ------
+        ROSWireException
+            If illegal arguments are provided to the service call.
+        UnexpectedServiceCallError
+            If an unexpected error occurred during the service call.
         """
         if not message:
             yml = '{}'
@@ -62,7 +70,9 @@ def call(self, message: Optional[Message] = None) -> Optional[Message]:
         if code == 2:
             raise exceptions.ROSWireException('illegal service call args')
         if code != 0:
-            raise exceptions.ROSWireException('unexpected error during service call')  # noqa
+            raise UnexpectedServiceCallError(service_name=self.name,
+                                             retcode=code,
+                                             output=output)
 
         fmt_response: Optional[MsgFormat] = self.format.response
         if not fmt_response: