test: Introduce new protocols flavor property "client_error_exception_type".

This allows the tests to check for more specific exceptions and in turn fixes the pylint error that the "except" is too broad.

test/gorpc_protocols_flavor.py

@@ -1,4 +1,7 @@
 #!/usr/bin/env python
+"""Defines which protocols to use for the Go (BSON) RPC flavor."""
+
+from net import gorpc
 
 import protocols_flavor
 
@@ -39,6 +42,9 @@ class GoRpcProtocolsFlavor(protocols_flavor.ProtocolsFlavor):
   def vtgate_python_protocol(self):
     return 'gorpc'
 
+  def client_error_exception_type(self):
+    return gorpc.AppError
+
   def rpc_timeout_message(self):
     return 'context deadline exceeded'
 

test/grpc_protocols_flavor.py

@@ -1,4 +1,7 @@
 #!/usr/bin/env python
+"""Defines which protocols to use for the gRPC flavor."""
+
+from grpc.framework.interfaces.face import face
 
 import protocols_flavor
 
@@ -36,6 +39,9 @@ class GRpcProtocolsFlavor(protocols_flavor.ProtocolsFlavor):
   def vtgate_python_protocol(self):
     return 'gorpc'
 
+  def client_error_exception_type(self):
+    return face.RemoteError
+
   def rpc_timeout_message(self):
     return 'context deadline exceeded'
 

test/protocols_flavor.py

@@ -56,6 +56,10 @@ class ProtocolsFlavor(object):
     """The protocol to use to talk to vtgate with python clients."""
     raise NotImplementedError('Not implemented in the base class')
 
+  def client_error_exception_type(self):
+    """The exception type the RPC client implementation returns for errors."""
+    raise NotImplementedError('Not implemented in the base class')
+
   def rpc_timeout_message(self):
     """The error message used by the protocol to indicate a timeout."""
     raise NotImplementedError('Not implemented in the base class')
@@ -69,29 +73,29 @@ class ProtocolsFlavor(object):
     raise NotImplementedError('Not implemented in the base class')
 
 
-__knows_protocols_flavor_map = {}
-__protocols_flavor = None
+_knows_protocols_flavor_map = {}
+_protocols_flavor = None
 
 
 def protocols_flavor():
-  return __protocols_flavor
+  return _protocols_flavor
 
 
 def set_protocols_flavor(flavor):
   """Set the protocols flavor by flavor name."""
-  global __protocols_flavor
+  global _protocols_flavor
 
   if not flavor:
     flavor = 'gorpc'
 
-  cls = __knows_protocols_flavor_map.get(flavor, None)
+  cls = _knows_protocols_flavor_map.get(flavor, None)
   if not cls:
     logging.error('Unknown protocols flavor %s', flavor)
     exit(1)
-  __protocols_flavor = cls()
+  _protocols_flavor = cls()
 
   logging.debug('Using protocols flavor %s', flavor)
 
 
 def register_flavor(key, cls):
-  __knows_protocols_flavor_map[key] = cls
+  _knows_protocols_flavor_map[key] = cls

test/tabletmanager.py

@@ -391,7 +391,7 @@ class TestTabletManager(unittest.TestCase):
       try:
         utils.run_vtctl_json(['GetEndPoints', 'test_nj', 'test_keyspace/0',
                               'replica'])
-      except:
+      except protocols_flavor().client_error_exception_type():
         logging.debug('Tablet is gone from serving graph, good')
         break
       timeout = utils.wait_step(

test/update_stream.py

@@ -11,6 +11,7 @@ import utils
 from vtdb import dbexceptions
 from vtdb import update_stream
 from mysql_flavor import mysql_flavor
+from protocols_flavor import protocols_flavor
 
 master_tablet = tablet.Tablet()
 replica_tablet = tablet.Tablet()
@@ -102,7 +103,7 @@ def setUpModule():
         master_tablet.execute('select count(1) from vt_insert_test')
         replica_tablet.execute('select count(1) from vt_insert_test')
         break
-      except:
+      except protocols_flavor().client_error_exception_type():
         logging.exception('query failed')
         timeout = utils.wait_step('slave tablet having correct schema', timeout)
         # also re-run ReloadSchema on slave, it case the first one