Fix pylint errors (raise-missing-from)

Change-Id: I02a00ed6b3611606785a3521361bf88705d42e07

tobiko/common/_exception.py

@@ -65,9 +65,9 @@ class TobikoException(Exception):
     def __getattr__(self, name):
         try:
             return self._properties[name]
-        except KeyError:
-            msg = ("{!r} object has no attribute {!r}").format(self, name)
-            raise AttributeError(msg)
+        except KeyError as ex:
+            raise AttributeError(f"{self!r} object has no attribute "
+                                 f"'{name}'") from ex
 
     def __repr__(self):
         return "{class_name}({message!r})".format(

tobiko/common/_testcase.py

@@ -16,7 +16,7 @@ from __future__ import absolute_import
 import logging
 import os
 import sys
-import typing
+import typing  # noqa
 
 from oslo_log import log
 from stestr import config_file
@@ -112,10 +112,9 @@ class TestCasesFinder(object):
                 ids = cmd.list_tests()
             else:
                 ids = cmd.test_ids
-        except SystemExit:
-            msg = ("Error discovering test cases IDs with parameters: "
-                   "{!r}").format(params)
-            raise RuntimeError(msg)
+        except SystemExit as ex:
+            raise RuntimeError("Error discovering test cases IDs with "
+                               f"parameters: {params}") from ex
         finally:
             cmd.cleanUp()
 

tobiko/http/_connection.py

@@ -45,17 +45,14 @@ class HTTPConnection(connection.HTTPConnection):
             conn = connection.connection.create_connection(
                 address, self.timeout, **extra_kw)
 
-        except connection.SocketTimeout:
+        except connection.SocketTimeout as ex:
             raise connection.ConnectTimeoutError(
-                self,
-                "Connection to %s timed out. (connect timeout=%s)"
-                % (self.host, self.timeout),
-            )
+                self, (f"Connection to {self.host} timed out. "
+                       f"(connect timeout={self.timeout})")) from ex
 
-        except connection.SocketError as e:
+        except connection.SocketError as ex:
             raise connection.NewConnectionError(
-                self, "Failed to establish a new connection: %s" % e
-            )
+                self, f"Failed to establish a new connection: {ex}") from ex
 
         return conn
 

tobiko/openstack/neutron/_client.py

@@ -139,29 +139,29 @@ def get_network(network, client=None, **params):
     try:
         return neutron_client(client).show_network(network,
                                                    **params)['network']
-    except neutronclient.exceptions.NotFound:
-        raise NoSuchNetwork(id=network)
+    except neutronclient.exceptions.NotFound as ex:
+        raise NoSuchNetwork(id=network) from ex
 
 
 def get_port(port, client=None, **params):
     try:
         return neutron_client(client).show_port(port, **params)['port']
-    except neutronclient.exceptions.NotFound:
-        raise NoSuchPort(id=port)
+    except neutronclient.exceptions.NotFound as ex:
+        raise NoSuchPort(id=port) from ex
 
 
 def get_router(router, client=None, **params):
     try:
         return neutron_client(client).show_router(router, **params)['router']
-    except neutronclient.exceptions.NotFound:
-        raise NoSuchRouter(id=router)
+    except neutronclient.exceptions.NotFound as ex:
+        raise NoSuchRouter(id=router) from ex
 
 
 def get_subnet(subnet, client=None, **params):
     try:
         return neutron_client(client).show_subnet(subnet, **params)['subnet']
-    except neutronclient.exceptions.NotFound:
-        raise NoSuchSubnet(id=subnet)
+    except neutronclient.exceptions.NotFound as ex:
+        raise NoSuchSubnet(id=subnet) from ex
 
 
 def list_l3_agent_hosting_routers(router, client=None, **params):

tobiko/openstack/nova/_server.py

@@ -60,10 +60,9 @@ def check_server_ip_address(address, ip_version=None, address_type=None):
         try:
             if address_type != address['OS-EXT-IPS:type']:
                 return False
-        except KeyError:
-            message = ("Unable to get IP type from server address {!r}"
-                       ).format(address)
-            raise ValueError(message)
+        except KeyError as ex:
+            raise ValueError("Unable to get IP type from server address "
+                             f"'{address}'") from ex
 
     return True
 

tobiko/openstack/stacks/_neutron.py

@@ -269,13 +269,12 @@ def find_external_network(name=None):
             params['name'] = name
         try:
             network = neutron.find_network(**params)
-        except tobiko.ObjectNotFound:
+        except tobiko.ObjectNotFound as ex:
             LOG.exception('No such network (%s):',
                           json.dumps(params, sort_keys=True))
             if name:
-                message = ('No such external network with name or ID '
-                           '{!r}').format(name)
-                raise ValueError(message)
+                raise ValueError("No such external network with name or ID "
+                                 f"'{name}'") from ex
 
     if network:
         LOG.debug('Found external network %r:\n%s',

tobiko/openstack/topology/_topology.py

@@ -15,7 +15,7 @@ from __future__ import absolute_import
 
 import collections
 import socket
-import typing
+import typing  # noqa
 import weakref
 
 
@@ -300,8 +300,9 @@ class OpenStackTopology(tobiko.SharedFixture):
     def get_group(self, group):
         try:
             return self._nodes_by_group[group]
-        except KeyError:
-            raise _exception.NoSuchOpenStackTopologyNodeGroup(group=group)
+        except KeyError as ex:
+            raise _exception.NoSuchOpenStackTopologyNodeGroup(
+                group=group) from ex
 
     def get_groups(self, groups):
         nodes = []

tobiko/podman/_shell.py

@@ -28,8 +28,10 @@ def discover_podman_socket(ssh_client=None, **execute_params):
         raise _exception.PodmanSocketNotFoundError(details=result.stderr)
     try:
         socket = result.stdout.splitlines()[0]
-    except IndexError:
-        raise _exception.PodmanSocketNotFoundError(details=result.stderr)
+    except IndexError as ex:
+        podman_error = _exception.PodmanSocketNotFoundError(
+            details=result.stderr)
+        raise podman_error from ex
     if '0 sockets listed' in socket:
         raise _exception.PodmanSocketNotFoundError(details=socket)
     return socket

tobiko/shell/sh/_process.py

@@ -223,9 +223,9 @@ class ShellProcessFixture(tobiko.SharedFixture):
         try:
             # Get attributes from parameters class
             return getattr(self.parameters, name)
-        except AttributeError:
+        except AttributeError as ex:
             message = "object {!r} has not attribute {!r}".format(self, name)
-            raise AttributeError(message)
+            raise AttributeError(message) from ex
 
     def kill(self):
         raise NotImplementedError

tobiko/shell/sh/_ssh.py

@@ -118,13 +118,13 @@ class SSHShellProcessFixture(_process.ShellProcessFixture):
                           exc_info=1)
             try:
                 attempt.check_limits()
-            except tobiko.RetryTimeLimitError:
+            except tobiko.RetryTimeLimitError as ex:
                 LOG.debug(f"Timed out creating remote process. ({details})")
                 raise _exception.ShellTimeoutExpired(command=command,
                                                      stdin=None,
                                                      stdout=None,
                                                      stderr=None,
-                                                     timeout=timeout)
+                                                     timeout=timeout) from ex
 
     def setup_stdin(self):
         self.stdin = _io.ShellStdin(