tox: bump the pylint version to 2.6.0 in the default run (#544)

Changes:

tox: bump the pylint version to 2.6.0 in the default run
Fix pylint 2.6.0 W0707 warnings (raise-missing-from)

7 files changed, 42 insertions, 25 deletions

diff --git a/tests/cloud_tests/platforms/azurecloud/instance.py b/tests/cloud_tests/platforms/azurecloud/instance.py
index a136cf0d..eedbaae8 100644
--- a/tests/cloud_tests/platforms/azurecloud/instance.py
+++ b/tests/cloud_tests/platforms/azurecloud/instance.py
@@ -134,9 +134,10 @@ class AzureCloudInstance(Instance):
                                  self.vm_name, vm_params)
             LOG.debug('creating instance %s from image_id=%s', self.vm_name,
                       self.image_id)
-        except CloudError:
-            raise RuntimeError('failed creating instance:\n{}'.format(
-                traceback.format_exc()))
+        except CloudError as e:
+            raise RuntimeError(
+                'failed creating instance:\n{}'.format(traceback.format_exc())
+            ) from e
 
         if wait:
             self.instance.wait()
diff --git a/tests/cloud_tests/platforms/azurecloud/platform.py b/tests/cloud_tests/platforms/azurecloud/platform.py
index cb62a74b..a664f612 100644
--- a/tests/cloud_tests/platforms/azurecloud/platform.py
+++ b/tests/cloud_tests/platforms/azurecloud/platform.py
@@ -59,9 +59,12 @@ class AzureCloudPlatform(Platform):
             self.vnet = self._create_vnet()
             self.subnet = self._create_subnet()
             self.nic = self._create_nic()
-        except CloudError:
-            raise RuntimeError('failed creating a resource:\n{}'.format(
-                traceback.format_exc()))
+        except CloudError as e:
+            raise RuntimeError(
+                'failed creating a resource:\n{}'.format(
+                    traceback.format_exc()
+                )
+            ) from e
 
     def create_instance(self, properties, config, features,
                         image_id, user_data=None):
@@ -105,8 +108,10 @@ class AzureCloudPlatform(Platform):
             if image_id.find('__') > 0:
                 image_id = image_id.split('__')[1]
                 LOG.debug('image_id shortened to %s', image_id)
-        except KeyError:
-            raise RuntimeError('no images found for %s' % img_conf['release'])
+        except KeyError as e:
+            raise RuntimeError(
+                'no images found for %s' % img_conf['release']
+            ) from e
 
         return AzureCloudImage(self, img_conf, image_id)
 
@@ -140,9 +145,11 @@ class AzureCloudPlatform(Platform):
                 secret=azure_creds['clientSecret'],
                 tenant=azure_creds['tenantId'])
             return credentials, subscription_id
-        except KeyError:
-            raise RuntimeError('Please configure Azure service principal'
-                               ' credentials in %s' % cred_file)
+        except KeyError as e:
+            raise RuntimeError(
+                'Please configure Azure service principal'
+                ' credentials in %s' % cred_file
+            ) from e
 
     def _create_resource_group(self):
         """Create resource group"""
diff --git a/tests/cloud_tests/platforms/ec2/instance.py b/tests/cloud_tests/platforms/ec2/instance.py
index ab6037b1..d2e84047 100644
--- a/tests/cloud_tests/platforms/ec2/instance.py
+++ b/tests/cloud_tests/platforms/ec2/instance.py
@@ -49,11 +49,11 @@ class EC2Instance(Instance):
             # OutputBytes comes from platform._decode_console_output_as_bytes
             response = self.instance.console_output()
             return response['OutputBytes']
-        except KeyError:
+        except KeyError as e:
             if 'Output' in response:
                 msg = ("'OutputBytes' did not exist in console_output() but "
                        "'Output' did: %s..." % response['Output'][0:128])
-                raise util.PlatformError('console_log', msg)
+                raise util.PlatformError('console_log', msg) from e
             return ('No Console Output [%s]' % self.instance).encode()
 
     def destroy(self):
diff --git a/tests/cloud_tests/platforms/ec2/platform.py b/tests/cloud_tests/platforms/ec2/platform.py
index 7a3d0fe0..b61a2ffb 100644
--- a/tests/cloud_tests/platforms/ec2/platform.py
+++ b/tests/cloud_tests/platforms/ec2/platform.py
@@ -35,12 +35,14 @@ class EC2Platform(Platform):
             self.ec2_resource = b3session.resource('ec2')
             self.ec2_region = b3session.region_name
             self.key_name = self._upload_public_key(config)
-        except botocore.exceptions.NoRegionError:
+        except botocore.exceptions.NoRegionError as e:
             raise RuntimeError(
-                'Please configure default region in $HOME/.aws/config')
-        except botocore.exceptions.NoCredentialsError:
+                'Please configure default region in $HOME/.aws/config'
+            ) from e
+        except botocore.exceptions.NoCredentialsError as e:
             raise RuntimeError(
-                'Please configure ec2 credentials in $HOME/.aws/credentials')
+                'Please configure ec2 credentials in $HOME/.aws/credentials'
+            ) from e
 
         self.vpc = self._create_vpc()
         self.internet_gateway = self._create_internet_gateway()
@@ -125,8 +127,10 @@ class EC2Platform(Platform):
 
         try:
             image_ami = image['id']
-        except KeyError:
-            raise RuntimeError('No images found for %s!' % img_conf['release'])
+        except KeyError as e:
+            raise RuntimeError(
+                'No images found for %s!' % img_conf['release']
+            ) from e
 
         LOG.debug('found image: %s', image_ami)
         image = EC2Image(self, img_conf, image_ami)
@@ -195,7 +199,7 @@ class EC2Platform(Platform):
                 CidrBlock=self.ipv4_cidr,
                 AmazonProvidedIpv6CidrBlock=True)
         except botocore.exceptions.ClientError as e:
-            raise RuntimeError(e)
+            raise RuntimeError(e) from e
 
         vpc.wait_until_available()
         self._tag_resource(vpc)
diff --git a/tests/cloud_tests/platforms/lxd/instance.py b/tests/cloud_tests/platforms/lxd/instance.py
index b27b9848..2b973a08 100644
--- a/tests/cloud_tests/platforms/lxd/instance.py
+++ b/tests/cloud_tests/platforms/lxd/instance.py
@@ -175,7 +175,8 @@ class LXDInstance(Instance):
             raise PlatformError(
                 "console log",
                 "Console log failed [%d]: stdout=%s stderr=%s" % (
-                    e.exit_code, e.stdout, e.stderr))
+                    e.exit_code, e.stdout, e.stderr)
+            ) from e
 
     def reboot(self, wait=True):
         """Reboot instance."""
diff --git a/tests/cloud_tests/platforms/platforms.py b/tests/cloud_tests/platforms/platforms.py
index 58f65e52..ac3b6563 100644
--- a/tests/cloud_tests/platforms/platforms.py
+++ b/tests/cloud_tests/platforms/platforms.py
@@ -74,8 +74,10 @@ class Platform(object):
 
         try:
             return tmirror.json_entries[0]
-        except IndexError:
-            raise RuntimeError('no images found with filter: %s' % img_filter)
+        except IndexError as e:
+            raise RuntimeError(
+                'no images found with filter: %s' % img_filter
+            ) from e
 
 
 class FilterMirror(mirrors.BasicMirrorWriter):
diff --git a/tests/cloud_tests/testcases/__init__.py b/tests/cloud_tests/testcases/__init__.py
index e8c371ca..bb9785d3 100644
--- a/tests/cloud_tests/testcases/__init__.py
+++ b/tests/cloud_tests/testcases/__init__.py
@@ -21,8 +21,10 @@ def discover_test(test_name):
         config.name_sanitize(test_name))
     try:
         testmod = importlib.import_module(testmod_name)
-    except NameError:
-        raise ValueError('no test verifier found at: {}'.format(testmod_name))
+    except NameError as e:
+        raise ValueError(
+            'no test verifier found at: {}'.format(testmod_name)
+        ) from e
 
     found = [mod for name, mod in inspect.getmembers(testmod)
              if (inspect.isclass(mod)