Fix various pylint violations

+ SchedUtils.py: Do not use `len(SEQUENCE)` to determine if a sequence is empty
+ VatHistory.py: Do not use `len(SEQUENCE)` to determine if a sequence is empty
+ VppCounters.py: Do not use `len(SEQUENCE)` to determine if a sequence is empty
+ Memif.py:
++ Do not use `len(SEQUENCE)` to determine if a sequence is empty
++ Either all return statements in a function should return an expression,
   or none of them should.
++ Update :return: on possible None.
+ Classify.py: Unnecessary "else" after "return"
+ ContainerUtils.py: Useless super delegation in method '__init__'
+ CpuUtils.py: Do not use `len(SEQUENCE)` to determine if a sequence is empty
+ DropRateSearch.py: Either all return statements in a function
  should return an expression, or none of them should.
+ IPv4NodeAddress.py: Do not use `len(SEQUENCE)` to determine if a sequence is empty
++ Also improve docstrings.
+ IPv4Setup.py: Useless super delegation in method '__init__'
+ IPv6Setup.py: Do not use `len(SEQUENCE)` to determine if a sequence is empty
++ Also improve docstrings.
+ IPv6Setup.py: standard import "from ipaddress import IPv6Network"
  should be placed before "from robot.api import logger"
+ MacSwap.py: Trailing newlines
+ NATUtil.py: Do not use `len(SEQUENCE)` to determine if a sequence is empty
+ NodePath.py: Unnecessary "else" after "return"
+ Tap.py: Do not use `len(SEQUENCE)` to determine if a sequence is empty
+ topology.py: Either all return statements in a function
  should return an expression, or none of them should.
+ topology.py: Unnecessary "else" after "return"
++ Do not use `len(SEQUENCE)` to determine if a sequence is empty
++ Improve docstrings
+ DUTSetup.py: Do not use `len(SEQUENCE)` to determine if a sequence is empty
++ Also do not compare int(ret_code) just to access zero-ness.
+ ssh.py: Do not use `len(SEQUENCE)` to determine if a sequence is empty
+ InterfaceUtil.py: Unnecessary "else" after "return"

Change-Id: Iba4244aa79661ee7df15fed5c7c6dbf04dfa88b2
Signed-off-by: Vratko Polak <vrpolak@cisco.com>

1 files changed, 4 insertions, 5 deletions

diff --git a/resources/libraries/python/VppCounters.py b/resources/libraries/python/VppCounters.py
index 5dc14a9a4e..b2c3b01c60 100644
--- a/resources/libraries/python/VppCounters.py
+++ b/resources/libraries/python/VppCounters.py
@@ -208,8 +208,7 @@ class VppCounters(object):
             vat.vat_terminal_exec_cmd('want_stats enable')
             for _ in range(0, 12):
                 stats_table = vat.vat_terminal_exec_cmd('dump_stats_table')
-                if_counters = stats_table['interface_counters']
-                if len(if_counters) > 0:
+                if stats_table['interface_counters']:
                     self._stats_table = stats_table
                     return stats_table
                 time.sleep(1)
@@ -259,15 +258,15 @@ class VppCounters(object):
             return 0
 
         if_counters = self._stats_table.get('interface_counters')
-        if if_counters is None or len(if_counters) == 0:
+        if not if_counters:
             logger.trace('No interface counters.')
             return 0
         for counter in if_counters:
             if counter['vnet_counter_type'] == version:
                 data = counter['data']
                 return data[if_index]
-        logger.trace('{i} {v} counter not found.'.format(i=interface,
-                                                         v=version))
+        logger.trace('{i} {v} counter not found.'.format(
+            i=interface, v=version))
         return 0
 
     @staticmethod