test: Fix all pylint issues in utils.py, tabletmanager.py and update_stream.py.

test/tabletmanager.py

@@ -270,9 +270,11 @@ class TestTabletManager(unittest.TestCase):
     tablet_62344.kill_vttablet()
 
   def test_restart(self):
-    """test_restart tests that when starting a second vttablet with the same
-    configuration as another one, it will kill the previous process
-    and take over listening on the socket.
+    """Test restart behavior of vttablet.
+
+    Tests that when starting a second vttablet with the same configuration as
+    another one, it will kill the previous process and take over listening on
+    the socket.
 
     If vttablet listens to other ports (like gRPC), this feature will
     break. We believe it is not widely used, so we're OK with this for now.
@@ -518,6 +520,7 @@ class TestTabletManager(unittest.TestCase):
 
   def test_no_mysql_healthcheck(self):
     """This test starts a vttablet with no mysql port, while mysql is down.
+
     It makes sure vttablet will start properly and be unhealthy.
     Then we start mysql, and make sure vttablet becomes healthy.
     """

test/update_stream.py

@@ -1,10 +1,5 @@
 #!/usr/bin/env python
 
-import warnings
-# Dropping a table inexplicably produces a warning despite
-# the "IF EXISTS" clause. Squelch these warnings.
-warnings.simplefilter('ignore')
-
 import logging
 import traceback
 import threading
@@ -170,7 +165,7 @@ class TestUpdateStream(unittest.TestCase):
     try:
       for _ in replica_conn.stream_update(start_position):
         break
-    except Exception as e:
+    except dbexceptions.DatabaseError as e:
       self.assertIn('update stream service is not enabled', str(e))
     replica_conn.close()
 
@@ -202,7 +197,7 @@ class TestUpdateStream(unittest.TestCase):
         if stream_event.category == update_stream.StreamEvent.DML:
           logging.debug('Test Service Enabled: Pass')
           break
-    except Exception as e:
+    except dbexceptions.DatabaseError as e:
       self.fail('Exception in getting stream from replica: %s\n Traceback %s' %
                 (str(e), traceback.format_exc()))
     thd.join(timeout=30)
@@ -254,10 +249,11 @@ class TestUpdateStream(unittest.TestCase):
     return
 
   def test_stream_parity(self):
-    """test_stream_parity checks the parity of streams received
-    from master and replica for the same writes. Also tests
-    transactions are retrieved properly.
+    """Tests parity of streams between master and replica for the same writes.
+
+    Also tests transactions are retrieved properly.
     """
+
     global master_start_position
 
     timeout = 30

test/utils.py

@@ -9,7 +9,7 @@ import shlex
 import shutil
 import signal
 import socket
-from subprocess import Popen, CalledProcessError, PIPE
+import subprocess
 import sys
 import time
 import unittest
@@ -244,12 +244,12 @@ def run(cmd, trap_output=False, raise_on_error=True, **kargs):
   else:
     args = cmd
   if trap_output:
-    kargs['stdout'] = PIPE
-    kargs['stderr'] = PIPE
+    kargs['stdout'] = subprocess.PIPE
+    kargs['stderr'] = subprocess.PIPE
   logging.debug(
       'run: %s %s', str(cmd),
       ', '.join('%s=%s' % x for x in kargs.iteritems()))
-  proc = Popen(args, **kargs)
+  proc = subprocess.Popen(args, **kargs)
   proc.args = args
   stdout, stderr = proc.communicate()
   if proc.returncode:
@@ -268,13 +268,13 @@ def run_fail(cmd, **kargs):
     args = shlex.split(cmd)
   else:
     args = cmd
-  kargs['stdout'] = PIPE
-  kargs['stderr'] = PIPE
+  kargs['stdout'] = subprocess.PIPE
+  kargs['stderr'] = subprocess.PIPE
   if options.verbose == 2:
     logging.debug(
         'run: (expect fail) %s %s', cmd,
         ', '.join('%s=%s' % x for x in kargs.iteritems()))
-  proc = Popen(args, **kargs)
+  proc = subprocess.Popen(args, **kargs)
   proc.args = args
   stdout, stderr = proc.communicate()
   if proc.returncode == 0:
@@ -297,7 +297,7 @@ def run_bg(cmd, **kargs):
     args = shlex.split(cmd)
   else:
     args = cmd
-  proc = Popen(args=args, **kargs)
+  proc = subprocess.Popen(args=args, **kargs)
   proc.args = args
   _add_proc(proc)
   return proc
@@ -315,7 +315,8 @@ def wait_procs(proc_list, raise_on_error=True):
       if options.verbose >= 1 and proc.returncode not in (-9,):
         sys.stderr.write('proc failed: %s %s\n' % (proc.returncode, proc.args))
       if raise_on_error:
-        raise CalledProcessError(proc.returncode, ' '.join(proc.args))
+        raise subprocess.CalledProcessError(proc.returncode,
+                                            ' '.join(proc.args))
 
 
 def validate_topology(ping_tablets=False):
@@ -359,16 +360,13 @@ def wait_step(msg, timeout, sleep_time=1.0):
 
 # vars helpers
 def get_vars(port):
-  """Returns the dict for vars from a vtxxx process.
-
-  Returns: None if we can't get them.
-  """
+  """Returns the dict for vars from a vtxxx process. None if not available."""
   try:
     url = 'http://localhost:%d/debug/vars' % int(port)
     f = urllib2.urlopen(url)
     data = f.read()
     f.close()
-  except:
+  except urllib2.URLError:
     return None
   try:
     return json.loads(data)
@@ -470,8 +468,13 @@ def wait_for_tablet_type(tablet_alias, expected_type, timeout=10):
 def wait_for_replication_pos(tablet_a, tablet_b, timeout=60.0):
   """Waits for tablet B to catch up to the replication position of tablet A.
 
-  If the replication position does not catch up within timeout seconds, it will
-  raise a TestError.
+  Args:
+    tablet_a: tablet Object for tablet A.
+    tablet_b: tablet Object for tablet B.
+    timeout: Timeout in seconds.
+
+  Raises:
+    TestError: replication position did not catch up within timeout seconds.
   """
   replication_pos_a = mysql_flavor().master_position(tablet_a)
   while True:
@@ -494,8 +497,7 @@ class VtGate(object):
   """VtGate object represents a vtgate process."""
 
   def __init__(self, port=None):
-    """Creates the Vtgate instance and reserve the ports if necessary.
-    """
+    """Creates the Vtgate instance and reserve the ports if necessary."""
     self.port = port or environment.reserve_ports(1)
     if protocols_flavor().vtgate_protocol() == 'grpc':
       self.grpc_port = environment.reserve_ports(1)
@@ -506,11 +508,8 @@ class VtGate(object):
             topo_impl=None, cache_ttl='1s',
             timeout_total='4s', timeout_per_conn='2s',
             extra_args=None):
-    """Starts the process for this vtgate instance.
+    """Start vtgate. Saves it into the global vtgate variable if not set yet."""
 
-    If no other instance has been started, saves it into the global
-    vtgate variable.
-    """
     args = environment.binary_args('vtgate') + [
         '-port', str(self.port),
         '-cell', cell,
@@ -725,13 +724,7 @@ def run_vtworker(clargs, auto_log=False, expect_fail=False, **kwargs):
 
 
 def run_vtworker_bg(clargs, auto_log=False, **kwargs):
-  """Starts a background vtworker process.
-
-  Returns:
-    proc - process returned by subprocess.Popen
-    port - int with the port number that the vtworker is running with
-    rpc_port - int with the port number of the RPC interface
-  """
+  """Starts a background vtworker process."""
   cmd, port, rpc_port = _get_vtworker_cmd(clargs, auto_log)
   return run_bg(cmd, **kwargs), port, rpc_port
 
@@ -739,6 +732,10 @@ def run_vtworker_bg(clargs, auto_log=False, **kwargs):
 def _get_vtworker_cmd(clargs, auto_log=False):
   """Assembles the command that is needed to run a vtworker.
 
+  Args:
+    clargs: Command line arguments passed to vtworker.
+    auto_log: If true, set --stderrthreshold according to the test log level.
+
   Returns:
     cmd - list of cmd arguments, can be passed to any `run`-like functions
     port - int with the port number that the vtworker is running with
@@ -950,14 +947,7 @@ def check_shard_query_services(
 
 def check_tablet_query_service(
     testcase, tablet, serving, tablet_control_disabled):
-  """Check that the query service is enabled or disabled on the tablet.
-
-  It will also check if the tablet control status is the reason for
-  being enabled / disabled.
-
-  It will also run a remote RunHealthCheck to be sure it doesn't change
-  the serving state.
-  """
+  """Check that the query service is enabled or disabled on the tablet."""
   tablet_vars = get_vars(tablet.port)
   if serving:
     expected_state = 'SERVING'
@@ -977,6 +967,7 @@ def check_tablet_query_service(
     testcase.assertNotIn('Query Service disabled by TabletControl', status)
 
   if tablet.tablet_type == 'rdonly':
+    # Run RunHealthCheck to be sure the tablet doesn't change its serving state.
     run_vtctl(['RunHealthCheck', tablet.tablet_alias, 'rdonly'],
               auto_log=True)
 
@@ -1116,7 +1107,7 @@ class Vtctld(object):
     if protocol == 'grpc':
       # import the grpc vtctl client implementation, change the port
       if python:
-        from vtctl import grpc_vtctl_client
+        from vtctl import grpc_vtctl_client  # pylint: disable=g-import-not-at-top,unused-variable
       rpc_port = self.grpc_port
     return (protocol, '%s:%d' % (socket.getfqdn(), rpc_port))
 
@@ -1155,6 +1146,9 @@ def uint64_to_hex(integer):
   Args:
     integer: the value to print.
 
+  Returns:
+    String with the hex representation.
+
   Raises:
     ValueError: if the integer is out of range.
   """