Fix lint errors to enable stricter PyLint rules

webrtc/modules/audio_processing/test/py_quality_assessment/apm_quality_assessment_unittest.py

 # Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 """Unit tests for the apm_quality_assessment module.
 """
 
 import unittest
 
 import apm_quality_assessment
 
 class TestSimulationScript(unittest.TestCase):
   """Unit tests for the apm_quality_assessment module.
   """
 
-  def test_main(self):
+  def testMain(self):
     # Exit with error code if no arguments are passed.
     with self.assertRaises(SystemExit) as cm:
       apm_quality_assessment.main()
     self.assertGreater(cm.exception.code, 0)