Use underscores to separate words in filenames in webkitpy.

third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/command_unittest.py

 # Copyright (c) 2016 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 11 matching lines @@
 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 import optparse
 import unittest
 
-from webkitpy.common.system.outputcapture import OutputCapture
+from webkitpy.common.system.output_capture import OutputCapture
 from webkitpy.tool.commands.command import Command
 
 
 class TrivialCommand(Command):
     name = "trivial"
     help_text = "help text"
     long_help = "trivial command long help text"
     show_in_main_help = True
 
     def __init__(self, **kwargs):
@@ skipping 29 matching lines @@
 
     def test_required_arguments(self):
         class TrivialCommandWithRequiredAndOptionalArgs(TrivialCommand):
             argument_names = "ARG1 ARG2 [ARG3]"
         two_required_arguments = TrivialCommandWithRequiredAndOptionalArgs()
         expected_logs = ("2 arguments required, 1 argument provided.  Provided: 'foo'  Required: ARG1 ARG2\n"
                          "See 'dummy-tool help trivial' for usage.\n")
         exit_code = OutputCapture().assert_outputs(self, two_required_arguments.check_arguments_and_execute,
                                                    [None, ["foo"], DummyTool()], expected_logs=expected_logs)
         self.assertEqual(exit_code, 1)