webkitpy: Small changes to merging script

third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/merge_results_unittest.py

 # Copyright 2017 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # pylint: disable=invalid-name
 # pylint complains about the assertXXX methods and the usage of short variables
 # m/a/b/d in the tests.
 
 import types
 import unittest
@@ skipping 253 matching lines @@
         mock_filesystem = MockFileSystem({'/s1/file1': 'a', '/s2/file1': 'b', '/s3/file1': 'c'}, dirs=['/output'])
 
         merger = merge_results.MergeFilesKeepFiles(mock_filesystem)
 
         with self.assertFilesAdded(mock_filesystem, {'/output/out_0': 'a', '/output/out_1': 'b', '/output/out_2': 'c'}):
             merger('/output/out', ['/s1/file1', '/s2/file1', '/s3/file1'])
 
 
 class DirMergerTests(FileSystemTestCase):
 
-    def test_failure_on_output_existing(self):
-        mock_filesystem = MockFileSystem({}, dirs=['/output'])
-        d = merge_results.DirMerger(mock_filesystem)
-        with self.assertRaises(OSError):
-            d.merge('/output', [])
-
-        self.assertDictEqual({}, mock_filesystem.files, "No new files should exist!")
-
     def test_success_no_overlapping_files(self):
         mock_filesystem = MockFileSystem({'/shard0/file1': '1', '/shard1/file2': '2'})
         d = merge_results.DirMerger(mock_filesystem)
         with self.assertFilesAdded(mock_filesystem, {'/output/file1': '1', '/output/file2': '2'}):
             d.merge('/output', ['/shard0', '/shard1'])
 
     def test_success_no_overlapping_files_but_matching_contents(self):
         mock_filesystem = MockFileSystem({'/shard0/file1': '1', '/shard1/file2': '1'})
         d = merge_results.DirMerger(mock_filesystem)
         with self.assertFilesAdded(mock_filesystem, {'/output/file1': '1', '/output/file2': '1'}):
@@ skipping 771 matching lines @@
 
     def test(self):
         fs = MockFileSystem(self.layout_test_filesystem)
 
         merger = merge_results.LayoutTestDirMerger(fs, results_json_value_overrides={'layout_tests_dir': 'src'})
         merger.merge('/out', ['/shards/0', '/shards/1'])
 
         for fname, contents in self.layout_test_output_filesystem.items():
             self.assertIn(fname, fs.files)
             self.assertMultiLineEqual(contents, fs.files[fname])