Remove git lockfile flakiness on win (bot_update)

tests/bot_update_coverage_test.py

Index: tests/bot_update_coverage_test.py
diff --git a/tests/bot_update_coverage_test.py b/tests/bot_update_coverage_test.py
index f055a9ba64b64c296420cf64bfa3ca39cbda4347..851c8523fc88df19725d66608059de7350279776 100755
--- a/tests/bot_update_coverage_test.py
+++ b/tests/bot_update_coverage_test.py
@@ -7,6 +7,7 @@ import codecs
 import copy
 import json
 import os
+import subprocess
 import sys
 import unittest
 
@@ -162,6 +163,15 @@ def fake_git(*args, **kwargs):
   return bot_update.call('git', *args, **kwargs)
 
 
+class MockSubprocess():
+  def __init__(self):
+    self.calls = []
+
+  def call(self, command):
+    self.calls.append(command)
+    return 0
+
+
 class BotUpdateUnittests(unittest.TestCase):
   def setUp(self):
     self.filesystem = FakeFilesystem()
@@ -180,11 +190,17 @@ class BotUpdateUnittests(unittest.TestCase):
     self.old_codecs_open = codecs.open
     setattr(codecs, 'open', self.filesystem.open)
 
+    self.subprocess = MockSubprocess()
+    self.old_sp_call = subprocess.call
+    setattr(subprocess, 'call', self.subprocess.call)
+
   def tearDown(self):
     setattr(bot_update, 'call', self.old_call)
     setattr(os, 'getcwd', self.old_os_cwd)
     delattr(bot_update, 'open')
     setattr(codecs, 'open', self.old_codecs_open)
+    delattr(subprocess, 'call')
+    setattr(subprocess, 'call', self.old_sp_call)
 
   def testBasic(self):
     bot_update.ensure_checkout(**self.params)
@@ -195,6 +211,16 @@ class BotUpdateUnittests(unittest.TestCase):
     bot_update.ensure_checkout(**self.params)
     return self.call.records
 
+  def testMaybeRemoveWinLockfile(self):
+    git_lockfile_err = '''
+        fatal: Unable to create 'E:/b/c/b/win/src/.git/index.lock': File exists.
+        '''
+    bot_update.maybe_remove_win_lockfile('win32', git_lockfile_err)
+    self.assertEqual(
+        self.subprocess.calls,
+        [['cmd.exe', '/c', 'del', '/f',
+          '/q', 'E:/b/c/b/win/src/.git/index.lock']])
+
 
 if __name__ == '__main__':
   unittest.main()