Add PRESUBMIT tests for _CheckUserActionUpdate function.

Presubmit does not contain any tests for the _CheckUserActionUpdate
function. This commit adds a test to check against an action in
actions.xml and one that is not found there. To do this we have to
improve the MockInputApi and MockFile classes.

BUG=462814

Review URL: https://codereview.chromium.org/966703003

Cr-Commit-Position: refs/heads/master@{#318759}

PRESUBMIT_test.py

@@ -775,5 +775,39 @@ class TryServerMasterTest(unittest.TestCase):
             bot, master, PRESUBMIT.GetTryServerMasterForBot(bot)))
 
 
+class UserMetricsActionTest(unittest.TestCase):
+  def testUserMetricsActionInActions(self):
+    input_api = MockInputApi()
+    file_with_user_action = 'file_with_user_action.cc'
+    contents_with_user_action = [
+      'base::UserMetricsAction("AboutChrome")'
+    ]
+
+    input_api.files = [MockFile(file_with_user_action,
+                                contents_with_user_action)]
+
+    self.assertEqual(
+      [], PRESUBMIT._CheckUserActionUpdate(input_api, MockOutputApi()))
+
+
+  def testUserMetricsActionNotAddedToActions(self):
+    input_api = MockInputApi()
+    file_with_user_action = 'file_with_user_action.cc'
+    contents_with_user_action = [
+      'base::UserMetricsAction("NotInActionsXml")'
+    ]
+
+    input_api.files = [MockFile(file_with_user_action,
+                                contents_with_user_action)]
+
+    output = PRESUBMIT._CheckUserActionUpdate(input_api, MockOutputApi())
+    self.assertEqual(
+      ('File %s line %d: %s is missing in '
+       'tools/metrics/actions/actions.xml. Please run '
+       'tools/metrics/actions/extract_actions.py to update.'
+       % (file_with_user_action, 1, 'NotInActionsXml')),
+      output[0].message)
+
+
 if __name__ == '__main__':
   unittest.main()

PRESUBMIT_test_mocks.py

@@ -32,6 +32,9 @@ class MockInputApi(object):
   def AffectedSourceFiles(self, file_filter=None):
     return self.files
 
+  def LocalPaths(self):
+    return self.files
+
   def PresubmitLocalPath(self):
     return os.path.dirname(__file__)
 
@@ -62,22 +65,22 @@ class MockOutputApi(object):
       return self.message
 
   class PresubmitError(PresubmitResult):
-    def __init__(self, message, items, long_text=''):
+    def __init__(self, message, items=None, long_text=''):
       MockOutputApi.PresubmitResult.__init__(self, message, items, long_text)
       self.type = 'error'
 
   class PresubmitPromptWarning(PresubmitResult):
-    def __init__(self, message, items, long_text=''):
+    def __init__(self, message, items=None, long_text=''):
       MockOutputApi.PresubmitResult.__init__(self, message, items, long_text)
       self.type = 'warning'
 
   class PresubmitNotifyResult(PresubmitResult):
-    def __init__(self, message, items, long_text=''):
+    def __init__(self, message, items=None, long_text=''):
       MockOutputApi.PresubmitResult.__init__(self, message, items, long_text)
       self.type = 'notify'
 
   class PresubmitPromptOrNotify(PresubmitResult):
-    def __init__(self, message, items, long_text=''):
+    def __init__(self, message, items=None, long_text=''):
       MockOutputApi.PresubmitResult.__init__(self, message, items, long_text)
       self.type = 'promptOrNotify'
 
@@ -103,6 +106,14 @@ class MockFile(object):
   def LocalPath(self):
     return self._local_path
 
+  def rfind(self, p):
+    """os.path.basename is called on MockFile so we need an rfind method."""
+    return self._local_path.rfind(p)
+
+  def __getitem__(self, i):
+    """os.path.basename is called on MockFile so we need a get method."""
+    return self._local_path[i]
+
 
 class MockAffectedFile(MockFile):
   def AbsoluteLocalPath(self):