Cleanup machine based on the state in configuration file for mini installer test.

chrome/test/mini_installer/file_verifier.py

 # Copyright 2013 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.
 
 import os
 
 import verifier
 
 
 class FileVerifier(verifier.Verifier):
   """Verifies that the current files match the expectation dictionaries."""
 
+  def __init__(self):
+    self._file_path = None
+    self._file_exists = None
+
   def _VerifyExpectation(self, expectation_name, expectation,
                          variable_expander):
     """Overridden from verifier.Verifier.
 
     This method will throw an AssertionError if file state doesn't match the
     |expectation|.
 
     Args:
       expectation_name: Path to the file being verified. It is expanded using
           Expand.
       expectation: A dictionary with the following key and value:
           'exists' a boolean indicating whether the file should exist.
       variable_expander: A VariableExpander object.
     """
-    file_path = variable_expander.Expand(expectation_name)
-    file_exists = os.path.exists(file_path)
-    assert expectation['exists'] == file_exists, \
-        ('File %s exists' % file_path) if file_exists else \
-        ('File %s is missing' % file_path)
+    self._file_path = variable_expander.Expand(expectation_name)

[grt (UTC plus 2), 2017/03/14 09:19:44]

why store state in the verifier? one instance is used repeatedly over many
inputs, so i don't see why this is necessary or beneficial.

+    self._file_exists = os.path.exists(self._file_path)
+    self._Assert(expectation['exists'] == self._file_exists,
+        ('File %s exists' % self._file_path) if self._file_exists \
+        else ('File %s is missing' % self._file_path))