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

chrome/test/mini_installer/file_visitor.py

Index: chrome/test/mini_installer/file_visitor.py
diff --git a/chrome/test/mini_installer/file_visitor.py b/chrome/test/mini_installer/file_visitor.py
new file mode 100644
index 0000000000000000000000000000000000000000..0254a3bf8c673c676e8e83cf7ed5bf5cb0d2f9b3
--- /dev/null
+++ b/chrome/test/mini_installer/file_visitor.py
@@ -0,0 +1,64 @@
+# 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.
+
+import os
+import shutil
+
+import visitor
+
+class FileVisitor(visitor.Visitor):
+  """ Visitor for file entry in property
+  """
+  def _VisitEntry(self, entry_name, entry_value):
+    """ Check whether a file is existed or not.
+
+        Args:
+          'entry_name' - A string represents the path to the file being
+                         verified.
+          'entry_value' - A dictionary with the following key and value:
+                          'exists': a boolean indicating whether the file should
+                          exist.
+    """
+    file_path = self._variable_expander.Expand(entry_name)
+    is_file_exists = os.path.exists(file_path)
+    should_file_exist = entry_value['exists']
+    self._HandleFile(file_path, is_file_exists, should_file_exist)
+
+  def _HandleFile(self, file_path, is_file_exists, should_file_exist):
+    """ Abstract function to check a file."
+
+        Args:
+          file_path: A string represents the path of the file.
+          is_file_exists: A boolean represents whether the file existed.
+          should_file_exist: A boolean represents whether the file should exist.
+    """
+    raise NotImplementedError()
+
+
+class FileVerifier(FileVisitor):
+  """Verifies that the current files match the expectation dictionaries."""
+  def _HandleFile(self, file_path, is_file_exists, should_file_exist):
+    """ Overridden FileVisitor._HandleFile.
+
+        Throw AssertionError if |is_file_exists| doesn't match
+        |should_file_exist|.
+    """
+    error_message = ""
+    if is_file_exists:
+      error_message = 'File %s exists' % file_path
+    else:
+      error_message = 'File %s is missing' % file_path
+    assert should_file_exist == is_file_exists, error_message
+
+class FileCleaner(FileVisitor):
+  """ Reset the current file system state to match the expectation.
+  """
+  def _HandleFile(self, file_path, is_file_exists, should_file_exist):
+    """ Overridden FileVisitor._HandleFile.
+
+        Delete the file if file is existed but shouldn't exist. Only support
+        Directory.
+    """
+    if is_file_exists and not should_file_exist and os.path.isdir(file_path):
+      shutil.rmtree(file_path, ignore_errors=True)