Clean the machine before running commands in the mini_installer test framework.

chrome/test/mini_installer/test_installer.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.
 
 """This script tests the installer with test cases specified in the config file.
 
 For each test case, it checks that the machine states after the execution of
 each command match the expected machine states. For more details, take a look at
 the design documentation at http://goo.gl/Q0rGM6
 """
@@ skipping 34 matching lines @@
     Args:
       test: An array of alternating state names and action names, starting and
           ending with state names.
       config: The Config object.
       path_resolver: A PathResolver object.
     """
     super(InstallerTest, self).__init__()
     self._test = test
     self._config = config
     self._path_resolver = path_resolver
+    self._was_successful = False
 
   def __str__(self):
     """Returns a string representing the test case.
 
     Returns:
       A string created by joining state names and action names together with
       ' -> ', for example, 'Test: clean -> install chrome -> chrome_installed'.
     """
     return 'Test: %s' % (' -> '.join(self._test))
 
   def runTest(self):
     """Run the test case."""
     # |test| is an array of alternating state names and action names, starting
     # and ending with state names. Therefore, its length must be odd.
     self.assertEqual(1, len(self._test) % 2,
                      'The length of test array must be odd')
 
-    # TODO(sukolsak): run a reset command that puts the machine in clean state.
-
     state = self._test[0]
     self._VerifyState(state)
 
     # Starting at index 1, we loop through pairs of (action, state).
     for i in range(1, len(self._test), 2):
       action = self._test[i]
-      self._RunCommand(self._config.actions[action])
+      RunCommand(self._config.actions[action], self._path_resolver)
 
       state = self._test[i + 1]
       self._VerifyState(state)
 
+    self._was_successful = True

[gab, 2013/09/16 18:33:45]

Add a comment stating why the test is successful if it made it here (i.e.,
RunCommand throws an exception on failure?).

[sukolsak, 2013/09/16 22:02:02]

Done.

+
+  def tearDown(self):
+    """Cleans up the machine if the test case fails or raises an exception."""

[gab, 2013/09/16 18:33:45]

Isn't "fail" and "raised an exception" the same thing? I'd cut this comment
after "fails."

[sukolsak, 2013/09/16 22:02:02]

Done. Python unittest makes a distinction between failures and errors. It counts
a test as failure if the test raises an AssertionError and as error if it raises
any other exceptions. But this also makes sense if we regard anything that is
not successful as failure.

+    if not self._was_successful:

[gab, 2013/09/16 18:41:22]

Rename |_was_successful| to something like |clean_on_teardown| since that's its
only purpose (and I think it's better that it not be interpreted too generally).

[sukolsak, 2013/09/16 22:02:02]

Done.

+      RunCleanCommand(True, self._path_resolver)
+
   def shortDescription(self):
     """Overridden from unittest.TestCase.
 
     We return None as the short description to suppress its printing.
     The default implementation of this method returns the docstring of the
     runTest method, which is not useful since it's the same for every test case.
     The description from the __str__ method is informative enough.
     """
     return None
 
   def _VerifyState(self, state):
     """Verifies that the current machine state matches a given state.
 
     Args:
       state: A state name.
     """
     try:
       verifier.Verify(self._config.states[state], self._path_resolver)
     except AssertionError as e:
       # If an AssertionError occurs, we intercept it and add the state name
       # to the error message so that we know where the test fails.
       raise AssertionError("In state '%s', %s" % (state, e))
 
-  def _RunCommand(self, command):
-    """Runs the given command from the current file's directory.
 
-    Args:
-      command: A command to run. It is expanded using ResolvePath.
-    """
-    resolved_command = self._path_resolver.ResolvePath(command)
-    script_dir = os.path.dirname(os.path.abspath(__file__))
-    exit_status = subprocess.call(resolved_command, shell=True, cwd=script_dir)
-    if exit_status != 0:
-      self.fail('Command %s returned non-zero exit status %s' % (
-          resolved_command, exit_status))
+def RunCommand(command, path_resolver):
+  """Runs the given command from the current file's directory.
+
+  This function throws an Exception if the command returns with non-zero exit
+  status.
+
+  Args:
+    command: A command to run. It is expanded using ResolvePath.
+    path_resolver: A PathResolver object.
+  """
+  resolved_command = path_resolver.ResolvePath(command)
+  script_dir = os.path.dirname(os.path.abspath(__file__))
+  exit_status = subprocess.call(resolved_command, shell=True, cwd=script_dir)
+  if exit_status != 0:
+    raise Exception('Command %s returned non-zero exit status %s' % (

[gab, 2013/09/16 18:41:22]

Why go from self.fail to throwing an exception?

Maybe we already talked about this, but I don't see a hint in the CL description
to why this was changed.

[sukolsak, 2013/09/16 22:02:02]

Because RunCommand is now a global function. I changed it so that
RunCleanCommand could be called outside the InstallerTest class. What self.fail
does is actually just throwing an Exception.

[gab, 2013/09/16 22:15:50]

Ah I see, man python is so subtle for that, unindent by 2 spaces and all of a
sudden you have a global function...! Sorry I hadn't noticed that.

+        command, exit_status))
+
+
+def RunCleanCommand(force_clean, path_resolver):
+  """Puts the machine in the clean state (i.e. Chrome not installed).
+
+  Args:
+    force_clean: A boolean indicating whether to force cleaning existing
+        installations.
+    path_resolver: A PathResolver object.
+  """
+  # TODO(sukolsak): Read the clean state from the config file and clean
+  # the machine according to it.
+  # TODO(sukolsak): Handle Chrome SxS installs.
+  commands = []
+  interactive_option = '--interactive' if not force_clean else ''
+  for level_option in ['', '--system-level']:
+    commands.append('python uninstall_chrome.py '
+                    '--chrome-long-name="$CHROME_LONG_NAME" '
+                    '--no-error-if-absent %s %s' %
+                    (level_option, interactive_option))
+  RunCommand(' && '.join(commands), path_resolver)
 
 
 def MergePropertyDictionaries(current_property, new_property):
   """Merges the new property dictionary into the current property dictionary.
 
   This is different from general dictionary merging in that, in case there are
   keys with the same name, we merge values together in the first level, and we
   override earlier values in the second level. For more details, take a look at
   http://goo.gl/uE0RoR
 
@@ skipping 48 matching lines @@
   config = Config()
   config.tests = config_data['tests']
   for state_name, state_property_filenames in config_data['states']:
     config.states[state_name] = ParsePropertyFiles(directory,
                                                    state_property_filenames)
   for action_name, action_command in config_data['actions']:
     config.actions[action_name] = action_command
   return config
 
 
-def RunTests(mini_installer_path, config):
+def RunTests(mini_installer_path, config, force_clean):
   """Tests the installer using the given Config object.
 
   Args:
     mini_installer_path: The path to mini_installer.exe.
     config: A Config object.
+    force_clean: A boolean indicating whether to force cleaning existing
+        installations.
 
   Returns:
     True if all the tests passed, or False otherwise.
   """
   suite = unittest.TestSuite()
   path_resolver = PathResolver(mini_installer_path)
+  RunCleanCommand(force_clean, path_resolver)
   for test in config.tests:
     suite.addTest(InstallerTest(test, config, path_resolver))
   result = unittest.TextTestRunner(verbosity=2).run(suite)
   return result.wasSuccessful()
 
 
 def main():
   usage = 'usage: %prog [options] config_filename'
   parser = optparse.OptionParser(usage, description='Test the installer.')
   parser.add_option('--build-dir', default='out',
                     help='Path to main build directory (the parent of the '
                          'Release or Debug directory)')
   parser.add_option('--target', default='Release',
                     help='Build target (Release or Debug)')
+  parser.add_option('--force-clean', action='store_true', dest='force_clean',
+                    default=False, help='Force cleaning existing installations')
   options, args = parser.parse_args()
   if len(args) != 1:
     parser.error('Incorrect number of arguments.')
   config_filename = args[0]
 
   mini_installer_path = os.path.join(options.build_dir, options.target,
                                      'mini_installer.exe')
   assert os.path.exists(mini_installer_path), ('Could not find file %s' %
                                                mini_installer_path)
   config = ParseConfigFile(config_filename)
-  if not RunTests(mini_installer_path, config):
+  if not RunTests(mini_installer_path, config, options.force_clean):
     return 1
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())