Makes the code simpler by automatically deducing the root directory to use.

tools/isolate/isolate_test.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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 json
+import os
+import tempfile
 import unittest
 
 import isolate
 
+ROOT_DIR = os.path.dirname(os.path.abspath(__file__))
+
 
 class Isolate(unittest.TestCase):
+  def setUp(self):
+    # Everything should work even from another directory.
+    os.chdir(os.path.dirname(ROOT_DIR))
+
+  def _run_process_options(self, values, variables, more_expected_data):
+    """Runs isolate.process_options() and verify the results."""
+    fd, temp_path = tempfile.mkstemp()
+    try:
+      # Reuse the file descriptor. On windows, it needs to be closed before
+      # process_options() opens it, because mkstemp() opens it without file
+      # sharing enabled.
+      with os.fdopen(fd, 'w') as f:
+        json.dump(values, f)
+      root_dir, infiles, data = isolate.process_options(
+          variables,
+          temp_path,
+          os.path.join('isolate', 'data', 'isolate', 'touch_root.isolate'),
+          self.fail)
+    finally:
+      os.remove(temp_path)
+
+    expected_data = {
+      u'command': ['python', 'touch_root.py'],
+      u'read_only': None,
+      u'relative_cwd': 'data/isolate',
+      u'resultfile': temp_path,
+      u'resultdir': tempfile.gettempdir(),
+      u'variables': {},
+    }
+    expected_data.update(more_expected_data)
+    expected_files = sorted(
+        ('isolate.py', os.path.join('data', 'isolate', 'touch_root.py')))
+    self.assertEquals(ROOT_DIR, root_dir)
+    self.assertEquals(expected_files, sorted(infiles))
+    self.assertEquals(expected_data, data)
+
   def test_load_empty(self):
     content = "{}"
     variables = {}
     command, infiles, read_only = isolate.load_isolate(
         content, variables, self.fail)
     self.assertEquals([], command)
     self.assertEquals([], infiles)
     self.assertEquals(None, read_only)
 
+  def test_process_options_empty(self):
+    # Passing nothing generates nothing unexpected.
+    self._run_process_options({}, [], {})
+
+  def test_process_options(self):
+    # The previous unexpected variables are kept, the 'variables' dictionary is
+    # updated.
+    values = {
+      'command': 'maybe',
+      'foo': 'bar',
+      'read_only': 2,
+      'relative_cwd': None,
+      'resultdir': '2',
+      'resultfile': [],
+      'variables': {
+        'unexpected': 'seriously',
+      },
+    }
+
+    expected_data = {
+      u'foo': u'bar',
+      u'variables': {
+        'expected': 'very',
+        u'unexpected': u'seriously',
+      },
+    }
+    self._run_process_options(values, ['expected=very'], expected_data)
+
 
 if __name__ == '__main__':
   unittest.main()