Refactor the way that TestApi works so that it is actually useful.

scripts/slave/annotated_run.py

 #!/usr/bin/env python
 # Copyright (c) 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.
 
 """Entry point for fully-annotated builds.
 
 This script is part of the effort to move all builds to annotator-based
 systems. Any builder configured to use the AnnotatorFactory.BaseFactory()
 found in scripts/master/factory/annotator_factory.py executes a single
@@ skipping 364 matching lines @@
         if recipe_module:
           break
       else:
         s.step_text('recipe not found')
         s.step_failure()
         return MakeStepsRetval(2, None)
 
     properties = factory_properties.copy()
     properties.update(build_properties)
     stream.emit('Running recipe with %s' % (properties,))
-    steps = recipe_module.GenSteps(api(recipe_module.DEPS,
-                                       mod_dirs=MODULE_DIRS,
+    steps = recipe_module.GenSteps(api(MODULE_DIRS,
+                                       recipe_module.DEPS,
                                        properties=properties,
                                        step_history=step_history))
     assert inspect.isgenerator(steps)
 
   # Execute annotator.py with steps if specified.
   # annotator.py handles the seeding, execution, and annotation of each step.
   failed = False
 
   test_mode = test_data is not None
 
   for step in ensure_sequence_of_steps(steps):
     if failed and not step.get('always_run', False):
       step_result = StepData(step, None)
       step_history[step['name']] = step_result
       continue
 
-    test_data_item = test_data.pop(step['name'], {}) if test_mode else None
+    test_data_item = None
+    mock_fn = step.pop('mock_fn', None)
+    if test_mode:
+      test_data_item = mock_fn() if mock_fn else {}
+      test_data_item.update(test_data.pop(step['name'], {}))
+
     placeholders = render_step(step, test_data_item)
 
     assert step['name'] not in step_history, (
       'Step "%s" is already in step_history!' % step['name'])
 
     callback = step_callback(step, step_history, placeholders, test_data_item)
 
     if not test_mode:
       step_result = annotator.run_step(
         stream, followup_fn=callback, **step)
@@ skipping 37 matching lines @@
 
 def shell_main(argv):
   if UpdateScripts():
     return subprocess.call([sys.executable] + argv)
   else:
     return main(argv)
 
 
 if __name__ == '__main__':
   sys.exit(shell_main(sys.argv))