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

scripts/slave/recipe_modules/git/example.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.
 
 DEPS = [
   'git',
   'path',
+  'platform',
 ]
 
 
 def GenSteps(api):
   url = 'https://chromium.googlesource.com/chromium/src.git'
 
   # You can use api.git.checkout to perform all the steps of a safe checkout.
   yield api.git.checkout(url, recursive=True)
 
   # If you need to run more arbitrary git commands, you can use api.git itself,
   # which behaves like api.step(), but automatically sets the name of the step.
   yield api.git('status', cwd=api.path.checkout())
 
 
-def GenTests(_api):
-  yield 'basic', {}
+def GenTests(api):
+  yield api.test('basic')
 
-  yield 'platform_win', {
-    'mock': {
-      'platform': {
-        'name': 'win'
-      }
-    }
-  }
+  yield api.test('platform_win') + api.platform.name('win')