Extract functions from path recipe module so that step can depend on it

scripts/slave/recipe_modules/file/example.py

 # Copyright 2014 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.
 
 from infra.libs.infra_types import freeze
 
 DEPS = [
   'file',
   'path',
   'raw_io',
+  'step',
 ]
 
 
 TEST_CONTENTS = freeze({
   'simple': 'abcde',
   'spaces': 'abcde fgh',
   'symbols': '! ~&&',
   'multiline': '''ab
 cd
 efg
 ''',
 })
 
 
 def GenSteps(api):
+  # listdir demo.
+  result = api.file.listdir('fake dir', '/fake/dir')
+  for element in result:
+    api.step('manipulate %s' % str(element), ['some', 'command'])
+
+  # mkdtemp demo.
+  for prefix in ('prefix_a', 'prefix_b'):
+    # Create temp dir.
+    temp_dir = api.path.mkdtemp(prefix)
+    assert api.path.exists(temp_dir)
+    # Make |temp_dir| surface in expectation files.
+    api.step('print %s' % prefix, ['echo', temp_dir])
+
+  # rmwildcard demo
+  api.file.rmwildcard('*.o', api.path['slave_build'])
+
   for name, content in TEST_CONTENTS.iteritems():
     api.file.write('write_%s' % name, 'tmp_file.txt', content)
     actual_content = api.file.read(
         'read_%s' % name, 'tmp_file.txt',
         test_data=content
     )
     msg = 'expected %s but got %s' % (content, actual_content)
     assert actual_content == content, msg
 
   try:
     # copytree
     content = 'some file content'
     tmp_dir = api.path['slave_build'].join('copytree_example_tmp')
-    api.path.makedirs('makedirs', tmp_dir)
+    api.file.makedirs('makedirs', tmp_dir)
     path = tmp_dir.join('dummy_file')
     api.file.write('write %s' % path, path, content)
     new_tmp = api.path['slave_build'].join('copytree_example_tmp2')
     new_path = new_tmp.join('dummy_file')
     api.file.copytree('copytree', tmp_dir, new_tmp)
     actual_content = api.file.read('read %s' % new_path, new_path,
                                    test_data=content)
     assert actual_content == content
 
     # glob.
     files = api.file.glob(
         'glob', tmp_dir.join('*'),
         test_data=[tmp_dir.join('dummy_file')])
     assert files == [str(tmp_dir.join('dummy_file'))], files
 
   finally:
-    api.path.rmtree('cleanup', tmp_dir)
-    api.path.rmtree('cleanup2', new_tmp)
+    api.file.rmtree('cleanup', tmp_dir)
+    api.file.rmtree('cleanup2', new_tmp)
 
 
 def GenTests(api):
   yield api.test('file_io')