[loader] Make recipe engine support examples/ module subdir

recipe_modules/shutil/example.py

-# Copyright 2016 The LUCI Authors. All rights reserved.
-# Use of this source code is governed under the Apache License, Version 2.0
-# that can be found in the LICENSE file.
-
-from recipe_engine.types import freeze
-
-
-DEPS = [
-  'path',
-  'shutil',
-  'step',
-]
-
-TEST_CONTENTS = freeze({
-  'simple': 'abcde',
-  'spaces': 'abcde fgh',
-  'symbols': '! ~&&',
-  'multiline': '''ab
-cd
-efg
-''',
-})
-
-
-def RunSteps(api):
-  # remove demo.
-  api.shutil.remove('foo', 'bar')
-
-  # listdir demo.
-  result = api.shutil.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])
-
-  for name, content in TEST_CONTENTS.iteritems():
-    api.shutil.write('write_%s' % name, 'tmp_file.txt', content)
-    actual_content = api.shutil.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['tmp_base'].join('copytree_example_tmp')
-    api.shutil.makedirs('makedirs', tmp_dir)
-    path = tmp_dir.join('dummy_file')
-    api.shutil.write('write %s' % path, path, content)
-    new_tmp = api.path['tmp_base'].join('copytree_example_tmp2')
-    new_path = new_tmp.join('dummy_file')
-    api.shutil.copytree('copytree', tmp_dir, new_tmp)
-    actual_content = api.shutil.read('read %s' % new_path, new_path,
-                                   test_data=content)
-    assert actual_content == content
-
-    # glob.
-    files = api.shutil.glob(
-        'glob', tmp_dir.join('*'),
-        test_data=[tmp_dir.join('dummy_file')])
-    assert files == [str(tmp_dir.join('dummy_file'))], files
-
-  finally:
-    api.shutil.rmtree(tmp_dir, name='cleanup')
-    api.shutil.rmtree(new_tmp, name='cleanup2')
-
-
-def GenTests(api):
-  yield api.test('basic')