[recipe_modules/file] add real file module to engine.

recipe_modules/file/examples/copytree.py

Index: recipe_modules/file/examples/copytree.py
diff --git a/recipe_modules/file/examples/copytree.py b/recipe_modules/file/examples/copytree.py
new file mode 100644
index 0000000000000000000000000000000000000000..4c9ba1349fd87110854cbbe1edbccb4fe2525024
--- /dev/null
+++ b/recipe_modules/file/examples/copytree.py
@@ -0,0 +1,49 @@
+# Copyright 2017 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.
+
+DEPS = [
+  "file",
+  "path",
+]
+
+
+def RunSteps(api):
+  file_names = ['a', 'aa', 'b', 'bb', 'c', 'cc']
+
+  dest = api.path['start_dir'].join('some dir')
+  api.file.ensure_directory('ensure "some dir"', dest)
+  for fname in file_names:
+    api.file.write_text('write %s' % fname, dest.join(fname), fname)
+
+  dest2 = api.path['start_dir'].join('some other dir')
+  api.file.rmtree('make sure dest is gone', dest2)
+  api.file.copytree('copy it', dest, dest2)
+
+  names = api.file.listdir('list new dir', dest2, file_names)
+  assert names == file_names, names
+
+  paths = api.file.glob_paths('glob *a', dest2.join('*a'),
+                              [dest2.join(x) for x in ('a', 'aa')])
+  assert paths == [dest2.join('a'), dest2.join('aa')], paths
+
+  for pth in paths:
+    assert api.file.read_text('read %s' % pth, pth, api.path.basename(pth))
+
+  api.file.remove('rm a', dest2.join('a'))
+  paths = api.file.glob_paths('glob *a', dest2.join('*a'), [dest2.join('aa')])
+  assert paths == [dest2.join('aa')], paths
+
+  api.file.rmglob('rm b*', dest2, 'b*')
+  new_names = ['aa', 'c', 'cc']
+  names = api.file.listdir('list new dir', dest2, new_names)
+  assert names == new_names, names
+
+  api.file.rmcontents('remove "some other dir/*"', dest2)
+  assert api.path.exists(dest2), dest2
+
+
+
+def GenTests(api):
+  yield api.test('basic')
+