Add file.filesizes to recipe engine core modules.

recipe_modules/file/api.py

Index: recipe_modules/file/api.py
diff --git a/recipe_modules/file/api.py b/recipe_modules/file/api.py
index ca9ebb66bca268c6e2714b56352c00e7ab9a3f45..a79960f7cf3c043223662da84396e1f8de303f4d 100644
--- a/recipe_modules/file/api.py
+++ b/recipe_modules/file/api.py
@@ -224,6 +224,28 @@ class FileApi(recipe_api.RecipeApi):
       name, ['ensure-directory', '--mode', oct(mode), dest])
     self.m.path.mock_add_paths(dest)
 
+  def filesizes(self, name, *files, **kwargs):
+    """Returns list of filesizes for a given files.

[Michael Achenbach, 2017/08/07 07:37:40]

s/a/the

[tandrii(chromium), 2017/08/07 10:59:49]

Done.

+
+    Args:
+      * name (str) - The name of the step.
+      * files (Path) - One or more paths to files.
+
+    Returns list[int], size of each file in bytes.
+    """
+    test_data = kwargs.pop('test_data', ())

[Michael Achenbach, 2017/08/07 07:37:39]

How about some better fake data when no test data is provided? E.g. some fake
sizes that fit to the number of files?

[tandrii(chromium), 2017/08/07 10:59:49]

Done.

+    assert not kwargs, 'only test_data kwarg allowed'
+    for f in files:
+      self.m.path.assert_absolute(f)
+    result = self._run(
+      name, ['filesizes'] + list(files),
+      lambda: self.test_api.filesizes(test_data),
+      self.m.raw_io.output_text())
+    ret = map(int, result.stdout.strip().splitlines())
+    result.presentation.logs['filesizes'] = ['%s: \t%d' % fs
+                                             for fs in zip(files, ret)]
+    return ret
+
   def rmtree(self, name, source):
     """Recursively removes a directory.