FEATURE: adding variable serial batches

This feature changes the scalar value of `serial:` to a list, which
allows users to specify a list of values, so batches can be ramped
up (commonly called "canary" setups):

- hosts: all
  serial: [1, 5, 10, "100%"]
  tasks:
  ...

test/units/utils/test_helpers.py

@@ -0,0 +1,31 @@
+# (c) 2015, Marius Gedminas <marius@gedmin.as>
+#
+# This file is part of Ansible
+#
+# Ansible is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Ansible is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
+
+import unittest
+
+from ansible.utils.helpers import pct_to_int
+
+class TestHelpers(unittest.TestCase):
+
+    def test_pct_to_int(self):
+        self.assertEqual(pct_to_int(1, 100), 1)
+        self.assertEqual(pct_to_int(-1, 100), -1)
+        self.assertEqual(pct_to_int("1%", 10), 1)
+        self.assertEqual(pct_to_int("1%", 10, 0), 0)
+        self.assertEqual(pct_to_int("1", 100), 1)
+        self.assertEqual(pct_to_int("10%", 100), 10)
+