Revert "Add hacking check to prevent assert_called_once"

This reverts commit 9400cee06f.

Calling assert_called_once seems to fail as expected
using mock 1.3.0.

Change-Id: Ie382989e03b31564a3bfb4e8d010a8a93467f71b

HACKING.rst

@@ -30,7 +30,6 @@ Cinder Specific Commandments
 - [C311] Check for proper naming and usage in option registration.
 - [C312] Check that assertIsNone(value) is used and not assertEqual(None, value).
 - [C313] Check that assertTrue(value) is used and not assertEqual(True, value).
-- [C314] Check for use of invalid mock.assert_called_once().
 
 General
 -------

cinder/hacking/checks.py

@@ -504,15 +504,6 @@ def validate_assertTrue(logical_line):
         yield(0, msg)
 
 
-def no_assert_called_once(logical_line, filename):
-    if "cinder/tests" not in filename or "test_hacking" in filename:
-        return
-    msg = ("C314: assert_called_once is not a valid mock assertion, "
-           "use assert_equal(1, mocked.call_count) instead.")
-    if 'assert_called_once(' in logical_line:
-        yield (0, msg)
-
-
 def factory(register):
     register(no_vi_headers)
     register(no_translate_debug_logs)
@@ -535,4 +526,3 @@ def factory(register):
     register(no_test_log)
     register(validate_assertIsNone)
     register(validate_assertTrue)
-    register(no_assert_called_once)

cinder/tests/unit/test_hacking.py

@@ -448,9 +448,3 @@ class HackingTestCase(test.TestCase):
     def test_no_test_log(self, first, second, third, fourth):
         self.assertEqual(first, len(list(checks.no_test_log(
             "%s('arg')" % second, third, fourth))))
-
-    def test_no_assert_called_once(self):
-        self.assertEqual(1, len(list(checks.no_assert_called_once(
-            "masker.assert_called_once(", "cinder/tests/unit/fake.py"))))
-        self.assertEqual(0, len(list(checks.no_assert_called_once(
-            "masker.assert_called_once_with(", "cinder/tests/unit/fake.py"))))