Fix deletion of cached file for policy enforcer

Policy ENFORCER's method 'clear' does not really
delete cached file as written in its docstring.

This commit adds 'delete_cached_file' to fileutils
and makes 'clear' method of ENFORCER use it.

Change-Id: I855d5f2001ac721249217d9fbd782c64af9db874
Closes-Bug: #1340843

4 files changed, 36 insertions, 2 deletions

diff --git a/openstack/common/fileutils.py b/openstack/common/fileutils.py
index 5fc38ab4..bf7df55d 100644
--- a/openstack/common/fileutils.py
+++ b/openstack/common/fileutils.py
@@ -50,8 +50,8 @@ def read_cached_file(filename, force_reload=False):
     """
     global _FILE_CACHE
 
-    if force_reload and filename in _FILE_CACHE:
-        del _FILE_CACHE[filename]
+    if force_reload:
+        delete_cached_file(filename)
 
     reloaded = False
     mtime = os.path.getmtime(filename)
@@ -66,6 +66,17 @@ def read_cached_file(filename, force_reload=False):
     return (reloaded, cache_info['data'])
 
 
+def delete_cached_file(filename):
+    """Delete cached file if present.
+
+    :param filename: filename to delete
+    """
+    global _FILE_CACHE
+
+    if filename in _FILE_CACHE:
+        del _FILE_CACHE[filename]
+
+
 def delete_if_exists(path, remove=os.unlink):
     """Delete a file, but ignore file not found error.
 
diff --git a/openstack/common/policy.py b/openstack/common/policy.py
index b2451ea1..38899150 100644
--- a/openstack/common/policy.py
+++ b/openstack/common/policy.py
@@ -216,6 +216,7 @@ class Enforcer(object):
     def clear(self):
         """Clears Enforcer rules, policy's cache and policy's path."""
         self.set_rules({})
+        fileutils.delete_cached_file(self.policy_path)
         self.default_rule = None
         self.policy_path = None
 
diff --git a/tests/unit/test_fileutils.py b/tests/unit/test_fileutils.py
index c82f16f9..4d9f98c7 100644
--- a/tests/unit/test_fileutils.py
+++ b/tests/unit/test_fileutils.py
@@ -74,6 +74,22 @@ class TestCachedFile(test_base.BaseTestCase):
         self.assertEqual(data, fake_contents)
         self.assertTrue(fresh)
 
+    def test_delete_cached_file(self):
+        filename = '/this/is/a/fake/deletion/of/cached/file'
+        fileutils._FILE_CACHE = {
+            filename: {"data": 1123, "mtime": 1}
+        }
+        self.assertIn(filename, fileutils._FILE_CACHE)
+        fileutils.delete_cached_file(filename)
+        self.assertNotIn(filename, fileutils._FILE_CACHE)
+
+    def test_delete_cached_file_not_exist(self):
+        # We expect that if cached file does not exist no Exception raised.
+        filename = '/this/is/a/fake/deletion/attempt/of/not/cached/file'
+        self.assertNotIn(filename, fileutils._FILE_CACHE)
+        fileutils.delete_cached_file(filename)
+        self.assertNotIn(filename, fileutils._FILE_CACHE)
+
 
 class DeleteIfExists(test_base.BaseTestCase):
     def test_file_present(self):
diff --git a/tests/unit/test_policy.py b/tests/unit/test_policy.py
index 077d966f..33345773 100644
--- a/tests/unit/test_policy.py
+++ b/tests/unit/test_policy.py
@@ -24,6 +24,7 @@ import six
 import six.moves.urllib.parse as urlparse
 import six.moves.urllib.request as urlrequest
 
+from openstack.common import fileutils
 from openstack.common.fixture import config
 from openstack.common.fixture import lockutils
 from openstack.common import jsonutils
@@ -139,11 +140,16 @@ class EnforcerTest(PolicyBaseTestCase):
                           self.enforcer.set_rules,
                           'dummy')
 
+    @mock.patch.object(fileutils, 'delete_cached_file', mock.Mock())
     def test_clear(self):
         # Make sure the rules are reset
         self.enforcer.rules = 'spam'
+        filename = self.enforcer.policy_path
         self.enforcer.clear()
         self.assertEqual(self.enforcer.rules, {})
+        self.assertEqual(self.enforcer.default_rule, None)
+        self.assertEqual(self.enforcer.policy_path, None)
+        fileutils.delete_cached_file.assert_called_once_with(filename)
 
     def test_rule_with_check(self):
         rules_json = """{