[Predator] Add local cache for get command output.

appengine/findit/common/test/cache_decorator_test.py

Index: appengine/findit/common/test/cache_decorator_test.py
diff --git a/appengine/findit/common/test/cache_decorator_test.py b/appengine/findit/common/test/cache_decorator_test.py
index a3a2fd467c7e0b29790a484bd2e45b31d958614c..092507caef14607863288cfe040bd0f1eed46236 100644
--- a/appengine/findit/common/test/cache_decorator_test.py
+++ b/appengine/findit/common/test/cache_decorator_test.py
@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import os
 import pickle
 import zlib
 
@@ -11,6 +12,8 @@ from testing_utils import testing
 
 from common import cache_decorator
 
+_LOCAL_CACHE_TEST_DIR = os.path.join(os.path.expanduser('~'), '.test_cache')

[Martin Barbella, 2016/10/26 23:21:20]

Could you use https://pypi.python.org/pypi/pyfakefs here? I really don't like
the idea of having tests actually write to this directory. It can be fairly
painful to maintain, and could be nondeterministic between runs for many, many
reasons (cleanup and all of the usual IO problems).

[Sharu Jiang, 2016/10/27 21:59:05]

The pyfakefs is third_party libs, use mock instead.

+
 
 class _DummyCacher(cache_decorator.Cacher):
   def __init__(self, cached_data):
@@ -162,3 +165,11 @@ class CacheDecoratorTest(testing.AppengineTestCase):
     a2 = A('http://test', 5)
     self.assertEqual('http://test/p1', a2.Func('p1'))
     self.assertEqual(0, a2.runs)
+
+  def testLocalCacher(self):
+    cacher = cache_decorator.LocalCacher(cache_dir=_LOCAL_CACHE_TEST_DIR)
+    cacher.Set('a', 'b')
+    self.assertEqual('b', cacher.Get('a'))
+    cacher.Set('c', 'd')
+    self.assertEqual('d', cacher.Get('c'))
+    self.assertIsNone(cacher.Get('uncached_key'))