[Predator] Add local cache for get command output.

appengine/findit/util_scripts/test/local_cache_test.py

Index: appengine/findit/util_scripts/test/local_cache_test.py
diff --git a/appengine/findit/util_scripts/test/local_cache_test.py b/appengine/findit/util_scripts/test/local_cache_test.py
new file mode 100644
index 0000000000000000000000000000000000000000..b8eff03cefde6c993d2486086fd0cd633c4b979d
--- /dev/null
+++ b/appengine/findit/util_scripts/test/local_cache_test.py
@@ -0,0 +1,32 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import __builtin__
+import mock
+import os
+import pickle
+import zlib
+
+from testing_utils import testing
+
+import local_cache
+
+
+class LocalCacheTest(testing.AppengineTestCase):
+
+  def testLocalCacher(self):
+    fake_dir = 'fake_dir'
+    cacher = local_cache.LocalCacher(cache_dir=fake_dir)
+    def _MockPathExists(path, *_):
+      return False if path == os.path.join(
+          fake_dir, 'uncached_key') else True
+    self.mock(os.path, 'exists', _MockPathExists)
+
+    value = 'val'
+    with mock.patch('__builtin__.open', mock.mock_open(
+        read_data=zlib.compress(pickle.dumps(value)))) as m:
+      cacher.Set('a', 'b')
+      m.assert_called_once_with(os.path.join(fake_dir, 'a'), 'wb')
+      self.assertEqual(value, cacher.Get('key'))
+      self.assertIsNone(cacher.Get('uncached_key'))