Add unit test to clean_caches()

client/tests/run_isolated_smoke_test.py

Index: client/tests/run_isolated_smoke_test.py
diff --git a/client/tests/run_isolated_smoke_test.py b/client/tests/run_isolated_smoke_test.py
index 2d2316ce48882a4b553bcf8474164713a0bab481..92687387fac3714f32c50bbe6ba3059655a261d1 100755
--- a/client/tests/run_isolated_smoke_test.py
+++ b/client/tests/run_isolated_smoke_test.py
@@ -241,7 +241,7 @@ def tree_modes(root):
   """
   out = {}
   offset = len(root.rstrip('/\\')) + 1
-  out['.'] = oct(os.stat(root).st_mode)
+  out[u'.'] = oct(os.stat(root).st_mode)
   for dirpath, dirnames, filenames in os.walk(root):
     for filename in filenames:
       p = os.path.join(dirpath, filename)
@@ -443,13 +443,13 @@ class RunIsolatedTest(unittest.TestCase):
     _out, _err, returncode = self._run(self._cmd_args(isolated_hash))
     self.assertEqual(0, returncode)
     expected = {
-      '.': (040700, 040700, 040777),
-      'state.json': (0100600, 0100600, 0100666),
+      u'.': (040700, 040700, 040777),
+      u'state.json': (0100600, 0100600, 0100666),
       # The reason for 0100666 on Windows is that the file node had to be
       # modified to delete the hardlinked node. The read only bit is reset on
       # load.
-      file1_hash: (0100400, 0100400, 0100666),
-      isolated_hash: (0100400, 0100400, 0100444),
+      unicode(file1_hash): (0100400, 0100400, 0100666),
+      unicode(isolated_hash): (0100400, 0100400, 0100444),
     }
     self.assertTreeModes(self.cache, expected)
 
@@ -467,7 +467,7 @@ class RunIsolatedTest(unittest.TestCase):
     out, err, returncode = self._run(self._cmd_args(isolated_hash))
     self.assertEqual(0, returncode, (out, err, returncode))
     expected = {
-      '.': (040700, 040700, 040777),
+      u'.': (040700, 040700, 040777),
       u'state.json': (0100600, 0100600, 0100666),
       unicode(file1_hash): (0100400, 0100400, 0100666),
       unicode(isolated_hash): (0100400, 0100400, 0100444),