Clean up hit_store to use stat permissions

Change the os.chmod() call to use the stat constants
rather than 0o600, and add a unit test to make sure that
the permissions are being set properly.

Bug: 27718898
Test: `python test_runner.py` passes
Change-Id: Ifea8b99e21f4914b8235733e575d948d5d183b86

2 files changed, 30 insertions, 1 deletions

diff --git a/cli/lib/metrics/hit_store.py b/cli/lib/metrics/hit_store.py
index e8e0e55..8e341b4 100644
--- a/cli/lib/metrics/hit_store.py
+++ b/cli/lib/metrics/hit_store.py
@@ -17,6 +17,7 @@
 
 import os
 import sqlite3
+import stat
 
 from core import util
 
@@ -47,7 +48,7 @@ class Backup(object):
         self._conn.execute(
             'CREATE TABLE IF NOT EXISTS %s (unused)' % self._table)
         if self._path != ':memory:':
-            os.chmod(self._path, 0o600)
+            os.chmod(self._path, stat.S_IRUSR | stat.S_IWUSR)
         self._initialized = True
 
     def _add_fields(self, fields):
diff --git a/cli/lib/metrics/hit_store_unittest.py b/cli/lib/metrics/hit_store_unittest.py
index 5ab9a4f..a49dcd6 100644
--- a/cli/lib/metrics/hit_store_unittest.py
+++ b/cli/lib/metrics/hit_store_unittest.py
@@ -17,6 +17,10 @@
 """Unittests for hit_store.py."""
 
 
+import os
+import shutil
+import stat
+import tempfile
 import unittest
 
 from metrics import hit_store
@@ -43,3 +47,27 @@ class HitStoreTest(unittest.TestCase):
         self.hit_store.save(field3)
         retrieved = self.hit_store.retrieve_all()
         self.assertEqual(retrieved, [field3])
+
+
+class HitStoreSetupTest(unittest.TestCase):
+    """Test that a hit store is set up correctly."""
+
+    def setUp(self):
+        """Set up the test."""
+        self.tmpdir = tempfile.mkdtemp()
+        self.db = os.path.join(self.tmpdir, 'test.db')
+        self.hit_store = hit_store.Backup(file_path=self.db)
+
+        # pylint: disable=protected-access
+        self.hit_store._setup()
+
+    def tearDown(self):
+        """Clean up after the test."""
+        shutil.rmtree(self.tmpdir)
+
+    def test_file_permissions(self):
+        """Test that the database file has the correct permissions."""
+        self.assertTrue(os.path.isfile(self.db))
+        stat_ = os.stat(self.db)
+        permissions = oct(stat_.st_mode & 0o777)
+        self.assertEqual(permissions, oct(stat.S_IRUSR | stat.S_IWUSR))