Refactor the devserver to make it easier to control caching

chrome/common/extensions/docs/server2/caching_file_system_test.py

+#!/usr/bin/env python
+# Copyright (c) 2012 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 os
+import sys
+import unittest
+
+from caching_file_system import CachingFileSystem
+from file_system import FileSystem, StatInfo
+from future import Future
+from in_memory_object_store import InMemoryObjectStore
+from local_file_system import LocalFileSystem
+from test_file_system import TestFileSystem
+
+def _CreateLocalFs():
+  return LocalFileSystem(
+      os.path.join(sys.path[0], 'test_data', 'file_system'))
+
+class CachingFileSystemTest(unittest.TestCase):
+  def testReadFiles(self):
+    file_system = CachingFileSystem(_CreateLocalFs())
+    expected = {
+      './test1.txt': 'test1\n',
+      './test2.txt': 'test2\n',
+      './test3.txt': 'test3\n',
+    }
+    self.assertEqual(
+        expected,
+        file_system.Read(['./test1.txt', './test2.txt', './test3.txt']).Get())
+
+  def testListDir(self):
+    file_system = CachingFileSystem(_CreateLocalFs())
+    expected = ['dir/'] + ['file%d.html' % i for i in range(7)]
+    file_system._read_object_store.Set(
+        'list/',
+        (expected, file_system.Stat('list/').version))
+    self.assertEqual(expected, sorted(file_system.ReadSingle('list/')))
+
+    expected.remove('file0.html')
+    file_system._read_object_store.Set(
+        'list/',
+        (expected, file_system.Stat('list/').version))
+    self.assertEqual(expected, sorted(file_system.ReadSingle('list/')))
+
+  def testCaching(self):
+    fake_fs = TestFileSystem({
+      'bob': {
+        'bob0': 'bob/bob0 contents',
+        'bob1': 'bob/bob1 contents',
+        'bob2': 'bob/bob2 contents',
+        'bob3': 'bob/bob3 contents',
+      }
+    })
+    file_system = CachingFileSystem(fake_fs)
+
+    self.assertEqual('bob/bob0 contents', file_system.ReadSingle('bob/bob0'))
+    self.assertTrue(fake_fs.CheckAndReset(read_count=1, stat_count=1))
+
+    # Resource has been cached, so test resource is not re-fetched.
+    self.assertEqual('bob/bob0 contents', file_system.ReadSingle('bob/bob0'))
+    self.assertTrue(fake_fs.CheckAndReset())
+
+    # Test if the Stat version is the same the resource is not re-fetched.
+    file_system._stat_object_store.Delete('bob/bob0')
+    self.assertEqual('bob/bob0 contents', file_system.ReadSingle('bob/bob0'))
+    self.assertTrue(fake_fs.CheckAndReset(stat_count=1))
+
+    # Test if there is a newer version, the resource is re-fetched.
+    file_system._stat_object_store.Delete('bob/bob0')
+    fake_fs.IncrementStat();
+    self.assertEqual('bob/bob0 contents', file_system.ReadSingle('bob/bob0'))
+    self.assertTrue(fake_fs.CheckAndReset(read_count=1, stat_count=1))
+
+    # Test directory and subdirectory stats are cached.
+    file_system._stat_object_store.Delete('bob/bob0')
+    file_system._read_object_store.Delete('bob/bob0')
+    file_system._stat_object_store.Delete('bob/bob1')
+    fake_fs.IncrementStat();
+    self.assertEqual('bob/bob1 contents', file_system.ReadSingle('bob/bob1'))
+    self.assertEqual('bob/bob0 contents', file_system.ReadSingle('bob/bob0'))
+    self.assertTrue(fake_fs.CheckAndReset(read_count=2, stat_count=1))
+    self.assertEqual('bob/bob1 contents', file_system.ReadSingle('bob/bob1'))
+    self.assertTrue(fake_fs.CheckAndReset())
+
+    # Test a more recent parent directory doesn't force a refetch of children.
+    file_system._read_object_store.Delete('bob/bob0')
+    file_system._read_object_store.Delete('bob/bob1')
+    self.assertEqual('bob/bob1 contents', file_system.ReadSingle('bob/bob1'))
+    self.assertEqual('bob/bob2 contents', file_system.ReadSingle('bob/bob2'))
+    self.assertEqual('bob/bob3 contents', file_system.ReadSingle('bob/bob3'))
+    self.assertTrue(fake_fs.CheckAndReset(read_count=3))
+    fake_fs.IncrementStat(path='bob/')
+    self.assertEqual('bob/bob1 contents', file_system.ReadSingle('bob/bob1'))
+    self.assertEqual('bob/bob2 contents', file_system.ReadSingle('bob/bob2'))
+    self.assertEqual('bob/bob3 contents', file_system.ReadSingle('bob/bob3'))
+    self.assertTrue(fake_fs.CheckAndReset())
+
+    file_system._stat_object_store.Delete('bob/bob0')
+    self.assertEqual('bob/bob0 contents', file_system.ReadSingle('bob/bob0'))
+    self.assertTrue(fake_fs.CheckAndReset(read_count=1, stat_count=1))
+    self.assertEqual('bob/bob0 contents', file_system.ReadSingle('bob/bob0'))
+    self.assertTrue(fake_fs.CheckAndReset())
+
+if __name__ == '__main__':
+  unittest.main()