Extensions Docs Server: Uniform handling of file not found errors

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

 # 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
 
+from file_system import FileNotFoundError
 import third_party.json_schema_compiler.model as model
 from docs_server_utils import SanitizeAPIName
 
 class APIListDataSource(object):
   """ This class creates a list of chrome.* APIs and chrome.experimental.* APIs
   that are used in the api_index.html and experimental.html pages.
   """
   def __init__(self, cache_builder, file_system, api_path, public_path):
     self._cache = cache_builder.build(self._ListAPIs)
     self._file_system = file_system
@@ skipping 28 matching lines @@
       'apps': self._GetAPIsInSubdirectory(api_names, 'apps'),
       'extensions': self._GetAPIsInSubdirectory(api_names, 'extensions')
     }
 
   def __getitem__(self, key):
     return self.get(key)
 
   def get(self, key):
     try:
       return self._cache.GetFromFileListing(self._api_path)[key]
-    except Exception as e:
+    except FileNotFoundError:

[not at google - send to devlin, 2012/08/10 06:12:16]

log error?

[cduvall, 2012/08/10 17:25:16]

Done.

[not at google - send to devlin, 2012/08/12 22:22:58]

By the same logic as ApiDataSource we shouldn't catch this error here. Let it be
an error so that the integration tests can catch it.

Though in this case I'm not sure FileNotFoundError is the correct error to
raise. The apps/extensions directory not being present would imply a programming
error (since we're controlling the data that calls this). So perhaps turn this
error into a ValueError (with an appropriate message, and constructed with the
old error of course... presuming that's possible).

[cduvall, 2012/08/13 18:44:05]

Used the error as a string plus a more specific message, I think that's the best
way to do it in python.

       return None