[IMP] Cleanup and refactoring of exception handling

Unify and refactor exception handling in framework and addons.

The generic `except_osv` is now deprecated, and replaced by more specialized exception subtypes:
 - `UserError` (renamed from Warning, as it conflicts with the built-in `Warning`) raised when a non-technical error occurs during a business operation. It could be a missing information in the data provided by the user, or a misconfiguration.
 - `AccessError`: raised when any operation is denied because the user conducting it does not have the required access rights.
 - `AccessDenied`: raised when an operation that requires authenticated access is attempted via an unauthenticated request.
 - `MissingError`: raised when an operation is attempted on a record that does not exist.
 - `ValidationError`: raised when an operation violates a SQL or Python constraint.
 - All other exceptions are internal errors due to a system problem or bug, and raised untouched to the client-side, which should display a traceback.

All exceptions take a single message argument.

The `test_exceptions` module has been updated to showcase both new and old (deprecated) exceptions.

A great many old `except_osv` had a useless title with "Error!" or "Warning", those have been removed, as this is handled by the client-side widget that displays the messages.

This commit introduces a more consistent policy for logging errors and warnings:
 - All messages that do not require administrator attention should be logged at INFO level or lower. This includes all errors that are notified to the user in a friendly manner, even for access right problems or validation errors during business operations.
 - All messages that indicate a likely misconfiguration or malicious use by the users should be logged at WARNING level, as they typically require administrator attention.
 - All other unhandled internal errors cannot typically be handled by the user and should be logged at ERROR or higher level, as they require immediate administrator attention.

2 files changed, 7 insertions, 7 deletions

diff --git a/addons/website_forum/models/forum.py b/addons/website_forum/models/forum.py
index 9ad2bdd49da..b8fe561d4a5 100644
--- a/addons/website_forum/models/forum.py
+++ b/addons/website_forum/models/forum.py
@@ -13,7 +13,7 @@ from openerp import modules
 from openerp import tools
 from openerp import SUPERUSER_ID
 from openerp.addons.website.models.website import slug
-from openerp.exceptions import Warning
+from openerp.exceptions import UserError
 
 _logger = logging.getLogger(__name__)
 
@@ -297,7 +297,7 @@ class Post(models.Model):
         post = super(Post, self.with_context(mail_create_nolog=True)).create(vals)
         # deleted or closed questions
         if post.parent_id and (post.parent_id.state == 'close' or post.parent_id.active is False):
-            raise Warning(_('Posting answer on a [Deleted] or [Closed] question is not possible'))
+            raise UserError(_('Posting answer on a [Deleted] or [Closed] question is not possible'))
         # karma-based access
         if not post.parent_id and not post.can_ask:
             raise KarmaError('Not enough karma to create a new question')
@@ -574,7 +574,7 @@ class Vote(models.Model):
 
         # own post check
         if vote.user_id.id == vote.post_id.create_uid.id:
-            raise Warning('Not allowed to vote for its own post')
+            raise UserError(_('Not allowed to vote for its own post'))
         # karma check
         if vote.vote == '1' and not vote.post_id.can_upvote:
             raise KarmaError('Not enough karma to upvote.')
@@ -594,7 +594,7 @@ class Vote(models.Model):
             for vote in self:
                 # own post check
                 if vote.user_id.id == vote.post_id.create_uid.id:
-                    raise Warning('Not allowed to vote for its own post')
+                    raise UserError(_('Not allowed to vote for its own post'))
                 # karma check
                 if (values['vote'] == '1' or vote.vote == '-1' and values['vote'] == '0') and not vote.post_id.can_upvote:
                     raise KarmaError('Not enough karma to upvote.')
diff --git a/addons/website_forum/tests/test_forum.py b/addons/website_forum/tests/test_forum.py
index 7ca4c2a69ab..50ce7055ced 100644
--- a/addons/website_forum/tests/test_forum.py
+++ b/addons/website_forum/tests/test_forum.py
@@ -2,7 +2,7 @@
 
 from openerp.addons.website_forum.tests.common import KARMA, TestForumCommon
 from openerp.addons.website_forum.models.forum import KarmaError
-from openerp.exceptions import Warning, AccessError
+from openerp.exceptions import UserError, AccessError
 from openerp.tools import mute_logger
 
 
@@ -67,7 +67,7 @@ class TestForum(TestForumCommon):
             'parent_id': self.post.id})
 
         # upvote its own post
-        with self.assertRaises(Warning):
+        with self.assertRaises(UserError):
             emp_answer.vote(upvote=True)
 
         # not enough karma
@@ -90,7 +90,7 @@ class TestForum(TestForumCommon):
             'parent_id': self.post.id})
 
         # downvote its own post
-        with self.assertRaises(Warning):
+        with self.assertRaises(UserError):
             emp_answer.vote(upvote=False)
 
         # not enough karma