Merge lp:~rockstar/launchpad/bug-520446 into lp:launchpad

[Paul Hummer]

This branch fixes bug #520446. The exception being raised by
IBranch.createMergeProposal through the rest API was inconsistent with the rest
of Launchpad. All I did was catch the exception and re-raise it as a
ValueError.

[Graham Binns (gmb)]

review: Approve (code)

=== modified file 'lib/lp/code/errors.py'
--- lib/lp/code/errors.py	2010-02-24 02:43:52 +0000
+++ lib/lp/code/errors.py	2010-03-10 19:00:50 +0000
@@ -17,6 +17,8 @@
     'WrongBranchMergeProposal',
 ]
 
+from lazr.restful.declarations import webservice_error
+
 
 class BadBranchMergeProposalSearchContext(Exception):
     """The context is not valid for a branch merge proposal search."""
@@ -39,6 +41,7 @@
 
 class BranchMergeProposalExists(InvalidBranchMergeProposal):
     """Raised if there is already a matching BranchMergeProposal."""
+    webservice_error(400) #Bad request.
 
 
 class ReviewNotPending(Exception):

=== modified file 'lib/lp/code/stories/webservice/xx-branchmergeproposal.txt'
--- lib/lp/code/stories/webservice/xx-branchmergeproposal.txt	2010-03-09 17:30:18 +0000
+++ lib/lp/code/stories/webservice/xx-branchmergeproposal.txt	2010-03-10 19:00:50 +0000
@@ -76,6 +76,18 @@
     votes_collection_link:
         u'http://api.launchpad.dev/devel/~.../+merge/.../votes'
 
+If we try and create the merge proposal again, we should get a ValueError.
+
+    >>> print registrant_webservice.named_post(
+    ...     source_url, 'createMergeProposal', target_branch=target_url,
+    ...     prerequisite_branch=prerequisite_url,
+    ...     initial_comment='Merge\nit!', needs_review=True,
+    ...     commit_message='It was merged!\n', reviewers=[reviewer_url],
+    ...     review_types=['green'])
+    HTTP/1.1 500 Internal Server Error ...
+    BranchMergeProposalExists: There is already a branch merge proposal
+    registered for branch ... to land on ... that is still active.
+
 Our review request is listed in the votes collection.
 
     >>> votes = webservice.get(