Code review comment for lp:~adeuring/launchpad/bug-612779

Hi Māris,

Agreed, the word "always" is questionable in this context. But a comparison "before/after" is a test is a bit difficult, I think. OK, I could monkey patch the view_class attribute of BugAttachmentFileNavigation so that it is again StreamOrRedirectLibraryFileAliasView, but I think a better comment and an
assertIsInstance() is sufficient:

    def test_content_disposition_of_restricted_file(self):
        # The content of restricted Librarian files for bug attachments
        # is served by instances of SafeStreamOrRedirectLibraryFileAliasView
        # which set the content disposition header of the HTTP response for
        # to "attachment".
        lfa_with_parent = getMultiAdapter(
            (self.bugattachment.libraryfile, self.bugattachment),
            ILibraryFileAliasWithParent)
        lfa_with_parent.restricted = True
        self.bug.setPrivate(True, self.bug_owner)
        transaction.commit()
        request = LaunchpadTestRequest()
        request.setTraversalStack(['foo.txt'])
        navigation = BugAttachmentFileNavigation(self.bugattachment, request)
        view = navigation.publishTraverse(request, '+files')
        next_view, traversal_path = view.browserDefault(request)
        self.assertIsInstance(
            next_view, SafeStreamOrRedirectLibraryFileAliasView)
        next_view()
        self.assertEqual(
            'attachment', request.response.getHeader('Content-Disposition'))