Merge branch 'jej-note-search-uses-finder' into 'security'

Fix missing Note access checks in by moving Note#search to updated NoteFinder

Split from !2024 to partially solve https://gitlab.com/gitlab-org/gitlab-ce/issues/23867

## Which fixes are in this MR?

:warning: - Potentially untested  
:bomb: - No test coverage  
:traffic_light: - Test coverage of some sort exists (a test failed when error raised)  
:vertical_traffic_light: - Test coverage of return value (a test failed when nil used)  
:white_check_mark: - Permissions check tested

### Note lookup without access check

- [x] :white_check_mark: app/finders/notes_finder.rb:13 :download_code check
- [x] :white_check_mark: app/finders/notes_finder.rb:19 `SnippetsFinder`
- [x] :white_check_mark: app/models/note.rb:121 [`Issue#visible_to_user`]
- [x] :white_check_mark: lib/gitlab/project_search_results.rb:113
  - This is the only use of `app/models/note.rb:121` above, but importantly has no access checks at all. This means it leaks MR comments and snippets when those features are `team-only` in addition to the issue comments which would be fixed by `app/models/note.rb:121`.
  - It is only called from SearchController where `can?(current_user, :download_code, @project)` is checked, so commit comments are not leaked.

### Previous discussions
- [x] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#b915c5267a63628b0bafd23d37792ae73ceae272_13_13 `: download_code` check on commit
- [x] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#b915c5267a63628b0bafd23d37792ae73ceae272_19_19 `SnippetsFinder` should be used
  - `SnippetsFinder` should check if the snippets feature is enabled -> https://gitlab.com/gitlab-org/gitlab-ce/issues/25223

###  Acceptance criteria met?
- [x] Tests added for new code
- [x] TODO comments removed
- [x] Squashed and removed skipped tests
- [x] Changelog entry
- [ ] State Gitlab versions affected and issue severity in description
- [ ] Create technical debt issue for NotesFinder.
  - Either split into `NotesFinder::ForTarget` and `NotesFinder::Search` or consider object per notable type such as `NotesFinder::OnIssue`. For the first option could create `NotesFinder::Base` which is either inherited from or which can be included in the other two.
  - Avoid case statement anti-pattern in this finder with use of `NotesFinder::OnCommit` etc. Consider something on the finder for this? `Model.finder(user, project)`
  - Move `inc_author` to the controller, and implement `related_notes` to replace `non_diff_notes`/`mr_and_commit_notes`

See merge request !2035

1 files changed, 3 insertions, 3 deletions

diff --git a/spec/models/merge_request_spec.rb b/spec/models/merge_request_spec.rb
index 8b730be91fd..1b71d00eb8f 100644
--- a/spec/models/merge_request_spec.rb
+++ b/spec/models/merge_request_spec.rb
@@ -205,7 +205,7 @@ describe MergeRequest, models: true do
     end
   end
 
-  describe "#mr_and_commit_notes" do
+  describe "#related_notes" do
     let!(:merge_request) { create(:merge_request) }
 
     before do
@@ -217,7 +217,7 @@ describe MergeRequest, models: true do
 
     it "includes notes for commits" do
       expect(merge_request.commits).not_to be_empty
-      expect(merge_request.mr_and_commit_notes.count).to eq(2)
+      expect(merge_request.related_notes.count).to eq(2)
     end
 
     it "includes notes for commits from target project as well" do
@@ -225,7 +225,7 @@ describe MergeRequest, models: true do
                               project: merge_request.target_project)
 
       expect(merge_request.commits).not_to be_empty
-      expect(merge_request.mr_and_commit_notes.count).to eq(3)
+      expect(merge_request.related_notes.count).to eq(3)
     end
   end