Merge branch 'jej-use-issuable-finder-instead-of-access-check' into 'security'

Replace issue access checks with use of IssuableFinder

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

### Issue lookup with access check

Using `visible_to_user` likely makes these security issues too. See [Code smells](#code-smells).

- [x] :vertical_traffic_light: app/finders/notes_finder.rb:15 [`visible_to_user`]
- [x] :traffic_light: app/views/layouts/nav/_project.html.haml:73 [`visible_to_user`] [`.count`]
- [x] :white_check_mark: app/services/merge_requests/build_service.rb:84 [`issue.try(:confidential?)`]
- [x] :white_check_mark: lib/api/issues.rb:112 [`visible_to_user`]
  - CHANGELOG: Prevented API returning issues set to 'Only team members' to everyone
- [x] :white_check_mark: lib/api/helpers.rb:126 [`can?(current_user, :read_issue, issue)`] Maybe here too?
- [x] :white_check_mark: lib/gitlab/search_results.rb:53 [`visible_to_user`]

### Previous discussions
- [ ] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#b2ff264eddf9819d7693c14ae213d941494fe2b3_128_126
- [ ] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#7b6375270d22f880bdcb085e47b519b426a5c6c7_87_87

See merge request !2031

1 files changed, 13 insertions, 3 deletions

diff --git a/spec/models/project_spec.rb b/spec/models/project_spec.rb
index da38254d1bc..8abcce42ce0 100644
--- a/spec/models/project_spec.rb
+++ b/spec/models/project_spec.rb
@@ -361,10 +361,15 @@ describe Project, models: true do
   describe '#get_issue' do
     let(:project) { create(:empty_project) }
     let!(:issue)  { create(:issue, project: project) }
+    let(:user)    { create(:user) }
+
+    before do
+      project.team << [user, :developer]
+    end
 
     context 'with default issues tracker' do
       it 'returns an issue' do
-        expect(project.get_issue(issue.iid)).to eq issue
+        expect(project.get_issue(issue.iid, user)).to eq issue
       end
 
       it 'returns count of open issues' do
@@ -372,7 +377,12 @@ describe Project, models: true do
       end
 
       it 'returns nil when no issue found' do
-        expect(project.get_issue(999)).to be_nil
+        expect(project.get_issue(999, user)).to be_nil
+      end
+
+      it "returns nil when user doesn't have access" do
+        user = create(:user)
+        expect(project.get_issue(issue.iid, user)).to eq nil
       end
     end
 
@@ -382,7 +392,7 @@ describe Project, models: true do
       end
 
       it 'returns an ExternalIssue' do
-        issue = project.get_issue('FOO-1234')
+        issue = project.get_issue('FOO-1234', user)
         expect(issue).to be_kind_of(ExternalIssue)
         expect(issue.iid).to eq 'FOO-1234'
         expect(issue.project).to eq project