Merge branch '26437-closed-by' into 'master'

Add issues/:iid/closed_by api endpoint

Closes #26437

See merge request !10511

1 files changed, 35 insertions, 0 deletions

diff --git a/spec/requests/api/issues_spec.rb b/spec/requests/api/issues_spec.rb
index b37be1e0c50..784fd1ff885 100644
--- a/spec/requests/api/issues_spec.rb
+++ b/spec/requests/api/issues_spec.rb
@@ -1344,6 +1344,41 @@ describe API::Issues do
     include_examples 'time tracking endpoints', 'issue'
   end
 
+  describe 'GET :id/issues/:issue_iid/closed_by' do
+    let(:merge_request) do
+      create(:merge_request,
+             :simple,
+             author: user,
+             source_project: project,
+             target_project: project,
+             description: "closes #{issue.to_reference}")
+    end
+
+    before do
+      create(:merge_requests_closing_issues, issue: issue, merge_request: merge_request)
+    end
+
+    it 'returns merge requests that will close issue on merge' do
+      get api("/projects/#{project.id}/issues/#{issue.iid}/closed_by", user)
+
+      expect_paginated_array_response(size: 1)
+    end
+
+    context 'when no merge requests will close issue' do
+      it 'returns empty array' do
+        get api("/projects/#{project.id}/issues/#{closed_issue.iid}/closed_by", user)
+
+        expect_paginated_array_response(size: 0)
+      end
+    end
+
+    it "returns 404 when issue doesn't exists" do
+      get api("/projects/#{project.id}/issues/9999/closed_by", user)
+
+      expect(response).to have_http_status(404)
+    end
+  end
+
   def expect_paginated_array_response(size: nil)
     expect(response).to have_http_status(200)
     expect(response).to include_pagination_headers