Fix remove_source_branch merge request API handling

Users attempting to set merge requests to `remove_source_branch` to
`false` would encounter an Error 500 because the UpdateService and API
checked `present?`, which would always return `false`. We now just
use `has_key?` to decide whether the parameter is present.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/60530

1 files changed, 26 insertions, 0 deletions

diff --git a/spec/requests/api/merge_requests_spec.rb b/spec/requests/api/merge_requests_spec.rb
index 45818edbf68..5c94a87529b 100644
--- a/spec/requests/api/merge_requests_spec.rb
+++ b/spec/requests/api/merge_requests_spec.rb
@@ -1596,6 +1596,32 @@ describe API::MergeRequests do
   end
 
   describe "PUT /projects/:id/merge_requests/:merge_request_iid" do
+    context 'updates force_remove_source_branch properly' do
+      it 'sets to false' do
+        merge_request.update(merge_params: { 'force_remove_source_branch' => true } )
+
+        expect(merge_request.force_remove_source_branch?).to be_truthy
+
+        put api("/projects/#{project.id}/merge_requests/#{merge_request.iid}", user), params: { state_event: "close", remove_source_branch: false }
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(json_response['state']).to eq('closed')
+        expect(json_response['force_remove_source_branch']).to be_falsey
+      end
+
+      it 'sets to true' do
+        merge_request.update(merge_params: { 'force_remove_source_branch' => false } )
+
+        expect(merge_request.force_remove_source_branch?).to be_falsey
+
+        put api("/projects/#{project.id}/merge_requests/#{merge_request.iid}", user), params: { state_event: "close", remove_source_branch: true }
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(json_response['state']).to eq('closed')
+        expect(json_response['force_remove_source_branch']).to be_truthy
+      end
+    end
+
     context "to close a MR" do
       it "returns merge_request" do
         put api("/projects/#{project.id}/merge_requests/#{merge_request.iid}", user), params: { state_event: "close" }