Remove absorbing org from merging organisations list

app/controllers/merge_requests_controller.rb

@@ -21,12 +21,9 @@ class MergeRequestsController < ApplicationController
     validate_response
 
     if @merge_request.errors.blank? && @merge_request.update(merge_request_params)
-      if page == "merging_organisations"
+      add_merging_organsations if page == "merging_organisations"
-        new_merging_org_ids = params["merge_request"]["new_merging_org_ids"].split(" ")
+      remove_absorbing_org_from_merging_organisations if page == "absorbing_organisation" && @merge_request.absorbing_organisation_id.present?
-        new_merging_org_ids.each do |org_id|
+
-          MergeRequestOrganisation.create!(merge_request: @merge_request, merging_organisation_id: org_id)
-        end
-      end
       redirect_to next_page_path
     else
       render previous_template, status: :unprocessable_entity
@@ -176,4 +173,17 @@ private
     parsed_params = CGI.parse(query_params)
     parsed_params[query_param]&.first
   end
+
+  def add_merging_organsations
+    new_merging_org_ids = params["merge_request"]["new_merging_org_ids"].split(" ")
+    new_merging_org_ids.each do |org_id|
+      MergeRequestOrganisation.create!(merge_request: @merge_request, merging_organisation_id: org_id)
+    end
+  end
+
+  def remove_absorbing_org_from_merging_organisations
+    if @merge_request.merge_request_organisations.where(merging_organisation_id: @merge_request.absorbing_organisation_id).exists?
+      MergeRequestOrganisation.find_by(merge_request: @merge_request, merging_organisation_id: @merge_request.absorbing_organisation_id).destroy!
+    end
+  end
 end

spec/requests/merge_requests_controller_spec.rb

@@ -294,6 +294,25 @@ RSpec.describe MergeRequestsController, type: :request do
             expect(page).to have_button("Save changes")
           end
         end
+
+        context "when absorbing_organisation_id set to one of the merging organisations" do
+          let(:merge_request) { MergeRequest.create!(requesting_organisation: organisation) }
+          let(:params) do
+            { merge_request: { absorbing_organisation_id: other_organisation.id, page: "absorbing_organisation" } }
+          end
+
+          let(:request) do
+            MergeRequestOrganisation.create!(merge_request_id: merge_request.id, merging_organisation_id: other_organisation.id)
+            patch "/merge-request/#{merge_request.id}", headers:, params:
+          end
+
+          it "removes organisation from merge request organisations" do
+            request
+
+            merge_request.reload
+            expect(merge_request.merging_organisations.count).to eq(0)
+          end
+        end
       end
 
       describe "from merge_date page" do