0043882: It is possible to generate duplicated elements in collection properties of backward compatible state models

diff --git a/web-test/model/application-state/compat/StateBackwardCompatibility-backbone-state.test.js b/web-test/model/application-state/compat/StateBackwardCompatibility-backbone-state.test.js
index ce40b1af..3fde7fa1 100644
--- a/web-test/model/application-state/compat/StateBackwardCompatibility-backbone-state.test.js
+++ b/web-test/model/application-state/compat/StateBackwardCompatibility-backbone-state.test.js
@@ -402,4 +402,38 @@ describe('Backward compatibility: backbone -> state', () => {
       });
     });
   });
+
+  describe('special cases', () => {
+    beforeEach(() => {
+      OB.App.StateAPI.registerBackwardCompatibleModel('Ticket', {});
+      persistence = new OB.App.Class.StatePersistence();
+      const state = new OB.App.Class.State(persistence);
+
+      oldTicket = new Backbone.Model();
+      oldTicket.set('lines', new Backbone.Collection());
+      oldTicket.get('lines').on('add', () => {
+        oldTicket.trigger('doReset');
+      });
+      oldTicket.on('doReset', () => {
+        // do nothing
+      });
+      OB.App.StateBackwardCompatibility.bind(state.Ticket, oldTicket, {
+        resetEvents: ['doReset']
+      });
+    });
+
+    it('listener does not duplicate element into Backbone.Collection property', () => {
+      oldTicket.trigger('change'); // forces backbone -> state propagation
+
+      // add a new line
+      const line = new Backbone.Model({ product: 'transceiver', qty: 1 });
+      oldTicket.get('lines').add(line);
+
+      const stateTicket = persistence.getState().Ticket;
+      expect(stateTicket.lines).toHaveLength(1);
+      expect(stateTicket).toMatchObject({
+        lines: [{ product: 'transceiver', qty: 1 }]
+      });
+    });
+  });
 });