   });

          filter.path = 'foo.bar';
        });

        it('should not warn about undefined values with defined parent property', done => {
          const _warn = console.warn;
          const spy = console.warn = sinon.spy();

          listenOnce(filter, 'filter-changed', e => {
            setTimeout(() => {
              console.warn = _warn;
              expect(spy.called).to.be.false;
              done();
            });
          });

          filter.path = 'name.foo';
        });

      