px)'},
        {at: 1, expect: 'shape(from calc(0% + 15px) 15px, smooth to calc(0% + 20px) 0px with calc(0% + 10px) 60px, smooth to calc(0% + 20px) 30px)'},
        {at: 1.5, expect: 'shape(from calc(-2.5% + 22.5px) 20px, smooth to calc(-5% + 30px) -5px with calc(0% + 15px) 50px, smooth to calc(-15% + 30px) 35px)'},
      ]);

      test_interpolation({
        property: 'offset-path',
        from: 'path("M 5 5 s 0 80 10 10 t 30 20")',
        to: 'shape(from 15px 15px, smooth by 20px 0px with 10px 60px, s