at: 1.5, expect: 'shape(from 20% 20px, smooth by 25% -5px with 15% 50px, smooth by 15% 35px)'},
      ]);

      test_interpolation({
        property: 'offset-path',
        from: 'shape(from 5% 5px, arc to 15% -15px of 10px 20px, arc by 15% -5px of 30px 30px cw rotate 30deg large, arc to 25% 20px of 10px 5px small)',
        to: 'shape(from 15% 15px, arc to 5% -25px of 20px 30px, arc by 25% -15px of 20px 20px cw rotate 270deg small, arc to 25% 20px of 10px 5px small cw)'
      }, [
        {at: -0.3, expe