px 10px 10px'},
  {at: 0, expect: 'rgb(0, 0, 0) 10px 10px 10px'},
  {at: 0.3, expect: 'rgb(0, 38, 0) 10px 10px 10px'},
  {at: 0.6, expect: 'rgb(0, 77, 0) 10px 10px 10px'},
  {at: 1, expect: 'rgb(0, 128, 0) 10px 10px 10px'},
  {at: 1.5, expect: 'rgb(0, 192, 0) 10px 10px 10px'},
]);

test_interpolation({
  property: 'text-shadow',
  from: 'black 0px 0px 0px',
  to: 'black 1px 1px 1px',
}, [
  {at: -0.3, expect: 'rgb(0, 0, 0) -0.3px -0.3px 0px'},
  {at: 0, expect: 'rgb(0, 0, 0) 0px 0px 0px'},
  {at: 0.3, expec