<svg xmlns='http://www.w3.org/2000/svg'>
  <rect width='100' height='100'>
    <animateColor attributeName="fill" from='#DD0000' by='#0000DD' dur='3s' fill='freeze' />
  </rect>
  <text x='10' y='120'>The rect should animate from red to purple over 3 seconds</text>
</svg>