Function check_animation_durations 

pub fn check_animation_durations<D: DecoderConfig + 'static>(
    dec: D,
    bytes: &[u8],
    expected: &[FrameDuration],
) -> Conformance

Verify source timing through borrowed, owned and erased animation decoders. expected names every displayed frame; zero-duration compositing helpers belong in the codec fixture’s expected display sequence, not an inferred count. The sink API returns only OutputInfo, so cannot expose frame timing.