Function check_incremental_decoder 

pub fn check_incremental_decoder<F, O>(
    new_decoder: F,
    one_shot: O,
    data: &[u8],
) -> Conformance
where
    F: Fn() -> Result<Box<DynIncrementalDecoder>, String>,
    O: Fn(&[u8]) -> Result<DecodeOutput, String>,

check_incremental_contract for any decoder factory, against one_shot, the decoder’s one-shot decode of any bytes: for incremental decoders not reached through a codec’s DecoderConfig, such as one built with zencodec::helpers::WholeFileIncremental.