Function async_codec_util::testing::test_codec_len

pub fn test_codec_len<R: AsyncRead, W: AsyncWrite, D: AsyncDecode, C: AsyncEncodeLen>(
    reader: R, 
    writer: W, 
    dec: D, 
    co: C
) -> (D::Item, bool) where
    D::Error: Debug, 

Run an encoder and a decoder concurrently, returning the decoded output and whether the encoder produced as many bytes as it promised and as the decoder consumed.