Encoder.ReadFrom() (added in v4) is buggy about lz4 HOT 2 CLOSED

package main

import (
	"bytes"
	"encoding/hex"
	"fmt"
	"io"
	"os"
	"testing"

	lzv3 "github.com/pierrec/lz4/v3"
	lzv4 "github.com/pierrec/lz4/v4"
)

type Generator func(io.WriteCloser) io.WriteCloser

func TestFoo(t *testing.T) {
	for i, gen := range []Generator{initV3, initV4} {
		fmt.Printf("\n===Generator %d, piecemeal===\n", i)
		dumper := hex.Dumper(os.Stdout)
		coder := gen(dumper)
		for _, v := range inStream {
			n, err := io.CopyN(coder, bytes.NewReader(v), int64(len(v)))
			if n != int64(len(v)) || err != nil {
				fmt.Printf("Failed to write %v\n", err)
			}
		}
		coder.Close()
		dumper.Close()

		fmt.Printf("\n===Generator %d, clean buffered===\n", i)
		var allAtOnce bytes.Buffer
		for _, v := range inStream {
			n, err := io.CopyN(&allAtOnce, bytes.NewReader(v), int64(len(v)))
			if n != int64(len(v)) || err != nil {
				fmt.Printf("Failed to write: %v\n", err)
				break
			}
		}

		dumper2 := hex.Dumper(os.Stdout)
		coder2 := gen(dumper2)
		io.Copy(coder2, bytes.NewReader(allAtOnce.Bytes()))
		coder2.Close()
		dumper2.Close()
	}
	fmt.Println()
}

func initV3(out io.WriteCloser) io.WriteCloser {
	lz4Writer := lzv3.NewWriter(out)
	return lz4Writer
}

func initV4(out io.WriteCloser) io.WriteCloser {
	lz4Writer := lzv4.NewWriter(out)
	return lz4Writer
}

var inStream = [][]byte{
	{5, 0, 4, 0, 0, 0, 116, 104, 105, 115, 2, 0, 0, 0, 105, 115, 1, 0, 0, 0, 97, 4, 0, 0, 0, 116, 101, 115, 116, 8, 0, 0, 0, 112, 114, 111, 98, 97, 98, 108, 121},
	{1, 0, 0, 0, 13, 0, 0, 0},
	{255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 15},
}