. "$BST_LIB"
require xz xz/present

tmp=${TMPDIR:-/tmp}/bst-xz.$$
line="the quick brown fox jumps over the lazy dog 0123456789"
i=0
while [ $i -lt 64 ]; do printf "%s\n" "$line"; i=$((i+1)); done > "$tmp.in" 2>/dev/null

# Compress via the stream form (xz -c > file), NOT the named-file form (xz file):
# on the wasm32-hwjs runtime the named-file path bails with "Function not
# implemented" -- xz post-write attribute restoration (fchmod/fchown/utimes on
# the output) is ENOSYS. The -c stream form touches no file attributes.
check     xz/compress   sh -c "xz -c '$tmp.in' > '$tmp.xz'"
# .xz magic is FD "7zXZ" 00; bytes 1-4 are the printable "7zXZ". Read them with
# dd (bs/skip/count), not head -c: busybox head has no -c byte-count option.
check_out xz/magic      "7zXZ"   sh -c "dd if='$tmp.xz' bs=1 skip=1 count=4 2>/dev/null"
# integrity self-check of the compressed stream
check     xz/test       xz -t "$tmp.xz"
# decompress round-trip recovers the original text (unxz alternative, -c)
check_out xz/roundtrip  "$line"  sh -c "unxz -c '$tmp.xz'"
# xzcat alternative decompresses too
check_out xz/xzcat      "$line"  sh -c "xzcat '$tmp.xz'"
# byte-for-byte identity of the round-trip
unxz -c "$tmp.xz" > "$tmp.out" 2>/dev/null
check     xz/identical  cmp -s "$tmp.in" "$tmp.out"

rm -f "$tmp.in" "$tmp.xz" "$tmp.out"