lua: string.format width/zero-pad/hex/octal/char/precision +6 tests

lib/lua/test.sh

@@ -994,6 +994,20 @@ cat > "$TMPFILE" << 'EPOCHS'
 (epoch 1912)
 (eval "(lua-eval-ast \"return string.match(\\\"abc\\\", \\\"[^a]+\\\")\")")
 
+;; ── string.format width/precision/hex/octal/char ─────────────
+(epoch 1920)
+(eval "(lua-eval-ast \"return string.format('%5d', 42)\")")
+(epoch 1921)
+(eval "(lua-eval-ast \"return string.format('%05d', 42)\")")
+(epoch 1922)
+(eval "(lua-eval-ast \"return string.format('%x', 255)\")")
+(epoch 1923)
+(eval "(lua-eval-ast \"return string.format('%X', 255)\")")
+(epoch 1924)
+(eval "(lua-eval-ast \"return string.format('%c', 65)\")")
+(epoch 1925)
+(eval "(lua-eval-ast \"return string.format('%.3s', 'hello')\")")
+
 EPOCHS
 
 OUTPUT=$(timeout 60 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
@@ -1508,6 +1522,14 @@ check 1910 "[a-z]+ on hello123"             '"hello"'
 check 1911 "[0-9]+ on hello123"             '"123"'
 check 1912 "[^a]+ on abc"                   '"bc"'
 
+# ── string.format width/precision/hex/octal/char ────────────
+check 1920 "%5d width"                      '"   42"'
+check 1921 "%05d zero-pad"                  '"00042"'
+check 1922 "%x hex"                         '"ff"'
+check 1923 "%X HEX"                         '"FF"'
+check 1924 "%c char"                        '"A"'
+check 1925 "%.3s precision"                 '"hel"'
+
 TOTAL=$((PASS + FAIL))
 if [ $FAIL -eq 0 ]; then
   echo "ok $PASS/$TOTAL Lua-on-SX tests passed"