Implement iptables forward manager core

tests/lib/assert.sh

@@ -0,0 +1,54 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+fail() {
+  printf 'ASSERT FAIL: %s\n' "$*" >&2
+  exit 1
+}
+
+pass() {
+  printf 'ASSERT PASS: %s\n' "$*"
+}
+
+assert_eq() {
+  local expected=$1
+  local actual=$2
+  local message=${3:-values differ}
+  [[ ${expected} == "${actual}" ]] || fail "${message} (expected='${expected}' actual='${actual}')"
+}
+
+assert_ne() {
+  local left=$1
+  local right=$2
+  local message=${3:-values should differ}
+  [[ ${left} != "${right}" ]] || fail "${message} (value='${left}')"
+}
+
+assert_contains() {
+  local haystack=$1
+  local needle=$2
+  local message=${3:-substring not found}
+  [[ ${haystack} == *"${needle}"* ]] || fail "${message} (needle='${needle}')"
+}
+
+assert_not_contains() {
+  local haystack=$1
+  local needle=$2
+  local message=${3:-unexpected substring found}
+  [[ ${haystack} != *"${needle}"* ]] || fail "${message} (needle='${needle}')"
+}
+
+assert_file_contains() {
+  local file=$1
+  local needle=$2
+  local message=${3:-file does not contain substring}
+  [[ -f ${file} ]] || fail "file not found: ${file}"
+  grep -Fq -- "${needle}" "${file}" || fail "${message} (file='${file}' needle='${needle}')"
+}
+
+assert_status() {
+  local expected=$1
+  local actual=$2
+  local message=${3:-unexpected exit status}
+  [[ ${expected} == "${actual}" ]] || fail "${message} (expected=${expected} actual=${actual})"
+}