Add e2e test cases

tests/assert-ssh-keys-set.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+# shellcheck disable=SC2086
+set -e
+
+assert_ssh_key_set() {
+  local var="$1"
+  local val
+  val="$(printenv "$var" || true)"
+  if [ -z "$val" ]; then
+    echo "Expected $var to be set"
+    exit 1
+  fi
+  if ! echo "$val" | head -1 | grep -q "BEGIN.*PRIVATE KEY"; then
+    echo "Expected $var to be a private key (missing BEGIN PRIVATE KEY header)"
+    exit 1
+  fi
+  echo "$var is set and looks like a private key"
+}
+
+assert_ssh_key_set "TEST_SSH_KEY"
+assert_ssh_key_set "TEST_SSH_KEY_OPENSSH"
+assert_ssh_key_set "FILE_TEST_SSH_KEY"
+assert_ssh_key_set "FILE_TEST_SSH_KEY_OPENSSH"