tests: add preflight TLS script

tests/preflight-tls.sh

@@ -0,0 +1,21 @@
+#!/bin/sh
+
+set -e -u
+
+genectls() {
+  openssl ecparam -genkey -name "${1}" -out "${2}.key"
+  openssl req -new -sha256 -subj "/CN=${1}" -key "${2}.key" -out "${2}.csr"
+  openssl req -x509 -sha256 -days 365 -key "${2}.key" -in "${2}.csr" -out "${2}.crt"
+}
+
+PFX="${NODEMCU_TESTTMP}/tmp-ec256v1"
+[ -r "${PFX}.key" ] || genectls "prime256v1" "${PFX}"
+
+PFX="${NODEMCU_TESTTMP}/tmp-ec384r1"
+[ -r "${PFX}.key" ] || genectls "secp384r1" "${PFX}"
+
+PFX="${NODEMCU_TESTTMP}/tmp-rsa2048"
+[ -r "${PFX}.key" ] || {
+  openssl genrsa -out "${PFX}.key" "2048"
+  openssl req -x509 -nodes -subj "/CN=rsa" -key "${PFX}.key" -out "${PFX}.crt" "-days" "365"
+}