test: set up kokoro job for sdk schema test

PiperOrigin-RevId: 662674058

.kokoro/presubmit/node18/sdk-schema-test.cfg

@@ -0,0 +1,5 @@
+# Download resources for system tests (service account key, etc.)
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/nodejs-vertexai/.kokoro/sdk-schema-test.sh"
+}

.kokoro/sdk-schema-test.sh

@@ -0,0 +1,58 @@
+#!/bin/bash
+
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -e
+
+export TEST_REPO=nodejs-vertexai
+CURRENT_VERSION=$(node -v 2>/dev/null || echo "none")
+REQUIRED_VERSION="v18.0.0"
+
+install_node() {
+  echo "Installing Node.js via NodeSource..."
+  curl -fsSL https://deb.nodesource.com/setup_18.x | sudo -E bash -
+  sudo apt-get install -y nodejs
+}
+
+compare_versions() {
+  [ "$(printf '%s\n' "$1" "$2" | sort -V | head -n1)" != "$1" ]
+}
+
+if [ "$CURRENT_VERSION" = "none" ]; then
+  echo "Node.js is not installed. Installing Node.js..."
+  install_node
+else
+  echo "Current Node.js version: $CURRENT_VERSION"
+
+  if compare_versions "$CURRENT_VERSION" "$REQUIRED_VERSION"; then
+    echo "Node.js version is greater than or equal to $REQUIRED_VERSION"
+  else
+    echo "Node.js version is less than $REQUIRED_VERSION. Installing the required version..."
+    install_node
+  fi
+fi
+
+echo "Node.js installation or upgrade process completed."
+
+npm install
+git clone https://github.com/google-gemini/generative-ai-js.git
+sudo npm install -g ts-node && sudo npm install -g typescript
+ts-node sdk_schema_test/vertex_ai/*test.ts
+ts-node sdk_schema_test/google_ai/*test.ts
+rm -rf generative-ai-js
+rm -rf build
+rm -rf node_modules
+find . -type f -name "*.js" ! -path "./test/spec/*" ! -name ".*.js" -exec rm {} \;
+rm package-lock.json