From 70ec69337188f15c878b7aa72338830e278bfb6f Mon Sep 17 00:00:00 2001
From: David Tanner <david.tanner@lifeomic.com>
Date: Fri, 5 May 2023 10:11:58 -0600
Subject: [PATCH] feat: Merge the provided externals list with any we want to
 add here

---
 src/bundle.test.ts |  7 +++----
 src/bundle.ts      | 38 ++++++++++++++++++++++----------------
 2 files changed, 25 insertions(+), 20 deletions(-)

diff --git a/src/bundle.test.ts b/src/bundle.test.ts
index f5daf59..340f18b 100644
--- a/src/bundle.test.ts
+++ b/src/bundle.test.ts
@@ -258,7 +258,7 @@ describe('AWS SDK bundling behavior', () => {
     await bundle({
       entries: `${TEST_INPUT_DIR}/first-file.js`,
       outdir: TEST_OUTPUT_DIR,
-      node: 15,
+      node: 16,
       includeAwsSdk: true,
     });
 
@@ -268,7 +268,7 @@ describe('AWS SDK bundling behavior', () => {
         bundle: true,
         sourcemap: false,
         platform: 'node',
-        target: 'node15',
+        target: 'node16',
         external: [],
         resolveExtensions: ['.jsx', '.js', '.tsx', '.ts', '.json'],
       }),
@@ -309,9 +309,8 @@ describe('AWS SDK bundling behavior', () => {
    *
    * We'll use these assumptions to make assertions below.
    */
-
   // Node 12, 14, 16 behavior
-  [12, 14, 16].forEach((node) => {
+  describe.each([12, 14, 16])('Node %#', (node) => {
     test(`does not bundle aws-sdk in node version ${node}`, async () => {
       const output = await bundleCode({
         node,
diff --git a/src/bundle.ts b/src/bundle.ts
index 5e7f1c1..dfac6fb 100644
--- a/src/bundle.ts
+++ b/src/bundle.ts
@@ -6,7 +6,7 @@ import { promises as fs } from 'fs';
 
 export type BundleOptions = {
   /**
-   * The entrypoint (or entrypoints) to bundle. This can be a glob pattern matching
+   * The entrypoint/s to bundle. This can be a glob pattern matching
    * multiple source files (or a list of glob patterns).
    */
   entries: string | string[];
@@ -38,18 +38,37 @@ export type BundleOptions = {
   esbuild?: ESBuildOptions;
 };
 
+const addIfMissing = (arr: string[], str: string) => {
+  if (!arr.includes(str)) {
+    arr.push(str);
+  }
+};
+
 export const bundle = async ({
   entries,
   outdir,
   node: nodeVersion,
   cwd,
   includeAwsSdk = false,
-  esbuild,
+  esbuild: { external = [], ...esbuild } = {},
 }: BundleOptions) => {
   const entryPoints = (typeof entries === 'string' ? [entries] : entries)
     .map((pattern) => glob.sync(pattern, cwd ? { cwd } : undefined))
     .flat();
 
+  if (!includeAwsSdk) {
+    /**
+     * Don't bundle the AWS SDK, since it is natively available
+     * in the Lambda environment.
+     *
+     * Node runtimes < 18 include the v2 sdk, while runtimes >= 18 include
+     * the v3 SDK.
+     *
+     * https://aws.amazon.com/blogs/compute/node-js-18-x-runtime-now-available-in-aws-lambda/
+     */
+    addIfMissing(external, nodeVersion >= 18 ? '@aws-sdk/*' : 'aws-sdk');
+  }
+
   const buildResult = await withTiming(() =>
     build({
       bundle: true,
@@ -58,20 +77,7 @@ export const bundle = async ({
       target: `node${nodeVersion}`,
       outdir,
       entryPoints,
-      /**
-       * Don't bundle the AWS SDK, since it is natively available
-       * in the Lambda environment.
-       *
-       * Node runtimes < 18 include the v2 sdk, while runtimes >= 18 include
-       * the v3 SDK.
-       *
-       * https://aws.amazon.com/blogs/compute/node-js-18-x-runtime-now-available-in-aws-lambda/
-       */
-      external: includeAwsSdk
-        ? []
-        : nodeVersion >= 18
-        ? ['@aws-sdk/*']
-        : ['aws-sdk'],
+      external,
       /**
        * As of v0.14.44, esbuild by default prefers .ts over .js files.
        *