Add basic metadata analysis script

Author: mbg

package.json

@@ -5,7 +5,7 @@
   "description": "CodeQL action",
   "scripts": {
     "_build_comment": "echo 'Run the full build so we typecheck the project and can reuse the transpiled files in npm test'",
-    "build": "./scripts/check-node-modules.sh && npm run transpile && node build.mjs",
+    "build": "./scripts/check-node-modules.sh && npm run transpile && node build.mjs && npx tsx ./pr-checks/bundle-metadata.ts",
     "lint": "eslint --report-unused-disable-directives --max-warnings=0 .",
     "lint-ci": "SARIF_ESLINT_IGNORE_SUPPRESSED=true eslint --report-unused-disable-directives --max-warnings=0 . --format @microsoft/eslint-formatter-sarif --output-file=eslint.sarif",
     "lint-fix": "eslint --report-unused-disable-directives --max-warnings=0 . --fix",

pr-checks/bundle-metadata.ts

@@ -0,0 +1,31 @@
+#!/usr/bin/env npx tsx
+
+import * as fs from "node:fs/promises";
+
+import { BUNDLE_METADATA_FILE } from "./config";
+
+interface Output {
+  bytes: number;
+}
+
+interface Metadata {
+  outputs: Output[];
+}
+
+async function main() {
+  const fileContents = await fs.readFile(BUNDLE_METADATA_FILE);
+  const metadata = JSON.parse(String(fileContents)) as Metadata;
+
+  for (const [outputFile, outputData] of Object.entries(
+    metadata.outputs,
+  ).reverse()) {
+    console.info(
+      `${outputFile}: ${(outputData.bytes / (1024 * 1024)).toFixed(2)}MB`,
+    );
+  }
+}
+
+// Only call `main` if this script was run directly.
+if (require.main === module) {
+  void main();
+}

pr-checks/config.ts

@@ -8,3 +8,6 @@ export const PR_CHECKS_DIR = __dirname;
 
 /** The path of the file configuring which checks shouldn't be required. */
 export const PR_CHECK_EXCLUDED_FILE = path.join(PR_CHECKS_DIR, "excluded.yml");
+
+/** The path to the esbuild metadata file. */
+export const BUNDLE_METADATA_FILE = path.join(PR_CHECKS_DIR, "..", "meta.json");