benchmark: create rotating hex benchmark

Author: araujogui

benchmark/util/style-text.js

@@ -5,9 +5,22 @@ const common = require('../common.js');
 const { styleText } = require('node:util');
 const assert = require('node:assert');
 
+// 1000 distinct hex colors to exercise the cache under high-miss conditions.
+// Spread evenly across hue space so colors are valid and maximally varied.
+const kHexColorCount = 1000;
+const toHex = (n) => n.toString(16).padStart(2, '0');
+const hexColors = Array.from({ length: kHexColorCount }, (_, i) => {
+  const r = (i * 37) & 0xff;
+  const g = (i * 73) & 0xff;
+  const b = (i * 137) & 0xff;
+  return `#${toHex(r)}${toHex(g)}${toHex(b)}`;
+});
+
 const bench = common.createBenchmark(main, {
   messageType: ['string', 'number', 'boolean', 'invalid'],
-  format: ['red', 'italic', 'invalid', '#ff0000'],
+  // '#rotating' cycles through kHexColorCount distinct colors to simulate
+  // the high-miss-rate / large-cache scenario (e.g. user-randomised colors).
+  format: ['red', 'italic', 'invalid', '#ff0000', '#rotating'],
   validateStream: [1, 0],
   n: [1e3],
 });
@@ -31,9 +44,10 @@ function main({ messageType, format, validateStream, n }) {
 
   bench.start();
   for (let i = 0; i < n; i++) {
+    const fmt = format === '#rotating' ? hexColors[i % kHexColorCount] : format;
     let colored = '';
     try {
-      colored = styleText(format, str, { validateStream });
+      colored = styleText(fmt, str, { validateStream });
       assert.ok(colored); // Attempt to avoid dead-code elimination
     } catch {
       // eslint-disable no-empty