test: add trace-gc flag test

PR-URL: #42471
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>

test/fixtures/gc.js

@@ -0,0 +1,9 @@
+let arr = new Array(300_000).fill('a');
+
+for (let index = 0; index < arr.length; index++) {
+  arr[index] = Math.random();
+}
+
+arr = [];
+// .gc() is called to generate a Mark-sweep event
+global.gc();

test/v8-updates/test-trace-gc-flag.js

@@ -0,0 +1,40 @@
+'use strict';
+
+// This test verifies that `--trace-gc` flag is well integrated.
+// We'll check here, that the console outputs gc events properly.
+require('../common');
+
+const assert = require('assert');
+const { spawnSync } = require('child_process');
+
+const fixtures = require('../common/fixtures');
+
+{
+  const childProcess = spawnSync(process.execPath, [
+    '--trace-gc',
+    '--expose-gc',
+    fixtures.path('gc.js'),
+  ]);
+  const output = childProcess.stdout.toString().trim();
+  const lines = splitByLine(output);
+
+  const scavengeRegex = /\bScavenge\b/;
+  const expectedOutput = [
+    scavengeRegex,
+    scavengeRegex,
+    scavengeRegex,
+    scavengeRegex,
+    /\bMark-sweep\b/,
+  ];
+  lines.forEach((line, index) => {
+    assert.match(line, expectedOutput[index]);
+  });
+}
+
+/**
+ * HELPERS
+ */
+
+function splitByLine(str) {
+  return str.split(/\n/);
+}