Add documentation and tests

Author: Tj

doc/api/cli.md

@@ -3454,6 +3454,7 @@ V8 options that are allowed are:
 * `--expose-gc`
 * `--interpreted-frames-native-stack`
 * `--jitless`
+* `--max-heap-size`
 * `--max-old-space-size`
 * `--max-semi-space-size`
 * `--perf-basic-prof-only-functions`

test/common/v8-max-heap-size-option.js

@@ -0,0 +1,41 @@
+'use strict';
+
+const assert = require('assert');
+const { spawnSync } = require('child_process');
+const path = require('path');
+const fs = require('fs');
+const tmpdir = require('./tmpdir');
+
+const testScript = `
+  const v8 = require('v8');
+  const stats = v8.getHeapStatistics();
+  const maxHeapSizeMB = Math.round(stats.heap_size_limit / 1024 / 1024);
+  console.log(maxHeapSizeMB);
+`;
+
+tmpdir.refresh();
+const scriptPath = path.join(tmpdir.path, 'heap-limit-test.js');
+fs.writeFileSync(scriptPath, testScript);
+
+const child = spawnSync(
+  process.execPath,
+  [scriptPath],
+  {
+    encoding: 'utf8',
+    env: {
+      ...process.env,
+      NODE_OPTIONS: '--max-heap-size=750'
+    }
+  }
+);
+
+assert.strictEqual(child.status, 0, 'Child process did not exit cleanly');
+const output = child.stdout.trim();
+const heapLimit = Number(output);
+
+assert.strictEqual(
+  heapLimit,
+  750,
+  `max heap size is ${heapLimit}MB, expected 750MB`
+);
+