benchmark: add misc/startup-cli-version benchmark

This benchmarks the startup of various CLI tools that are already
checked into the source code. We use --version because the output
tends to be minimal and fewer operations are done to generate
these so that the startup cost is still dominated by a more
indispensible part of the CLI.

benchmark/misc/startup-cli-version.js

@@ -0,0 +1,51 @@
+'use strict';
+const common = require('../common.js');
+const { spawnSync } = require('child_process');
+const path = require('path');
+
+// This benchmarks the startup of various CLI tools that are already
+// checked into the source code. We use --version because the output
+// tends to be minimal and fewer operations are done to generate
+// these so that the startup cost is still dominated by a more
+// indispensible part of the CLI.
+const bench = common.createBenchmark(main, {
+  cli: [
+    'tools/node_modules/eslint/bin/eslint.js',
+    'deps/npm/bin/npm-cli.js',
+    'deps/corepack/dist/corepack.js',
+  ],
+  count: [30],
+});
+
+function spawnProcess(cli, bench, state) {
+  const cmd = process.execPath || process.argv[0];
+  while (state.finished < state.count) {
+    const child = spawnSync(cmd, [cli, '--version'], {
+      env: { npm_config_loglevel: 'silent', ...process.env },
+    });
+    // Log some information for debugging if it fails, which it shouldn't.
+    if (child.status !== 0) {
+      console.log('---- STDOUT ----');
+      console.log(child.stdout.toString());
+      console.log('---- STDERR ----');
+      console.log(child.stderr.toString());
+      throw new Error(`Child process stopped with exit code ${child.status}`);
+    }
+    state.finished++;
+    if (state.finished === 0) {
+      // Finished warmup.
+      bench.start();
+    }
+
+    if (state.finished === state.count) {
+      bench.end(state.count);
+    }
+  }
+}
+
+function main({ count, cli }) {
+  cli = path.resolve(__dirname, '../../', cli);
+  const warmup = 3;
+  const state = { count, finished: -warmup };
+  spawnProcess(cli, bench, state);
+}