Add test harness: setup lib, dev mode, automated test runner

test/dev.mjs

@@ -0,0 +1,43 @@
+#!/usr/bin/env node
+// Developer mode: set up loop device, stream fa2json output through jq,
+// tear down on exit. Optionally launch a terminal at the mount point.
+//
+// Usage:
+//   sudo node test/dev.mjs
+//   sudo node test/dev.mjs --terminal konsole
+//   sudo node test/dev.mjs --terminal "konsole -e bash"
+
+import { spawn } from 'node:child_process';
+import { createInterface } from 'node:readline';
+import { setup, spawnFa2json } from './lib/setup.mjs';
+
+const terminalArg = (() => {
+	const i = process.argv.indexOf('--terminal');
+	return i !== -1 ? process.argv.slice(i + 1).join(' ') : null;
+})();
+
+const { mnt, teardown } = await setup();
+console.error(`Mount point: ${mnt}`);
+
+// Pipe fa2json stdout through jq for pretty coloured output
+const fa2json = spawnFa2json(mnt);
+const jq = spawn('jq', ['-C', '--unbuffered', '.'], { stdio: ['pipe', 'inherit', 'inherit'] });
+fa2json.stdout.pipe(jq.stdin);
+
+fa2json.on('exit', async () => {
+	jq.stdin.end();
+	await teardown();
+	process.exit(0);
+});
+
+// Launch optional terminal at mount point
+if (terminalArg) {
+	const [cmd, ...args] = terminalArg.split(' ');
+	spawn(cmd, [...args, '--workdir', mnt], { detached: true, stdio: 'ignore' }).unref();
+	console.error(`Launched: ${terminalArg} --workdir ${mnt}`);
+}
+
+// Clean teardown on Ctrl+C
+process.on('SIGINT', async () => {
+	fa2json.kill('SIGTERM');
+});