test(scripts): add npm start script test

tests/start-script.test.js

@@ -0,0 +1,10 @@
+const { spawnSync } = require('child_process');
+
+describe('NPM Start Script', () => {
+  test('npm start exits without error when DISCORD_TOKEN is provided', () => {
+    const env = { ...process.env, DISCORD_TOKEN: 'dummy-token', CLIENT_ID: '123', LAVALINK_HOST: 'localhost', LAVALINK_PORT: '2333', LAVALINK_PASSWORD: 'pass' };
+    const result = spawnSync('pnpm', ['start'], { env, encoding: 'utf-8' });
+    // The script starts the bot; if it reaches login attempt, exit code is 0
+    expect(result.status).toBe(0);
+  });
+});