function testIntegrationFile(callback) {
	const server = startServer(serverOptions, error => {
		if (error) {
			return callback(error);
		}
		execFile('node',
			[join('./', 'bin', 'loadtest.js'), `http://localhost:${port}/`,
				'-n', '100', '--quiet'],
			(error, stdout) => {
				if (error) {
					return callback(error);
				}
				server.close(error => {
					if (error) {
						return callback(error);
					}
					return callback(null, 'Test result: ' + stdout);
				});
			});
	});
}
Run an integration test using configuration file.