void enableFlutterDriverExtension()

Enables Flutter Driver VM service extension.

This extension is required for tests that use package:flutter_driver to drive applications from a separate process.

Call this function prior to running your application, e.g. before you call runApp.

Source 

void enableFlutterDriverExtension() {
  assert(WidgetsBinding.instance == null);
  new _DriverBinding();
  assert(WidgetsBinding.instance is _DriverBinding);
}