Unit testing with dart's shelf_rest

I'm trying to test a Dart REST app run on shelf_rest. Assuming a setup similar to the shelf_rest example, how can one test the configured routes without actually running an HTTP server?

import 'package:shelf/shelf.dart';
import 'package:shelf/shelf_io.dart' as io;
import 'package:shelf_rest/shelf_rest.dart';

void main() {
  var myRouter = router()
    ..get('/accounts/{accountId}', (Request request) {
      var account = new Account.build(accountId: getPathParameter(request, 'accountId'));
      return new Response.ok(JSON.encode(account));
    });

  io.serve(myRouter.handler, 'localhost', 8080);
}

class Account {
  final String accountId;

  Account.build({this.accountId});

  Account.fromJson(Map json) : this.accountId = json['accountId'];

  Map toJson() => {'accountId': accountId};
}  

class AccountResource {
  @Get('{accountId}')
  Account find(String accountId) => new Account.build(accountId: accountId);
}

Without getting into too much additional logic, how could the GET account endpoint be unit tested? Some basic tests I'd like to run would be:

• GET /accounts/123 returns 200
• GET /accounts/bogus returns 404

To create a unit test (i.e. without a running server) then you need to split myRouter outside of the main function and put it in a file in the lib dir. e.g

import 'dart:convert';

import 'package:shelf/shelf.dart';
import 'package:shelf_rest/shelf_rest.dart';

var myRouter = router()
  ..get('/accounts/{accountId}', (Request request) {
    var account =
        new Account.build(accountId: getPathParameter(request, 'accountId'));
    return new Response.ok(JSON.encode(account));
  });

class Account {
  final String accountId;

  Account.build({this.accountId});

  Account.fromJson(Map json) : this.accountId = json['accountId'];

  Map toJson() => {'accountId': accountId};
}

Then create a test file in the test directory and test like

import 'package:soQshelf_rest/my_router.dart';
import 'package:test/test.dart';
import 'package:shelf/shelf.dart';
import 'dart:convert';

main() {
  test('/account/{accountId} should return expected response', () async {
    final Handler handler = myRouter.handler;
    final Response response = await handler(
        new Request('GET', Uri.parse('http://localhost:9999/accounts/123')));
    expect(response.statusCode, equals(200));
    expect(JSON.decode(await response.readAsString()),
        equals({"accountId": "123"}));
  });
}