MemoryDirectory does not list files properly on Windows

[renatoathaydes]

I'm using the MemoryFileSystem in some of my tests, and they fail only on Windows. I tracked down the cause of the failure to this minimal test of MemoryDirectory:

import 'package:file/memory.dart';
import 'package:path/path.dart';
import 'package:test/test.dart';

void main([List<String> args = const []]) {
  group('MemoryFileSystem', () {
    var fs = MemoryFileSystem();

    setUp(() async {
      fs = MemoryFileSystem();
    });

    test('can list files inside a directory', () async {
      final dir = fs.directory('d');
      await dir.create();
      final foo = fs.file(join('d', 'foo'));
      await foo.writeAsString('foo');
      final bar = fs.file(join('d', 'bar'));
      await bar.writeAsString('bar');
      expect(dir.list().map((f) => f.basename),
          emitsInAnyOrder(['foo', 'bar', emitsDone]));
    });
  });
}

The failure on Windows only (it passes on Mac and Linux):

00:18 +26 -6: test\files_test.dart: MemoryFileSystem can list files inside a directory [E]
  Expected: should do the following in any order:
            * emit an event that 'foo'
            * emit an event that 'bar'
            * be done
    Actual: <Instance of '_MapStream<FileSystemEntity, String>'>
     Which: emitted x Stream closed.
  
  package:test_api           expect
  test\files_test.dart 70:7  main.<fn>.<fn>
  ===== asynchronous gap ===========================
  dart:async                 _asyncThenWrapperHelper
  test\files_test.dart       main.<fn>.<fn>

You can see the actual test logs of my project where I added this test, on the GitHub Actions Log.