During a widget test, I want to write to the dev environment file system, instead of writing to the device’s file system. (So, using dart.io instead of path_provider.)

For reason’s I don’t understand, the writeAsString function hangs. E.g., here’s a minimal example where execution hangs on the writeAsString call and never reaches the debugPrint line. The TestFile.txt is created within the local test directory, but it is empty.

import 'dart:io';
import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  testWidgets('Try writing to dev system within test', (WidgetTester tester) async {
    await tester.pumpWidget(const SizedBox.shrink());
    await tester.pumpAndSettle();

    final file = File('TestFile.txt');
    await file.writeAsString('Some Text');
    debugPrint('Test completed');
  });
}