My Flutter app has a test folder test. Inside is another folder called fixtures.

Here is the fixture_reader.dart file:

import 'dart:io';

String fixture(String name) => File('test/fixtures/$name').readAsStringSync();

Now I can use the function to read a fixture in a test:

// code ommitted
  group('fromJson', () {
    test(
      'should return a valid model when the JSON number is an integer',
      () async {
        // arrange
        final Map<String, dynamic> jsonMap =
            json.decode(fixture('trivia.json'));
            // more code

Problem

Now run flutter test in the command line.

Unfortunately, that gives an error, although all imports are correct:

FileSystemException: Cannot open file, path = 'test/fixtures/trivia.json'
(OS Error: No such file or directory, errno = 2)
 dart:io  File.readAsStringSync 
fixtures/fixture_reader.dart 3:60                                       fixture
features/number_trivia/data/models/number_trivia_model_test.dart 26:25  main.<fn>.<fn

Why do I have these errors, although the files exist?
FileSystemException: Cannot open file
(OS Error: No such file or directory, errno = 2)

It seems like flutter test can’t find the file paths! If you use VS Code, the test works fine. But if you use CI/CD, the test will fail.

Solution

Replace file_reader.dart:

import 'dart:io';

String fixture(String name) {
   var dir = Directory.current.path;
   if (dir.endsWith('/test')) {
     dir = dir.replaceAll('/test', '');
   }
   return File('$dir/test/fixtures/$name').readAsStringSync();
}

Resources