title: How to solve Not found: 'dart:ui' error while running integration tests on Flutter
body: <p>I have an app, it is very simple and have just one widget. It is working fine, however when I run integration test by calling:</p>
  
  <pre><code>$ flutter drive --target=test_driver/app.dart 
  </code></pre>
  
  <p>I get the following error:</p>
  
  <pre><code> file:///Users/myuser/flutter/packages/flutter_test/lib/src/accessibility.dart:8:8: Error: Not found: 'dart:ui'
  import 'dart:ui' as ui;
         ^
  file:///Users/myuser/flutter/packages/flutter_test/lib/src/binding.dart:8:8: Error: Not found: 'dart:ui'
  import 'dart:ui' as ui;
         ^
  file:///Users/myuser/flutter/packages/flutter_test/lib/src/matchers.dart:8:8: Error: Not found: 'dart:ui'
  import 'dart:ui' as ui;
         ^
  file:///Users/myuser/flutter/packages/flutter_test/lib/src/matchers.dart:9:8: Error: Not found: 'dart:ui'
  import 'dart:ui';
         ^
  file:///Users/myuser/flutter/packages/flutter_test/lib/src/test_pointer.dart:12:1: Error: Not found: 'dart:ui'
  export 'dart:ui' show Offset;
  ^
  file:///Users/myuser/flutter/packages/flutter/lib/src/rendering/binding.dart:8:8: Error: Not found: 'dart:ui'
  import 'dart:ui' as ui show window;
         ^
  file:///Users/myuser/flutter/packages/flutter/lib/src/rendering/box.dart:6:8: Error: Not found: 'dart:ui'
  import 'dart:ui' as ui show lerpDouble;
         ^
  file:///Users/myuser/flutter/packages/flutter/lib/src/rendering/debug_overflow_indicator.dart:6:8: Error: Not found: 'dart:ui'
  import 'dart:ui' as ui;
         ^
  file:///Users/myuser/flutter/packages/flutter/lib/src/rendering/editable.dart:8:8: Error: Not found: 'dart:ui'
  import 'dart:ui' as ui show TextBox;
         ^
  file:///Users/myuser/flutter/packages/flutter/lib/src/rendering/error.dart:5:8: Error: Not found: 'dart:ui'
  import 'dart:ui' as ui show Paragraph, ParagraphBuilder, ParagraphConstraints, ParagraphStyle, TextStyle;
         ^
  Stopping application instance.
  Driver tests failed: 254
  </code></pre>
  
  <p>Note that when I run the app from Android Studio, it runs successfully. But when I run from terminal using the command quoted above, the app shows a white screen and it doesn't move from there until I get the error on my terminal.</p>
  
  <p>Assuming it's a path issue, like test_driver not finding flutter packages like dart:ui, how can I make sure test_driver knows where dart:ui is ?</p>