Flutter unit test failed

Question

I was trying to do a unit test in Flutter.

In pubspec.yaml the dependency is included:

test: any

Running flutter analyze shows no warnings.

Created a unit_test.dart under test folder in my project:

import 'package:test/test.dart';

void main()
{
    test('this is a test', (){
        expect(42, equals(42));
        //expect(42,42);
    });
}

Running flutter test shows me the following error:

➜  HelloFlutter flutter test test/unit_test.dart
00:00 +0: loading /home/tr/programs/HelloFlutter/test/unit_test.dart            00:00 +0 -1: loading /home/tr/programs/HelloFlutter/test/unit_test.dart         00:00 +0 -1: loading /home/tr/programs/HelloFlutter/test/unit_test.dart                            
  Failed to load "/home/tr/programs/HelloFlutter/test/unit_test.dart": Failed assertion: boolean expression must not be null
  package:test              test
  test/unit_test.dart 6:2   main
  dart:async                _StreamController.add
  websocket_impl.dart 1111  _WebSocketImpl._WebSocketImpl._fromSocket.<fn>
  dart:async                _EventSinkWrapper.add
  websocket_impl.dart 333   _WebSocketProtocolTransformer._messageFrameEnd
  websocket_impl.dart 228   _WebSocketProtocolTransformer.add

00:00 +0 -1: Some tests failed.     

Any hint?

Solution

The actual test you posted looks like a regular "test" test, as opposed to a "flutter_test" test. So you probably just want to run it using regular dart rather than via flutter's test harness.

The diagnostics we give in these situations are horrific. That's being tracked at: https://github.com/flutter/flutter/issues/6187

Comments

[TaylorR]

Tried the above method, when running flutter packages get, it gets these errors: Incompatible dependencies on flutter... pub get failed

[Alexandre Ardhuin]

It works on my project. Could you post your pubspec.yaml ?

[Günter Zöchbauer]

I also tried it in my flutter project and this fixed it for me.

[TaylorR]

The pubspec.yaml is the default one created by flutter create. Added the lines above per Alex's input only.

[Alexandre Ardhuin]

Really strange because I did flutter create, created a file test/my_test.dart with your test content and ran flutter test to see the same error you faced. After putting only the dependency mention in my answer the error went away and the test was run.

[TaylorR]

Let me try later today and revert.

[Ian Hickson]

Oh man, that explains why I keep seeing people do expects(42, 42) !

[TaylorR]

Tried again today and seems working with Alex's method.