testing dart code in android studio (no widgets involved, only data structures and concepts)

Question

I want to run this code in android studio. I got the entire file from this webpage: https://flutter.dev/docs/cookbook/persistence/sqlite. I already have the pubspec.yaml packages already set up, but im getting errors. Here's the widget_test.dart file that came by default. I commented out the await tester.pumpWidget(myApp()); because myApp() is no longer defined.

import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';

import 'package:sqlite_example/main.dart';

void main() {
  testWidgets('Counter increments smoke test', (WidgetTester tester) async {
    // Build our app and trigger a frame.
//    await tester.pumpWidget(myApp());

    // Verify that our counter starts at 0.
    expect(find.text('0'), findsOneWidget);
    expect(find.text('1'), findsNothing);

    // Tap the '+' icon and trigger a frame.
    await tester.tap(find.byIcon(Icons.add));
    await tester.pump();

    // Verify that our counter has incremented.
    expect(find.text('0'), findsNothing);
    expect(find.text('1'), findsOneWidget);
  });
}

error message:

Testing started at 23:12 ...
/Users/leozhang/flutter/bin/flutter --no-color test --machine test/widget_test.dart
══╡ EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ╞════════════════════════════════════════════════════
The following TestFailure object was thrown running a test:
  Expected: exactly one matching node in the widget tree
  Actual: _TextFinder:<zero widgets with text "0" (ignoring offstage widgets)>
   Which: means none were found but one was expected

When the exception was thrown, this was the stack:
#4      main.<anonymous closure> (file:///Users/leozhang/Desktop/DesktopStuff/flutter_playground_files/sqlite_example/test/widget_test.dart:19:5)
#5      testWidgets.<anonymous closure>.<anonymous closure> (package:flutter_test/src/widget_tester.dart:124:25)
#6      TestWidgetsFlutterBinding._runTestBody (package:flutter_test/src/binding.dart:696:19)
<asynchronous suspension>
#9      TestWidgetsFlutterBinding._runTest (package:flutter_test/src/binding.dart:679:14)
#10     AutomatedTestWidgetsFlutterBinding.runTest.<anonymous closure> (package:flutter_test/src/binding.dart:1050:24)
#16     AutomatedTestWidgetsFlutterBinding.runTest (package:flutter_test/src/binding.dart:1047:15)
#17     testWidgets.<anonymous closure> (package:flutter_test/src/widget_tester.dart:121:22)
#18     Declarer.test.<anonymous closure>.<anonymous closure>.<anonymous closure> (package:test_api/src/backend/declarer.dart:171:27)
<asynchronous suspension>
#19     Invoker.waitForOutstandingCallbacks.<anonymous closure> (package:test_api/src/backend/invoker.dart:242:15)
#24     Invoker.waitForOutstandingCallbacks (package:test_api/src/backend/invoker.dart:239:5)
#25     Declarer.test.<anonymous closure>.<anonymous closure> (package:test_api/src/backend/declarer.dart:169:33)
#30     Declarer.test.<anonymous closure> (package:test_api/src/backend/declarer.dart:168:13)
#31     Invoker._onRun.<anonymous closure>.<anonymous closure>.<anonymous closure>.<anonymous closure> (package:test_api/src/backend/invoker.dart:392:25)
#45     _Timer._runTimers (dart:isolate-patch/timer_impl.dart:384:19)
#46     _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:418:5)
#47     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:174:12)
(elided 28 frames from class _FakeAsync, package dart:async, package dart:async-patch, and package stack_trace)

This was caught by the test expectation on the following line:
  file:///Users/leozhang/Desktop/DesktopStuff/flutter_playground_files/sqlite_example/test/widget_test.dart line 19
The test description was:
  Counter increments smoke test
════════════════════════════════════════════════════════════════════════════════════════════════════

Test failed. See exception logs above.
The test description was: Counter increments smoke test

my main.dart just has the entire code from the website I mentioned earlier. Thanks for reading!

Answer 1

The issue here is that you're running Widget tests with testWidgets() function. To run tests without widgets, you can run unit tests using test() function as demonstrated on this guide.