fix/pending-timer

[nank1ro]

Hi,

I'm opening a PR to fix a bug I have on shadcn_ui, related issue nank1ro/flutter-shadcn-ui#294

The problem is that ShadApp uses ShadToaster which uses Animate from your package.
When the user runs tests with it, it gets the following error

Pending timers:
Timer (duration: 0:00:00.000000, periodic: false), created:
#0      new FakeTimer._ (package:fake_async/fake_async.dart:308:62)
#1      FakeAsync._createTimer (package:fake_async/fake_async.dart:252:27)
#2      FakeAsync.run.<anonymous closure> (package:fake_async/fake_async.dart:185:19)
#6      _AnimateState._restart (package:flutter_animate/src/animate.dart:318:23)
#7      _AnimateState.initState (package:flutter_animate/src/animate.dart:290:5)

The test failing is the basic counter test:

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

import 'package:shadcn_counter/main.dart';

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

Code for main app

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

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return ShadApp.material(
      title: 'Flutter Demo',
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headlineMedium,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ),
    );
  }
}

Pubspec

dependencies:
  flutter:
    sdk: flutter
  cupertino_icons: ^1.0.8
  shadcn_ui: ^0.19.3

The ShadToaster doesn't do nothing too special, just a basic usage with controller and effects

                  return Animate(
                    controller: _controller,
                    effects: visible ? effectiveAnimateIn : effectiveAnimateOut,
                    child: Align(
                      alignment: effectiveAlignment,
                      child: Padding(
                        padding: EdgeInsets.symmetric(
                          horizontal: effectiveOffset.dx,
                          vertical: effectiveOffset.dy,
                        ),
                        child: toast,
                      ),
                    ),
                  );

For this reason, when the Duration is zero (which is the default) I don't schedule a timer.

---

I tried the fix locally, using the path directive and it works with the changes in the following PR

[gskinner]

Hi @nank1ro . Thanks for the PR!

It's been a long time since I wrote that code, and I'm almost certain there was an important reason it introduces the zero length delay. I believe I had this optimization in place early on, but had to remove it.

I'm not certain, but it may have to do with ensuring callbacks and events fire in a predictable manner. Perhaps due to it causing race conditions when there are callbacks at 0 that make calls that can impact the animation.

Sorry for the vague response. I'll try to look into this in more detail soon — including writing a solid callback test if there isn't one already. Feel free to do some investigation on your end if you'd like though.

[nank1ro]

Hi @gskinner, do you have any updates about it?
i'm writing widget tests on shadcn_ui and doing some bad workarounds to handle this issue.
In case you want to keep it as it is, are you willing to make duration optional, so I can override the default duration of zero with null? In case it's null do not trigger the scheduler.

[gskinner]

Still digging into this.

Up until 02aa06d I had an inline comment // TODO: bypass if delay=0?, but I pulled that out during a documentation pass (6f20fdc).

Unfortunately, I don't have any documentation on why, just a vague memory of testing it and finding issues with race conditions in some situations. I'm hoping to spend a bit more time with it today to see if I can remember the rationale (or determine it isn't an issue).