TestWidgetsFlutterBinding.clock change

The TestWidgetsFlutterBinding.clock now comes from package:clock and not package:quiver.

The flutter_test package is removing its dependency on the heavier weight quiver package in favor of a dependency on two more targeted and lighter weight packages, clock and fake_async.

This can affect user code which grabs the clock from a TestWidgetsFlutterBinding and passes that to an API that expects a Clock from package:quiver, for example some code like this:

testWidgets('some test', (WidgetTester tester) {
  someApiThatWantsAQuiverClock(tester.binding.clock);
});

The error you might see after this change looks something like this:

Error: The argument type 'Clock/*1*/' can't be assigned to the parameter type 'Clock/*2*/'.
 - 'Clock/*1*/' is from 'package:clock/src/clock.dart' ('<pub-cache>/clock/lib/src/clock.dart').
 - 'Clock/*2*/' is from 'package:quiver/time.dart' ('<pub-cache>/quiver/lib/time.dart').

The easiest migration is to create a package:quiver clock from the package:clock clock, which can be done by passing the .now function tearoff to the Clock constructor:

Code before migration:

testWidgets('some test', (WidgetTester tester) {
  someApiThatWantsAQuiverClock(tester.binding.clock);
});

Code after migration:

testWidgets('some test', (WidgetTester tester) {
  someApiThatWantsAQuiverClock(Clock(tester.binding.clock.now));
});

If you own the api you are calling, you may want to change it to accept a Clock from package:clock. This is a judgement call based on how many places are calling this API with something other than a clock retrieved from a TestWidgetsFlutterBinding.

If you go this route, your call sites that are passing tester.binding.clock won't need to be modified, but other call sites will.

If you only use the Clock for its now function, and you control the API, then you can also change it to accept that function directly instead of a Clock. This makes it easily callable with either type of Clock, by passing a tearoff of the now method from either type of clock:

Calling code before migration:

testWidgets('some test', (WidgetTester tester) {
  someApiThatWantsAQuiverClock(tester.binding.clock);
});

Calling code after migration:

testWidgets('some test', (WidgetTester tester) {
  modifiedApiThatTakesANowFunction(tester.binding.clock.now);
});

Landed in version: 1.18.0
In stable release: 1.20

API documentation:

• TestWidgetsFlutterBinding

Relevant PRs:

• PR 54125: remove flutter_test quiver dep, use fake_async and clock instead

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