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) {

Migration guide

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').

Option #1: Create a package:quiver Clock from a package:clock Clock

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) {

Code after migration:

testWidgets('some test', (WidgetTester tester) {

Option #2: Change the api to accept a package:clock Clock

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.

Option #3: Change the API to accept a DateTime function()

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) {

Calling code after migration:

testWidgets('some test', (WidgetTester tester) {


Landed in version: 1.18.0
In stable release: 1.20


API documentation:

Relevant PRs:

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