every version of flutter_test from sdk depends on test_api 0.4.8, mockito >=4.1.2 <=5.0.0-nullsafety.7 is incompatible with flutter_test from sdk - flutter

Question

pubspec.yaml:
name: my_chat_app
description: A new Flutter application.
# The following line prevents the package from being accidentally published to
# pub.dev using `flutter pub publish`. This is preferred for private packages.
publish_to: 'none' # Remove this line if you wish to publish to pub.dev
version: 1.0.0+1
environment:
sdk: ">=2.7.0 <3.0.0"
dependencies:
flutter:
sdk: flutter
chat:
path: ./chat
sqflite: ^2.0.0+3
cupertino_icons: ^1.0.2
dev_dependencies:
flutter_test:
sdk: flutter
mockito: ^4.1.4
flutter_lints: ^1.0.0
# The following section is specific to Flutter.
flutter:
chat/pubspec.yaml:
name: chat
description: A new Flutter package project.
environment:
sdk: ">=2.16.1 <3.0.0"
flutter: ">=1.17.0"
dependencies:
flutter:
sdk: flutter
rethinkdb_dart: ^2.3.2+6
encrypt: ^4.0.1
dev_dependencies:
flutter_test:
sdk: flutter
flutter_lints: ^1.0.0
flutter:
flutter pub get output in pubspec.yaml:
Running "flutter pub get" in my_chat_app...
Because mockito >=4.1.2 <=5.0.0-nullsafety.7 depends on test_api ^0.2.19-nullsafety and every version of flutter_test from sdk depends on test_api 0.4.8, mockito >=4.1.2 <=5.0.0-nullsafety.7 is incompatible with flutter_test from sdk.
So, because my_chat_app depends on both flutter_test from sdk and mockito ^4.1.4, version solving failed.
pub get failed (1; So, because my_chat_app depends on both flutter_test from sdk and mockito ^4.1.4, version solving failed.)
Process finished with exit code 1