Welcome! package:test is the standard testing library for Dart and Flutter. If you have questions about Dart testing, please see the docs for package:test. package:test_api and package:test_core are implementation details and generally not user-facing.

package:checks is a relatively new library for expressing test expectations. It's a more modern version of package:matcher and features a literate API.

Package	Description	Version
checks	A framework for checking values against expectations and building custom expectations.
test	A full featured library for writing and running Dart tests across platforms.
test_api
test_core