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_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.
|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.|