This tests basic null safety use cases:

Sound null safety

An opted-in app (test_app/bin/test_app_sound.dart)) that uses an opted in package (test_pkg).

Run with:

$ cd test_app
$ dart run bin/test_app_sound.dart

Running with sound null safety: true
Hello: 42, null

Unsound null safety

An opted-in app (test_app/bin/test_app_unsound.dart)) that uses an opted in package (test_pkg) and an unmigrated package (test_pkg_unmigrated).

Run with:

$ cd test_app
$ dart --no-sound-null-safety run bin/test_app_unsound.dart

Running with sound null safety: false
Hello: 42, 42

Running tests

Sound tests

Run the sound test test with:

$ cd test_app
$ dart test test/test_app_test.dart

00:01 +3: All tests passed!

Unound tests

Run the unsound test test with:

$ cd test_app
$ dart --no-sound-null-safety test test/test_app_unsound_test.dart

00:01 +2: All tests passed!