HelloWorld can't run the testing

In the Helloworld sample testing , gralde did not include the

`testImplementation"androidx.car.app:app-testing:1.0.0-alpha01"`

https://developer.android.com/reference/kotlin/androidx/car/app/testing/package-summary

or declare any testing define in the hello world build.gradle

also missing robolectric / junit and others

the car testing can't run.

Open the HelloWorld sample's build.gradle and compare its test setup with the app-testing dependency and package documentation linked in the issue. Identify the missing testing declarations, then run the sample's tests to verify that car testing works and the required test dependencies resolve.

Written by the indexing model from the issue text.