Move JUnitPlatform, SelectPackages and SelectClasses to a public API

[smoyer64]

Separating the JUnit 5 API from it's implementation provides a concise way for a test writer to know what classes can safely be used when writing tests. Pull request junit-team/junit5-samples#16 changes the Maven POM to only expose the JUnit 5 public APIs to test writers when using the Maven build system as the test runner.

As soon as you you also want to run these tests using a JUnit 4 runner (whether using the console or via Eclipse), you have to add the junit-platform-runner and the junit-jupiter-engine to the test-compile classpath. This results in the minimal dependencies shown in the referenced PR to expand to a large number of non-public classes as shown below:

[marcphilipp]

@smoyer64 I'm not sure I understand what you're asking for in this issue. You want to somehow minimize the dependencies... but how exactly?

[sbrannen]

I'm also confused: JUnitPlatform, @SelectPackages, and @SelectClasses are already public APIs that make the up the programming model for anyone who needs to use JUnit 4 infrastructure to launch the JUnit Platform.

So what exactly are you proposing we change?

[sbrannen]

@smoyer64 in light of #681, are you OK if I close this issue?

Or is there still something you would like to address beyond #681?

[sbrannen]

Superseded by #681.

[smoyer64]

Yes ... this should be closed as it was "clarified" by #681. I should have be more concise the first time but then again, I'd completely forgotten this issue by the time I wrote the other one!

[sbrannen]

OK. Thanks for the feedback.

BTW, does the implementation of #681 meet your needs/expectations?

[smoyer64]

Yes ... moving these annotations into another package eliminates the import of Vintage and JUnit 4. I think there are more uses for these annotations than just suites (we're really talking about limiting/hinting the discovery process) but I think people will find commonality between selecting tests for suites and selecting tests for various engines/runs.

Thanks for taking care of this!