Provide built-in support for GraalVM native images

[sbrannen]

Overview

The GraalVM Native Build Tools (NBT) project provides support for running tests within a native image using the JUnit Platform. Since JUnit 5 has never provided built-in support for running in a native image, the NBT team implemented an internal PluginConfigProvider mechanism for contributing native image configuration for the JUnit Platform, JUnit Jupiter, and JUnit Vintage projects.

• PlatformConfigProvider
• JupiterConfigProvider
• VintageConfigProvider

The JUnitPlatformFeature also registers reflection for all test classes.

Rationale

The code in the above classes is very specific to JUnit 5 and can therefore be better maintained by the JUnit team. In addition, having the native image configuration directly in JUnit 5 artifacts will allow the JUnit team to proactively integration test support for GraalVM native images, thereby avoiding issues such as #3035.

Deliverables

• Add a new section on GraalVM native image support in the User Guide -- for example, in the "Running Tests" section.
• Introduce integration tests that run on the CI server which verify support for GraalVM native images without using Native Build Tools (as a companion to recently introduced integration tests that use NBT) -- for example, using the ConsoleLauncher as the application class for the compiled native image.
• Avoid build-time initialization in JUnit 5 wherever feasible and list the remaining classes in native-image.properties of each jar
• Determine how much of the functionality in the PluginConfigProvider implementations in NBT can be migrated to JUnit 5.
• Determine how much of the functionality in the JUnitPlatformFeature and its support classes can be migrated to JUnit 5.

[wilkinsona]

+1 for this. The breaking change in 5.10 that requires --initialize-at-build-time for two classes would be avoided if appropriate native-image.properties files were were included in the relevant jars.