RFR: 8296284: Update CONTRIBUTING guidelines to state that JUnit 5 is used for tests

[Andy Goryachev]

On Mon, 16 Jun 2025 15:35:59 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

>> CONTRIBUTING.md line 232:
>> 
>>> 230: * Wildcard imports – for example, `import java.util.*;` – are forbidden and may cause the build to fail. Please attempt to configure your IDE so it doesn't generate wildcard imports. An exception to this rule is that wildcard static imports in test classes are allowed, for example, `import static org.junit.jupiter.api.Assertions.*;`.
>>> 231: * Don't worry too much about import order. Try not to change it but don't worry about fighting your IDE to stop it from doing so.
>>> 232: * Tests are written using [JUnit5](https://junit.org/junit5/).
>> 
>> Should we mention about JUnit5 under **Test your changes** ([here](https://github.com/openjdk/jfx/blob/fd30c94893156644c0d803b3e7fd8c9731d65fe6/CONTRIBUTING.md?plain=1#L66)), where we mention that a fix should have associated tests?
>
> (if possible) ?

minor: maybe move L232 before L231?

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PR Review Comment: https://git.openjdk.org/jfx/pull/1828#discussion_r2150317254