Scope the xchart-demo test skip to the release build

[timmolter]

Follow-up to #1013, which surfaced this. Based on that branch — merge #1013 first, and GitHub will retarget this to develop automatically.

Problem

xchart-demo/pom.xml set maven.test.skip=true as a module-wide property. The intent (per the comment, added in f0936f8) was narrow: stop release:prepare's clean verify subprocess from compiling tests. The effect was broad — the module's 81 tests never ran in any build, including CI. Neither workflow overrides the property, so mvn clean verify on a PR silently skipped the whole module.

That is precisely how DemoChartsTest got to sit broken. It stopped compiling on 2026-05-22 when the ToolTips constructor gained parameters — one day after the skip landed. Nothing was there to catch it.

Change

Move the skip into a profile activated by a property, and have the release plugin pass that property to its forked builds:

<!-- xchart-demo/pom.xml -->
<profile>
  <id>skip-demo-tests</id>
  <activation><property><name>skipDemoTests</name></property></activation>
  <properties><maven.test.skip>true</maven.test.skip></properties>
</profile>

<!-- pom.xml, maven-release-plugin -->
<arguments>-DskipDemoTests=true</arguments>

release:prepare behaves exactly as it does today. Every other build runs the tests.

I deliberately did not reach for <arguments>-Dmaven.test.skip=true</arguments> on its own, since that would skip the xchart module's 154 tests during release too — a weaker release gate than what's in place now.

Verification

Both directions, plus the exact command CI runs:

mvn -pl xchart-demo test                      → Tests run: 81, Failures: 0, Errors: 0
mvn -pl xchart-demo test -DskipDemoTests=true → Tests are skipped.  BUILD SUCCESS

mvn clean verify -Dmaven.javadoc.skip=true -Dfmt.skip=true
  xchart      → Tests run: 154, Failures: 0, Errors: 0
  xchart-demo → Tests run: 81,  Failures: 0, Errors: 0
  BUILD SUCCESS

Since this newly exposes 80 rendering tests to CI, I also ran them under -Djava.awt.headless=true: all 81 pass. (DateChart01 was already excluded in SKIPPED_EXAMPLE_CHARTS for headless reasons.)

One thing I could not verify: I have no way to run an actual release:prepare here, so the release path is reasoned from the plugin's arguments semantics and the property-activation test above rather than observed end to end. Worth a dry run before the next release.

🤖 Generated with Claude Code