Summary

Adds a new JVM-only integration test suite (ZIOAppIntegrationSpec) that verifies ZIOApp lifecycle behaviour by spawning real JVM sub-processes. This complements the existing in-process ZIOAppSpec (which uses invoke) by exercising the full main() path: JVM shutdown hooks, signal delivery, exit codes and gracefulShutdownTimeout.

Test coverage (13 tests across 5 suites)

Signal-based suites are gated behind a unixOnly aspect — Process.destroy() on Windows doesn’t trigger JVM shutdown hooks, so those tests are skipped there. CI runs on Linux so all 13 tests will execute.

Regression coverage

• #9901 — slow finalizer completes when gracefulShutdownTimeout is Infinity
• #9807 — atomic shuttingDown flag prevents shutdown-hook race (all signal tests exercise this path)
• #9240 — all fixture apps start without NoClassDefFoundError (reflection-based signal handler works)

How it works

Each test fixture is a small ZIOAppDefault / ZIOApp object in ZIOAppTestApps.scala. The parent test launches them with ProcessBuilder using the current test classpath, communicates through stdout markers (READY, FINALIZED, etc.), and sends kill -INT for signal tests.

Running

sbt "coreTestsJVM/testOnly zio.ZIOAppIntegrationSpec"

Files

• core-tests/jvm/src/test/scala/zio/ZIOAppTestApps.scala — 10 fixture apps
• core-tests/jvm/src/test/scala/zio/ZIOAppIntegrationSpec.scala — test spec

Relates to #9901, #9807, #9240.

/claim #9909