Add Groovy 6 (alpha) executor variant with no-Spock fallback

[leonard84]

Why

Groovy 6.0.0-alpha-1 is out, but Spock has no Groovy 6-compatible release yet, and disabling Spock's Groovy version check (as we do for Groovy 5) is not viable here — there are real incompatibilities. This adds a Groovy 6 variant that ships without Spock and falls back gracefully.

What

Decouple Spock from the executor core behind a ServiceLoader SPI

• New gwc.spi.SpecSupport interface (runSpec / renderAst / spockVersion); GFunctionExecutor no longer imports any Spock type.
• gwc.spock.* moves to a profile-gated source root src/spock/, compiled only into the Groovy 3/4/5 variants via build-helper-maven-plugin, and registered as a provider (SpockSpecSupport) through META-INF/services.
• gwc.representations.ExecutionInfo also referenced Spock directly (SpockReleaseInfo); it now defaults spockVersion to n/a and is filled from the provider when present.

Fallback behavior (no provider on the classpath)

• Plain Groovy scripts run normally.
• A Spock spec or the AST view returns a clear message tied to the selected Groovy version, e.g. "Spock specifications are not supported on the selected Groovy version (6.0.0-alpha-1), because Spock has no release compatible with this Groovy version yet. Select a different Groovy version to use Spock; plain Groovy scripts work on all versions."

Build (Maven)

• New groovy.6.version property and groovy_6_0_alpha profile (no spock-core).
• spock-core + its runtime helpers (byte-buddy, objenesis, junit-platform-launcher) gated to the 3/4/5 profiles. The packaged G6 artifact contains groovy-6.0.0-alpha-1 and no Spock jars.
• The concrete alpha version lives only in groovy.6.version, so bumping alpha-1 → alpha-2 is a one-line change deployed to the same groovy_6_0_alpha function.

Tests — G6 fallback tests (plain JUnit 5, no Spock) in src/no-spock-test/ via a gmavenplus testSources override; existing Spock tests unchanged for 3/4/5.

CI — groovy_6_0_alpha (java 21) added to build + deploy matrices.

Frontend — nicer label for pre-release ids ("Groovy 6.0-alpha"). Because the runtime id contains alpha, the existing view.ts selection logic never picks it as the default version. Runtime discovery (list_runtimes) and labeling pick it up automatically.

Verification

All variants build green locally:

Variant	Result
groovy_3_0	10/10
groovy_4_0 (default)	10/10
groovy_5_0	10/10
groovy_6_0_alpha	4/4 fallback tests

G6 target/deployment/libs confirmed free of spock-core/byte-buddy/objenesis. Frontend lint passes.

Note: switching Maven profiles locally requires clean (documented in the README) — stale target/ classes from another profile otherwise cause a spock/lang/Specification failure on the Spock-free variant. CI is unaffected (fresh checkouts).

[Copilot]

Pull request overview

Adds a Groovy 6.0.0-alpha executor variant that ships without Spock by decoupling Spock-dependent functionality behind a ServiceLoader SPI and providing clear fallback behavior when the provider is absent.

Changes:

• Introduces gwc.spi.SpecSupport and switches GFunctionExecutor + ExecutionInfo to use an optional provider (fallback messaging when absent).
• Moves Spock implementation into a profile-gated source root (src/spock/) and registers it via META-INF/services.
• Adds a Groovy 6 alpha Maven profile (no Spock deps) + JUnit fallback tests and updates CI matrices + frontend version labeling.

Reviewed changes

Copilot reviewed 12 out of 21 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
services/frontend/src/ts/groovy-console.ts	Improves runtime label formatting for pre-release IDs (e.g., 6_0_alpha → 6.0-alpha).
README.md	Documents the new Groovy 6 alpha profile, Spock absence, and profile switching caveat.
functions/pom.xml	Adds groovy.6.version property for the new alpha variant.
functions/groovy-executor/src/main/java/gwc/spi/SpecSupport.java	Adds SPI interface to decouple Spock support from core executor.
functions/groovy-executor/src/main/java/gwc/GFunctionExecutor.java	Loads SpecSupport via ServiceLoader, adds fallback messages when absent.
functions/groovy-executor/src/main/java/gwc/representations/ExecutionInfo.java	Removes direct Spock reference; defaults spockVersion to n/a.
functions/groovy-executor/src/spock/resources/META-INF/services/gwc.spi.SpecSupport	Registers the Spock-backed SPI provider for Spock-enabled builds.
functions/groovy-executor/src/spock/java/gwc/spock/SpockSpecSupport.java	Implements SpecSupport using Spock runtime and AST tooling.
functions/groovy-executor/src/spock/java/gwc/spock/ScriptRunner.java	Spock spec execution runner (JUnit Platform launcher integration).
functions/groovy-executor/src/spock/java/gwc/spock/ScriptCompiler.java	Compiles Groovy scripts into spec classes for execution.
functions/groovy-executor/src/spock/java/gwc/spock/AstRenderer.java	Renders/transpiles AST using Spock’s embedded compiler utilities.
functions/groovy-executor/src/spock/java/gwc/spock/output/*	Adds tree-printing listener/printer utilities for rendered spec output.
functions/groovy-executor/src/no-spock-test/groovy/gwc/GFunctionExecutorFallbackTest.groovy	Adds JUnit fallback tests for the no-Spock (Groovy 6) variant.
functions/groovy-executor/pom.xml	Adds Groovy 6 alpha profile (no Spock deps) and profile-gated Spock sources/deps for 3/4/5.
.github/workflows/build-groovy-executor.yml	Adds groovy_6_0_alpha to build matrix.
.github/workflows/deploy-groovy-executor.yml	Adds groovy_6_0_alpha to deploy matrix.

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[glaforge]

Nice, great idea to already let users experience Groovy 6, although it's just an alpha!
Any ETA on when the Spock support will be added too?

[leonard84]

spockframework/spock#2356 still has some issues to resolve