Derive lobster Given/When/Then from gtest test names

lobster-gtest learned to derive the Given/When/Then specification from
conventionally named test cases of the form

    [<Prefix>_]Given<X>[_When<Y>]_(Expect|Then)<Z>

Enable that option for the gtest traces collected by the component rule,
so tests no longer have to repeat the information as record properties.
Record properties still take precedence over the test name.

The option does not exist before lobster 1.0.7, and passing an unknown
keyword argument to a subrule is an analysis error. Since Starlark cannot
introspect a subrule signature, a module extension probes lobster's own
rule definition and exposes the result as a load-time constant. Versions
without the option keep the previous behaviour, and bumping to a version
that provides it enables the derivation without a further change here.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Ehrja

MODULE.bazel

@@ -38,6 +38,15 @@ bazel_dep(name = "flatbuffers", version = "25.9.23")
 bazel_dep(name = "download_utils", version = "1.2.2")
 bazel_dep(name = "trlc", version = "3.0.1")
 bazel_dep(name = "lobster", version = "1.0.6")
+
+# Probes which optional features the resolved lobster module provides, so that
+# the rules can keep working with versions that predate them.
+lobster_capabilities = use_extension(
+    "//bazel/rules/rules_score/private:lobster_capabilities.bzl",
+    "lobster_capabilities",
+)
+use_repo(lobster_capabilities, "lobster_capabilities")
+
 bazel_dep(name = "rules_distroless", version = "0.8.0")
 bazel_dep(name = "googletest", version = "1.17.0.bcr.2")
 

bazel/rules/rules_score/private/component.bzl

@@ -20,6 +20,7 @@ with associated requirements and tests.
 """
 
 load("@lobster//:lobster.bzl", "subrule_lobster_gtest", "subrule_lobster_html_report", "subrule_lobster_report")
+load("@lobster_capabilities//:capabilities.bzl", "SUPPORTS_DERIVE_GWT_FROM_TEST_NAME")
 load("//bazel/rules/rules_score:providers.bzl", "AssumedSystemRequirementsInfo", "CertifiedScope", "ComponentInfo", "ComponentRequirementsInfo", "ComponentTestCaseCoverageInfo", "FeatureRequirementsInfo", "SphinxSourcesInfo", "UnitInfo")
 load("//bazel/rules/rules_score/private:lobster_config.bzl", "format_lobster_sources")
 
@@ -243,7 +244,15 @@ def _component_impl(ctx):
                 collected_architecture.append(component[ComponentInfo].architecture)
 
     # Convert unit test XML files to a single gtest.lobster file
-    gtest_lobster_file, provider = subrule_lobster_gtest(depset(transitive = collected_unit_test_files).to_list())
+    # Given/When/Then is derived from conventionally named test cases, so that
+    # tests do not have to repeat the information as record properties. Older
+    # lobster versions do not offer the option and keep relying on the record
+    # properties alone.
+    derive_gwt = {"derive_gwt_from_test_name": True} if SUPPORTS_DERIVE_GWT_FROM_TEST_NAME else {}
+    gtest_lobster_file, provider = subrule_lobster_gtest(
+        depset(transitive = collected_unit_test_files).to_list(),
+        **derive_gwt
+    )
 
     # -------------------------------------------------------------------------
     # Architecture Lobster: generate architecture.lobster for this component

bazel/rules/rules_score/private/lobster_capabilities.bzl

@@ -0,0 +1,67 @@
+# *******************************************************************************
+# Copyright (c) 2026 Contributors to the Eclipse Foundation
+#
+# See the NOTICE file(s) distributed with this work for additional
+# information regarding copyright ownership.
+#
+# This program and the accompanying materials are made available under the
+# terms of the Apache License Version 2.0 which is available at
+# https://www.apache.org/licenses/LICENSE-2.0
+#
+# SPDX-License-Identifier: Apache-2.0
+# *******************************************************************************
+"""Detect optional features of the resolved ``lobster`` module.
+
+``subrule_lobster_gtest`` gained the keyword argument
+``derive_gwt_from_test_name`` after the 1.0.6 release. Passing an unknown
+keyword argument to a subrule is an analysis error, and Starlark offers no way
+to introspect a subrule's signature, so the capability is probed by reading
+lobster's own rule definition.
+
+The result is exposed as a load-time constant through a generated repository,
+which lets the call sites choose the matching invocation. Pinning a lobster
+version that predates the feature therefore degrades to the previous behaviour
+instead of breaking the build, and bumping to a version that provides it
+enables the feature without any further change.
+"""
+
+_DERIVE_GWT_FROM_TEST_NAME = "derive_gwt_from_test_name"
+
+# Definition of the gtest rule inside the lobster module. A restructuring of
+# lobster makes the probe report "unsupported", which is the safe answer.
+_LOBSTER_GTEST_BZL = Label("@lobster//bazel/private:lobster_gtest.bzl")
+
+_CAPABILITIES_TEMPLATE = """\
+\"\"\"Generated by //bazel/rules/rules_score/private:lobster_capabilities.bzl.
+
+Do not edit. Describes the features of the lobster module that the current
+dependency resolution selected.
+\"\"\"
+
+# Whether subrule_lobster_gtest accepts the keyword argument
+# "derive_gwt_from_test_name".
+SUPPORTS_DERIVE_GWT_FROM_TEST_NAME = {derive_gwt_from_test_name}
+"""
+
+def _lobster_capabilities_repo_impl(repository_ctx):
+    definition = repository_ctx.read(repository_ctx.path(_LOBSTER_GTEST_BZL))
+    repository_ctx.file("BUILD.bazel", "")
+    repository_ctx.file(
+        "capabilities.bzl",
+        _CAPABILITIES_TEMPLATE.format(
+            derive_gwt_from_test_name = repr(_DERIVE_GWT_FROM_TEST_NAME in definition),
+        ),
+    )
+
+_lobster_capabilities_repo = repository_rule(
+    implementation = _lobster_capabilities_repo_impl,
+    doc = "Generates a .bzl file holding the probed lobster feature flags.",
+)
+
+def _lobster_capabilities_impl(_module_ctx):
+    _lobster_capabilities_repo(name = "lobster_capabilities")
+
+lobster_capabilities = module_extension(
+    implementation = _lobster_capabilities_impl,
+    doc = "Provides the @lobster_capabilities repository.",
+)