Gradle --global-prefix e2e tests pass without --global-prefix: the harness always sets GRADLE_USER_HOME, and no test asserts gradle_user_home_differs fires #1982

[agent] Filed by the scheduled architecture audit (audit-cli-tests). Register: register.

Kind: bug (fake tests). Register ID: T67.

Problem

Two Gradle tests claim to prove --global-prefix behavior, but the harness makes the flag irrelevant to their assertions.

e2e_gradle_discovery_build.rs. global_prefix_scan_says_nothing_about_the_user_home`` asserts that gradle_user_home_differs is absent. The warning can't appear in this harness, because:

• the scan goes through jvm_env::isolate_cli, which always sets GRADLE_USER_HOME (jvm_env.rs L106-L109);
• the core check returns None whenever GRADLE_USER_HOME is set (gradle_cache.rs L551-L566).```

Executed on cbbbdb9 with a scratch build, running scan --json in a Gradle project with HOME ≠ passwd home:

So the assertion holds whether or not --global-prefix suppresses the warning. The suite's scan doc at L111 says None means "no GRADLE_USER_HOME", which is false. No CLI test anywhere asserts that gradle_user_home_differs fires.

e2e_gradle_agent_build.rs. gradle_agent_global_prefix runs through socket(), which sets GRADLE_USER_HOME to the same cache (L333).````` A plain apply --offline already patches that cache (L468), so a CLI that ignored `--global-prefix` would still pass. This one comes from reading the code and was not executed.

Proposed change

For the discovery test:

• Remove GRADLE_USER_HOME after prepare_command.
• Add a positive control: the same scan without --global-prefix asserts gradle_user_home_differs is present.
• Then assert it is absent with the flag.
• Fix the L111 doc.

For the agent test:

• Remove GRADLE_USER_HOME, or point it at an empty dir, so only --global-prefix names the cache.
• Assert the jar is patched there and untouched under the default home.

Size

2 test files. About +30/−10 lines.

Acceptance criteria

• Each test fails when --global-prefix handling is stubbed out. Show this once by mutation in the PR description.
• The new positive control passes on main.