Git exports repository-local variables (GIT_DIR, GIT_INDEX_FILE,
GIT_WORK_TREE, ...) into hooks, and they take precedence over
`git -C <dir>`. Every fixture git command in the test runner therefore
acted on the caller's real repository whenever the suite ran with those
variables set: with GIT_DIR alone, fixture assertions failed and commits,
branches and linked worktrees were written into the caller's clone; with
the full hook set, fixture commits failed and git-dependent tests degraded
to "git not available" SKIPs. The pre-commit hook already clears the
variables (7883507d), but any other caller (a shell with GIT_DIR set, an
editor hook, `GIT_DIR=... scripts/test.sh`) still hit it.
The test runner and the repro runner now clear git's local-env list
(`git rev-parse --local-env-vars`) once at startup, before any fixture or
re-exec'd child spawns git, so every fixture scopes to its own repository
no matter who invokes the suite.
tests/test_git_env_isolation_contract.sh (Step 3a of scripts/test.sh)
drives the real runner's git_context suite with GIT_DIR, and with the full
hook set, aimed at a throwaway decoy repository. It requires the same
pass/skip summary as a clean run and a decoy left untouched (no refs, no
linked worktrees).
Signed-off-by: Martin Vogel <martin.vogel.tech@gmail.com>
Martin Vogel
cf72f1a657