test: pin git background gc off in isolated test env (COR-394)

72ac486→main·

toothbrush·1mo ago·1 file·+15 added/-4 removed

GitIsolatedEnv/IsolateGitConfigEnv now point git at a config that disables gc.auto, gc.autoDetach, maintenance.auto, and fetch.writeCommitGraph. A detached git gc/git maintenance process could outlive a test while still holding .git/objects open, racing t.TempDir()'s deferred RemoveAll and failing with "directory not empty".

Fixes flaky TestSafelyAdvanceLocalRef_DoesNotReplayDisconnectedChainWhenTargetIsShallow; applied centrally so other git-shelling strategy tests don't regress.

Co-Authored-By: Claude Opus 4.8 (1M context) noreply@anthropic.com

Changes

1

• cmd/entire/cli/testutil

• Mtestutil.go+15/-4

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return found

// gitEmptyConfigPath returns the path to an empty file suitable for use as
// GIT_CONFIG_GLOBAL/GIT_CONFIG_SYSTEM. We use an empty file instead of
// gitEmptyConfigPath returns the path to a config file suitable for use as
// GIT_CONFIG_GLOBAL/GIT_CONFIG_SYSTEM. We use a real file instead of
// os.DevNull because git on Windows cannot open NUL as a config file.
//
// The file is not strictly empty: it pins background maintenance off so that
// no detached `git gc`/`git maintenance` process lingers after a test holding
// an open handle on the temp repo's .git/objects. Such a lingering process
// races t.TempDir()'s deferred RemoveAll and fails the test with
// "directory not empty" (see COR-394). Suppressing it centrally keeps every
// git-shelling test that uses GitIsolatedEnv/IsolateGitConfigEnv safe.
var gitEmptyConfig string
var gitEmptyConfigOnce sync.Once

func gitEmptyConfigPath() string {
    gitEmptyConfigOnce.Do(func() {
        f, err := os.CreateTemp("", "git-empty-config-*")
        f, err := os.CreateTemp("", "git-isolation-config-*")
        if err != nil {
            panic("create empty git config: " + err.Error())
            panic("create git isolation config: " + err.Error())
        }
        _, err = f.WriteString("[gc]\n\tauto = 0\n\tautoDetach = false\n[maintenance]\n\tauto = false\n[fetch]\n\twriteCommitGraph = false\n")
        if err != nil {
            panic("write git isolation config: " + err.Error())
        }
        _ = f.Close()
        gitEmptyConfig = f.Name()

Mcmd/entire/cli/testutil/testutil.go+15/-4