internal/pkg/testsetup/setup.go

// Copyright 2026 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Package testsetup provides a global init() shim to ensure glog is isolated
// in test environments. This package should be imported (potentially as a
// blank import) by every test to prevent collisions on /tmp when running
// parallel tests (e.g. --runs_per_test).
package testsetup

import (
	"flag"
	"os"
)

func init() {
	// If running under Bazel's test runner and no log directory has been
	// explicitly set, default glog output and Go's temp directory to the
	// private test temporary directory. This ensures that parallel test runs
	// of the same target do not collide when trying to create log files
	// or symlinks in /tmp.
	if testTmp := os.Getenv("TEST_TMPDIR"); testTmp != "" {
		// Fix Go's standard temp directory for the process.
		os.Setenv("TMPDIR", testTmp)

		// Explicitly tell glog to use it, preventing /tmp collisions for
		// libraries that don't respect TMPDIR.
		if f := flag.Lookup("log_dir"); f != nil && f.Value.String() == "" {
			f.Value.Set(testTmp)
		}
	}
}