bazel/go/bazel/bazel.go

// Package bazel contains utilities for Go tests running under Bazel.
package bazel

import (
	"os"
	"path/filepath"
)

// InBazel returns true if running under Bazel with either "bazel test" or "bazel run", or false
// otherwise.
func InBazel() bool {
	return InBazelRun() || InBazelTest()
}

// InBazelRun returns true if running under Bazel with "bazel run", or false otherwise.
func InBazelRun() bool {
	// See https://bazel.build/docs/user-manual#running-executables.
	//
	// This environment variable is not set for "bazel test" commands. Verified empirically against
	// Bazel 6.0.0.
	return os.Getenv("BUILD_WORKSPACE_DIRECTORY") != ""
}

// InBazelTest returns true if running under Bazel with "bazel test", or false otherwise.
func InBazelTest() bool {
	// See https://docs.bazel.build/versions/master/test-encyclopedia.html#initial-conditions.
	return os.Getenv("TEST_WORKSPACE") != ""
}

// InBazelTestOnRBE returns true if running under Bazel on RBE (e.g. "bazel test --config=remote"),
// or false otherwise.
func InBazelTestOnRBE() bool {
	// The BAZEL_REMOTE environment variable is set in //.bazelrc when running with --config=remote.
	return InBazelTest() && os.Getenv("BAZEL_REMOTE") == "true"
}

// RunfilesDir returns the path to the directory under which a Bazel-built binary or test can find
// its runfiles (e.g. files included in the "data" attribute of *_test targets) using relative
// paths.
//
// It panics if the program is not running under Bazel.
func RunfilesDir() string {
	if InBazelRun() {
		// Verified empirically against Bazel 6.0.0.
		return os.Getenv("PWD")
	}

	if InBazelTest() {
		// See https://bazel.build/extending/rules#runfiles_location and
		// https://bazel.build/reference/test-encyclopedia#initial-conditions.
		return filepath.Join(os.Getenv("RUNFILES_DIR"), os.Getenv("TEST_WORKSPACE"))
	}

	panic("This program is not running under Bazel. Suggestion: Only call this function if bazel.InBazel() returns true.")
}