testenv.go

// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package testenv contains helper functions for skipping tests
// based on which tools are present in the environment.
package testenv

import (
	"bytes"
	"fmt"
	"io/ioutil"
	"os"
	"os/exec"
	"runtime"
	"runtime/debug"
	"testing"
)

// packageMainIsDevel reports whether the module containing package main
// is a development version (if module information is available).
func packageMainIsDevel() bool {
	info, ok := debug.ReadBuildInfo()
	if !ok {
		// Most test binaries currently lack build info, but this should become more
		// permissive once https://golang.org/issue/33976 is fixed.
		return true
	}

	// Note: info.Main.Version describes the version of the module containing
	// package main, not the version of “the main module”.
	// See https://golang.org/issue/33975.
	return info.Main.Version == "(devel)"
}

func hasTool(tool string) error {
	_, err := exec.LookPath(tool)
	if err != nil {
		return err
	}

	switch tool {
	case "patch":
		// check that the patch tools supports the -o argument
		temp, err := ioutil.TempFile("", "patch-test")
		if err != nil {
			return err
		}
		temp.Close()
		defer os.Remove(temp.Name())
		cmd := exec.Command(tool, "-o", temp.Name())
		if err := cmd.Run(); err != nil {
			return err
		}

	case "diff":
		// Check that diff is the GNU version, needed for the -u argument and
		// to report missing newlines at the end of files.
		out, err := exec.Command(tool, "-version").Output()
		if err != nil {
			return err
		}
		if !bytes.Contains(out, []byte("GNU diffutils")) {
			return fmt.Errorf("diff is not the GNU version")
		}
	}

	return nil
}

func allowMissingTool(tool string) bool {
	if runtime.GOOS == "android" {
		// Android builds generally run tests on a separate machine from the build,
		// so don't expect any external tools to be available.
		return true
	}

	switch tool {
	case "diff":
		if os.Getenv("GO_BUILDER_NAME") != "" {
			return true
		}
	case "patch":
		if os.Getenv("GO_BUILDER_NAME") != "" {
			return true
		}
	}

	// If a developer is actively working on this test, we expect them to have all
	// of its dependencies installed. However, if it's just a dependency of some
	// other module (for example, being run via 'go test all'), we should be more
	// tolerant of unusual environments.
	return !packageMainIsDevel()
}

// NeedsTool skips t if the named tool is not present in the path.
// As a special case, "cgo" means "go" is present and can compile cgo programs.
func NeedsTool(t testing.TB, tool string) {
	err := hasTool(tool)
	if err == nil {
		return
	}

	t.Helper()
	if allowMissingTool(tool) {
		t.Skipf("skipping because %s tool not available: %v", tool, err)
	} else {
		t.Fatalf("%s tool not available: %v", tool, err)
	}
}