message/pipeline: avoid writing to the testdata directory

If this test is run as a dependency of some other module, the testdata
directory will be read-only. Moreover, if temporary files are written
to the working directory they are likely to interfere with concurrent
version-control operations, such as 'git commit -a'.

Updates golang/go#28387

Change-Id: I15cd9408c63f9b6aed50facbfefa26299392052f
Reviewed-on: https://go-review.googlesource.com/c/text/+/208123
Run-TryBot: Bryan C. Mills <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Marcel van Lohuizen <[email protected]>

Author: Bryan C. Mills

message/pipeline/generate.go

@@ -49,10 +49,14 @@ func (s *State) Generate() error {
 		return err
 	}
 	if !isDir {
-		gopath := build.Default.GOPATH
-		path = filepath.Join(gopath, filepath.FromSlash(pkgs[0].Pkg.Path()))
+		gopath := filepath.SplitList(build.Default.GOPATH)[0]
+		path = filepath.Join(gopath, "src", filepath.FromSlash(pkgs[0].Pkg.Path()))
+	}
+	if filepath.IsAbs(s.Config.GenFile) {
+		path = s.Config.GenFile
+	} else {
+		path = filepath.Join(path, s.Config.GenFile)
 	}
-	path = filepath.Join(path, s.Config.GenFile)
 	cw.WriteGoFile(path, pkg) // TODO: WriteGoFile should return error.
 	return err
 }

message/pipeline/pipeline_test.go

@@ -10,11 +10,13 @@ import (
 	"encoding/json"
 	"flag"
 	"fmt"
+	"go/build"
 	"io/ioutil"
 	"os"
 	"os/exec"
 	"path"
 	"path/filepath"
+	"reflect"
 	"runtime"
 	"strings"
 	"testing"
@@ -35,28 +37,59 @@ func TestFullCycle(t *testing.T) {
 		t.Skipf("skipping because 'go' command is unavailable: %v", err)
 	}
 
-	const path = "./testdata"
-	dirs, err := ioutil.ReadDir(path)
+	GOPATH, err := ioutil.TempDir("", "pipeline_test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(GOPATH)
+	testdata := filepath.Join(GOPATH, "src", "testdata")
+
+	// Copy the testdata contents into a new module.
+	copyTestdata(t, testdata)
+	initTestdataModule(t, testdata)
+
+	// Several places hard-code the use of build.Default.
+	// Adjust it to match the test's temporary GOPATH.
+	defer func(prev string) { build.Default.GOPATH = prev }(build.Default.GOPATH)
+	build.Default.GOPATH = GOPATH + string(filepath.ListSeparator) + build.Default.GOPATH
+	if wd := reflect.ValueOf(&build.Default).Elem().FieldByName("WorkingDir"); wd.IsValid() {
+		defer func(prev string) { wd.SetString(prev) }(wd.String())
+		wd.SetString(testdata)
+	}
+
+	// To work around https://golang.org/issue/34860, execute the commands
+	// that (transitively) use go/build in the working directory of the
+	// corresponding module.
+	wd, _ := os.Getwd()
+	defer os.Chdir(wd)
+
+	dirs, err := ioutil.ReadDir(testdata)
 	if err != nil {
 		t.Fatal(err)
 	}
 	for _, f := range dirs {
+		if !f.IsDir() {
+			continue
+		}
 		t.Run(f.Name(), func(t *testing.T) {
 			chk := func(t *testing.T, err error) {
 				setHelper(t)
 				if err != nil {
 					t.Fatal(err)
 				}
 			}
-			dir := filepath.Join(path, f.Name())
-			pkgPath := fmt.Sprintf("%s/%s", path, f.Name())
+			dir := filepath.Join(testdata, f.Name())
+			pkgPath := "testdata/" + f.Name()
 			config := Config{
 				SourceLanguage: language.AmericanEnglish,
 				Packages:       []string{pkgPath},
 				Dir:            filepath.Join(dir, "locales"),
 				GenFile:        "catalog_gen.go",
 				GenPackage:     pkgPath,
 			}
+
+			os.Chdir(dir)
+
 			// TODO: load config if available.
 			s, err := Extract(&config)
 			chk(t, err)
@@ -69,34 +102,82 @@ func TestFullCycle(t *testing.T) {
 			chk(t, s.Export())
 			chk(t, s.Generate())
 
+			os.Chdir(wd)
+
 			writeJSON(t, filepath.Join(dir, "extracted.gotext.json"), s.Extracted)
-			checkOutput(t, dir)
+			checkOutput(t, dir, f.Name())
 		})
 	}
 }
 
-func checkOutput(t *testing.T, p string) {
-	filepath.Walk(p, func(p string, f os.FileInfo, err error) error {
+func copyTestdata(t *testing.T, dst string) {
+	err := filepath.Walk("testdata", func(p string, f os.FileInfo, err error) error {
+		if p == "testdata" || strings.HasSuffix(p, ".want") {
+			return nil
+		}
+
+		rel := strings.TrimPrefix(p, "testdata"+string(filepath.Separator))
+		if f.IsDir() {
+			return os.MkdirAll(filepath.Join(dst, rel), 0755)
+		}
+
+		data, err := ioutil.ReadFile(p)
+		if err != nil {
+			return err
+		}
+		return ioutil.WriteFile(filepath.Join(dst, rel), data, 0644)
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func initTestdataModule(t *testing.T, dst string) {
+	xTextDir, err := filepath.Abs("../..")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	goMod := fmt.Sprintf(`module testdata
+go 1.11
+require golang.org/x/text v0.0.0-00010101000000-000000000000
+replace golang.org/x/text v0.0.0-00010101000000-000000000000 => %s
+`, xTextDir)
+	if err := ioutil.WriteFile(filepath.Join(dst, "go.mod"), []byte(goMod), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	data, err := ioutil.ReadFile(filepath.Join(xTextDir, "go.sum"))
+	if err := ioutil.WriteFile(filepath.Join(dst, "go.sum"), data, 0644); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func checkOutput(t *testing.T, gen string, testdataDir string) {
+	err := filepath.Walk(gen, func(gotFile string, f os.FileInfo, err error) error {
 		if f.IsDir() {
 			return nil
 		}
-		if filepath.Ext(p) != ".want" {
+		rel := strings.TrimPrefix(gotFile, gen+string(filepath.Separator))
+
+		wantFile := filepath.Join("testdata", testdataDir, rel+".want")
+		if _, err := os.Stat(wantFile); os.IsNotExist(err) {
 			return nil
 		}
-		gotFile := p[:len(p)-len(".want")]
+
 		got, err := ioutil.ReadFile(gotFile)
 		if err != nil {
-			t.Errorf("failed to read %q", p)
+			t.Errorf("failed to read %q", gotFile)
 			return nil
 		}
 		if *genFiles {
-			if err := ioutil.WriteFile(p, got, 0644); err != nil {
+			if err := ioutil.WriteFile(wantFile, got, 0644); err != nil {
 				t.Fatal(err)
 			}
 		}
-		want, err := ioutil.ReadFile(p)
+		want, err := ioutil.ReadFile(wantFile)
 		if err != nil {
-			t.Errorf("failed to read %q", p)
+			t.Errorf("failed to read %q", wantFile)
 		} else {
 			scanGot := bufio.NewScanner(bytes.NewReader(got))
 			scanWant := bufio.NewScanner(bytes.NewReader(want))
@@ -122,6 +203,9 @@ func checkOutput(t *testing.T, p string) {
 		}
 		return nil
 	})
+	if err != nil {
+		t.Fatal(err)
+	}
 }
 
 func writeJSON(t *testing.T, path string, x interface{}) {