1 files changed, 175 insertions, 0 deletions
diff --git a/src/cmd/gofmt/long_test.go b/src/cmd/gofmt/long_test.go
new file mode 100644
index 0000000..4a82170
--- /dev/null
+++ b/src/cmd/gofmt/long_test.go
@@ -0,0 +1,175 @@
+// Copyright 2011 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.
+
+// This test applies gofmt to all Go files under -root.
+// To test specific files provide a list of comma-separated
+// filenames via the -files flag: go test -files=gofmt.go .
+
+package main
+
+import (
+	"bytes"
+	"flag"
+	"fmt"
+	"go/ast"
+	"go/printer"
+	"go/token"
+	"io"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+)
+
+var (
+	root    = flag.String("root", runtime.GOROOT(), "test root directory")
+	files   = flag.String("files", "", "comma-separated list of files to test")
+	ngo     = flag.Int("n", runtime.NumCPU(), "number of goroutines used")
+	verbose = flag.Bool("verbose", false, "verbose mode")
+	nfiles  int // number of files processed
+)
+
+func gofmt(fset *token.FileSet, filename string, src *bytes.Buffer) error {
+	f, _, _, err := parse(fset, filename, src.Bytes(), false)
+	if err != nil {
+		return err
+	}
+	ast.SortImports(fset, f)
+	src.Reset()
+	return (&printer.Config{Mode: printerMode, Tabwidth: tabWidth}).Fprint(src, fset, f)
+}
+
+func testFile(t *testing.T, b1, b2 *bytes.Buffer, filename string) {
+	// open file
+	f, err := os.Open(filename)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	// read file
+	b1.Reset()
+	_, err = io.Copy(b1, f)
+	f.Close()
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	// exclude files w/ syntax errors (typically test cases)
+	fset := token.NewFileSet()
+	if _, _, _, err = parse(fset, filename, b1.Bytes(), false); err != nil {
+		if *verbose {
+			fmt.Fprintf(os.Stderr, "ignoring %s\n", err)
+		}
+		return
+	}
+
+	// gofmt file
+	if err = gofmt(fset, filename, b1); err != nil {
+		t.Errorf("1st gofmt failed: %v", err)
+		return
+	}
+
+	// make a copy of the result
+	b2.Reset()
+	b2.Write(b1.Bytes())
+
+	// gofmt result again
+	if err = gofmt(fset, filename, b2); err != nil {
+		t.Errorf("2nd gofmt failed: %v", err)
+		return
+	}
+
+	// the first and 2nd result should be identical
+	if !bytes.Equal(b1.Bytes(), b2.Bytes()) {
+		// A known instance of gofmt not being idempotent
+		// (see Issue #24472)
+		if strings.HasSuffix(filename, "issue22662.go") {
+			t.Log("known gofmt idempotency bug (Issue #24472)")
+			return
+		}
+		t.Errorf("gofmt %s not idempotent", filename)
+	}
+}
+
+func testFiles(t *testing.T, filenames <-chan string, done chan<- int) {
+	b1 := new(bytes.Buffer)
+	b2 := new(bytes.Buffer)
+	for filename := range filenames {
+		testFile(t, b1, b2, filename)
+	}
+	done <- 0
+}
+
+func genFilenames(t *testing.T, filenames chan<- string) {
+	defer close(filenames)
+
+	handleFile := func(filename string, d fs.DirEntry, err error) error {
+		if err != nil {
+			t.Error(err)
+			return nil
+		}
+		if isGoFile(d) {
+			filenames <- filename
+			nfiles++
+		}
+		return nil
+	}
+
+	// test Go files provided via -files, if any
+	if *files != "" {
+		for _, filename := range strings.Split(*files, ",") {
+			fi, err := os.Stat(filename)
+			handleFile(filename, &statDirEntry{fi}, err)
+		}
+		return // ignore files under -root
+	}
+
+	// otherwise, test all Go files under *root
+	filepath.WalkDir(*root, handleFile)
+}
+
+func TestAll(t *testing.T) {
+	if testing.Short() {
+		return
+	}
+
+	if *ngo < 1 {
+		*ngo = 1 // make sure test is run
+	}
+	if *verbose {
+		fmt.Printf("running test using %d goroutines\n", *ngo)
+	}
+
+	// generate filenames
+	filenames := make(chan string, 32)
+	go genFilenames(t, filenames)
+
+	// launch test goroutines
+	done := make(chan int)
+	for i := 0; i < *ngo; i++ {
+		go testFiles(t, filenames, done)
+	}
+
+	// wait for all test goroutines to complete
+	for i := 0; i < *ngo; i++ {
+		<-done
+	}
+
+	if *verbose {
+		fmt.Printf("processed %d files\n", nfiles)
+	}
+}
+
+type statDirEntry struct {
+	info fs.FileInfo
+}
+
+func (d *statDirEntry) Name() string               { return d.info.Name() }
+func (d *statDirEntry) IsDir() bool                { return d.info.IsDir() }
+func (d *statDirEntry) Type() fs.FileMode          { return d.info.Mode().Type() }
+func (d *statDirEntry) Info() (fs.FileInfo, error) { return d.info, nil }