- update functionality for printer test

- moved test files from data to testdata
- use tabs instead of spaces for layout

R=rsc
DELTA=129  (67 added, 60 deleted, 2 changed)
OCL=31353
CL=31360

src/pkg/go/printer/data/golden1.go

@@ -1,25 +0,0 @@
-package main
-
-import  "fmt" // fmt
-
-const c0 = 0 // zero
-
-const (
-    c1  = iota; // c1
-    c2  // c2
-)
-
-type T struct {
-    a, b, c int // 3 fields
-}
-
-var x int // x
-
-var ()
-
-func f0() {
-    const pi = 3.14;
-    var s1 struct {}
-    var s2 struct {} = struct {}{};
-    x := pi
-}

src/pkg/go/printer/printer_test.go

@@ -6,6 +6,7 @@ package printer
 
 import (
 	"bytes";
+	"flag";
 	"io";
 	"go/ast";
 	"go/parser";
@@ -18,12 +19,16 @@ import (
 
 
 const (
+	dataDir = "testdata";
 	tabwidth = 4;
 	padding = 1;
-	tabchar = ' ';
+	tabchar = '\t';
 )
 
 
+var update = flag.Bool("update", false, "update golden files");
+
+
 func lineString(text []byte, i int) string {
 	i0 := i;
 	for i < len(text) && text[i] != '\n' {
@@ -60,6 +65,14 @@ func check(t *testing.T, source, golden string, exports bool) {
 	w.Flush();
 	res := buf.Data();
 
+	// update golden files if necessary
+	if *update {
+		if err := io.WriteFile(golden, res, 0644); err != nil {
+			t.Error(err);
+		}
+		return;
+	}
+
 	// get golden
 	gld, err := io.ReadFile(golden);
 	if err != nil {
@@ -89,18 +102,12 @@ func check(t *testing.T, source, golden string, exports bool) {
 }
 
 
-const dataDir = "data";
-
 type entry struct {
 	source, golden string;
 	exports bool;
 }
 
-// Use gofmt to create/update the respective golden files:
-//
-//   gofmt source.go > golden.go
-//   gofmt -x source.go > golden.x
-//
+// Use gotest -update to create/update the respective golden files.
 var data = []entry{
 	entry{ "source1.go", "golden1.go", false },
 	entry{ "source1.go", "golden1.x", true },

src/pkg/go/printer/testdata/golden1.go

@@ -0,0 +1,25 @@
+package main
+
+import 	"fmt"	// fmt
+
+const c0	= 0	// zero
+
+const (
+	c1	= iota;	// c1
+	c2	// c2
+)
+
+type T struct {
+	a, b, c	int	// 3 fields
+}
+
+var x int	// x
+
+var ()
+
+func f0() {
+	const pi	= 3.14;
+	var s1 struct {}
+	var s2 struct {}	= struct {}{};
+	x := pi
+}