1 files changed, 230 insertions, 12 deletions
diff --git a/src/pkg/go/printer/printer_test.go b/src/pkg/go/printer/printer_test.go
index ff2d906b5..497d671f2 100644
--- a/src/pkg/go/printer/printer_test.go
+++ b/src/pkg/go/printer/printer_test.go
@@ -7,10 +7,10 @@ package printer
 import (
 	"bytes"
 	"flag"
-	"io/ioutil"
 	"go/ast"
 	"go/parser"
 	"go/token"
+	"io/ioutil"
 	"path/filepath"
 	"testing"
 	"time"
@@ -62,11 +62,18 @@ func runcheck(t *testing.T, source, golden string, mode checkMode) {
 
 	// format source
 	var buf bytes.Buffer
-	if _, err := cfg.Fprint(&buf, fset, prog); err != nil {
+	if err := cfg.Fprint(&buf, fset, prog); err != nil {
 		t.Error(err)
 	}
 	res := buf.Bytes()
 
+	// formatted source must be valid
+	if _, err := parser.ParseFile(fset, "", res, 0); err != nil {
+		t.Error(err)
+		t.Logf("\n%s", res)
+		return
+	}
+
 	// update golden files if necessary
 	if *update {
 		if err := ioutil.WriteFile(golden, res, 0644); err != nil {
@@ -107,7 +114,7 @@ func check(t *testing.T, source, golden string, mode checkMode) {
 	// start a timer to produce a time-out signal
 	tc := make(chan int)
 	go func() {
-		time.Sleep(10e9) // plenty of a safety margin, even for very slow machines
+		time.Sleep(10 * time.Second) // plenty of a safety margin, even for very slow machines
 		tc <- 0
 	}()
 
@@ -133,7 +140,7 @@ type entry struct {
 	mode           checkMode
 }
 
-// Use gotest -update to create/update the respective golden files.
+// Use go test -update to create/update the respective golden files.
 var data = []entry{
 	{"empty.input", "empty.golden", 0},
 	{"comments.input", "comments.golden", 0},
@@ -147,15 +154,12 @@ var data = []entry{
 }
 
 func TestFiles(t *testing.T) {
-	for i, e := range data {
+	for _, e := range data {
 		source := filepath.Join(dataDir, e.source)
 		golden := filepath.Join(dataDir, e.golden)
 		check(t, source, golden, e.mode)
 		// TODO(gri) check that golden is idempotent
 		//check(t, golden, golden, e.mode)
-		if testing.Short() && i >= 3 {
-			break
-		}
 	}
 }
 
@@ -171,14 +175,14 @@ func TestLineComments(t *testing.T) {
 	`
 
 	fset := token.NewFileSet()
-	ast1, err1 := parser.ParseFile(fset, "", src, parser.ParseComments)
-	if err1 != nil {
-		panic(err1)
+	f, err := parser.ParseFile(fset, "", src, parser.ParseComments)
+	if err != nil {
+		panic(err) // error in test
 	}
 
 	var buf bytes.Buffer
 	fset = token.NewFileSet() // use the wrong file set
-	Fprint(&buf, fset, ast1)
+	Fprint(&buf, fset, f)
 
 	nlines := 0
 	for _, ch := range buf.Bytes() {
@@ -190,5 +194,219 @@ func TestLineComments(t *testing.T) {
 	const expected = 3
 	if nlines < expected {
 		t.Errorf("got %d, expected %d\n", nlines, expected)
+		t.Errorf("result:\n%s", buf.Bytes())
+	}
+}
+
+// Verify that the printer can be invoked during initialization.
+func init() {
+	const name = "foobar"
+	var buf bytes.Buffer
+	if err := Fprint(&buf, fset, &ast.Ident{Name: name}); err != nil {
+		panic(err) // error in test
+	}
+	// in debug mode, the result contains additional information;
+	// ignore it
+	if s := buf.String(); !debug && s != name {
+		panic("got " + s + ", want " + name)
+	}
+}
+
+// Verify that the printer doesn't crash if the AST contains BadXXX nodes.
+func TestBadNodes(t *testing.T) {
+	const src = "package p\n("
+	const res = "package p\nBadDecl\n"
+	f, err := parser.ParseFile(fset, "", src, parser.ParseComments)
+	if err == nil {
+		t.Error("expected illegal program") // error in test
+	}
+	var buf bytes.Buffer
+	Fprint(&buf, fset, f)
+	if buf.String() != res {
+		t.Errorf("got %q, expected %q", buf.String(), res)
+	}
+}
+
+// testComment verifies that f can be parsed again after printing it
+// with its first comment set to comment at any possible source offset.
+func testComment(t *testing.T, f *ast.File, srclen int, comment *ast.Comment) {
+	f.Comments[0].List[0] = comment
+	var buf bytes.Buffer
+	for offs := 0; offs <= srclen; offs++ {
+		buf.Reset()
+		// Printing f should result in a correct program no
+		// matter what the (incorrect) comment position is.
+		if err := Fprint(&buf, fset, f); err != nil {
+			t.Error(err)
+		}
+		if _, err := parser.ParseFile(fset, "", buf.Bytes(), 0); err != nil {
+			t.Fatalf("incorrect program for pos = %d:\n%s", comment.Slash, buf.String())
+		}
+		// Position information is just an offset.
+		// Move comment one byte down in the source.
+		comment.Slash++
+	}
+}
+
+// Verify that the printer produces always produces a correct program
+// even if the position information of comments introducing newlines
+// is incorrect.
+func TestBadComments(t *testing.T) {
+	const src = `
+// first comment - text and position changed by test
+package p
+import "fmt"
+const pi = 3.14 // rough circle
+var (
+	x, y, z int = 1, 2, 3
+	u, v float64
+)
+func fibo(n int) {
+	if n < 2 {
+		return n /* seed values */
+	}
+	return fibo(n-1) + fibo(n-2)
+}
+`
+
+	f, err := parser.ParseFile(fset, "", src, parser.ParseComments)
+	if err != nil {
+		t.Error(err) // error in test
+	}
+
+	comment := f.Comments[0].List[0]
+	pos := comment.Pos()
+	if fset.Position(pos).Offset != 1 {
+		t.Error("expected offset 1") // error in test
+	}
+
+	testComment(t, f, len(src), &ast.Comment{Slash: pos, Text: "//-style comment"})
+	testComment(t, f, len(src), &ast.Comment{Slash: pos, Text: "/*-style comment */"})
+	testComment(t, f, len(src), &ast.Comment{Slash: pos, Text: "/*-style \n comment */"})
+	testComment(t, f, len(src), &ast.Comment{Slash: pos, Text: "/*-style comment \n\n\n */"})
+}
+
+type visitor chan *ast.Ident
+
+func (v visitor) Visit(n ast.Node) (w ast.Visitor) {
+	if ident, ok := n.(*ast.Ident); ok {
+		v <- ident
+	}
+	return v
+}
+
+// idents is an iterator that returns all idents in f via the result channel.
+func idents(f *ast.File) <-chan *ast.Ident {
+	v := make(visitor)
+	go func() {
+		ast.Walk(v, f)
+		close(v)
+	}()
+	return v
+}
+
+// identCount returns the number of identifiers found in f.
+func identCount(f *ast.File) int {
+	n := 0
+	for _ = range idents(f) {
+		n++
 	}
+	return n
+}
+
+// Verify that the SourcePos mode emits correct //line comments
+// by testing that position information for matching identifiers
+// is maintained.
+func TestSourcePos(t *testing.T) {
+	const src = `
+package p
+import ( "go/printer"; "math" )
+const pi = 3.14; var x = 0
+type t struct{ x, y, z int; u, v, w float32 }
+func (t *t) foo(a, b, c int) int {
+	return a*t.x + b*t.y +
+		// two extra lines here
+		// ...
+		c*t.z
+}
+`
+
+	// parse original
+	f1, err := parser.ParseFile(fset, "src", src, parser.ParseComments)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// pretty-print original
+	var buf bytes.Buffer
+	err = (&Config{Mode: UseSpaces | SourcePos, Tabwidth: 8}).Fprint(&buf, fset, f1)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// parse pretty printed original
+	// (//line comments must be interpreted even w/o parser.ParseComments set)
+	f2, err := parser.ParseFile(fset, "", buf.Bytes(), 0)
+	if err != nil {
+		t.Fatalf("%s\n%s", err, buf.Bytes())
+	}
+
+	// At this point the position information of identifiers in f2 should
+	// match the position information of corresponding identifiers in f1.
+
+	// number of identifiers must be > 0 (test should run) and must match
+	n1 := identCount(f1)
+	n2 := identCount(f2)
+	if n1 == 0 {
+		t.Fatal("got no idents")
+	}
+	if n2 != n1 {
+		t.Errorf("got %d idents; want %d", n2, n1)
+	}
+
+	// verify that all identifiers have correct line information
+	i2range := idents(f2)
+	for i1 := range idents(f1) {
+		i2 := <-i2range
+
+		if i2.Name != i1.Name {
+			t.Errorf("got ident %s; want %s", i2.Name, i1.Name)
+		}
+
+		l1 := fset.Position(i1.Pos()).Line
+		l2 := fset.Position(i2.Pos()).Line
+		if l2 != l1 {
+			t.Errorf("got line %d; want %d for %s", l2, l1, i1.Name)
+		}
+	}
+
+	if t.Failed() {
+		t.Logf("\n%s", buf.Bytes())
+	}
+}
+
+// TextX is a skeleton test that can be filled in for debugging one-off cases.
+// Do not remove.
+func TestX(t *testing.T) {
+	const src = `
+package p
+func _() {}
+`
+	// parse original
+	f, err := parser.ParseFile(fset, "src", src, parser.ParseComments)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// pretty-print original
+	var buf bytes.Buffer
+	if err = (&Config{Mode: UseSpaces, Tabwidth: 8}).Fprint(&buf, fset, f); err != nil {
+		t.Fatal(err)
+	}
+
+	// parse pretty printed original
+	if _, err := parser.ParseFile(fset, "", buf.Bytes(), 0); err != nil {
+		t.Fatalf("%s\n%s", err, buf.Bytes())
+	}
+
 }