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// Copyright 2009 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 printer
import (
"bytes"
"errors"
"flag"
"fmt"
"go/ast"
"go/parser"
"go/token"
"io"
"io/ioutil"
"path/filepath"
"testing"
"time"
)
const (
dataDir = "testdata"
tabwidth = 8
)
var update = flag.Bool("update", false, "update golden files")
var fset = token.NewFileSet()
type checkMode uint
const (
export checkMode = 1 << iota
rawFormat
idempotent
)
// format parses src, prints the corresponding AST, verifies the resulting
// src is syntactically correct, and returns the resulting src or an error
// if any.
func format(src []byte, mode checkMode) ([]byte, error) {
// parse src
f, err := parser.ParseFile(fset, "", src, parser.ParseComments)
if err != nil {
return nil, fmt.Errorf("parse: %s\n%s", err, src)
}
// filter exports if necessary
if mode&export != 0 {
ast.FileExports(f) // ignore result
f.Comments = nil // don't print comments that are not in AST
}
// determine printer configuration
cfg := Config{Tabwidth: tabwidth}
if mode&rawFormat != 0 {
cfg.Mode |= RawFormat
}
// print AST
var buf bytes.Buffer
if err := cfg.Fprint(&buf, fset, f); err != nil {
return nil, fmt.Errorf("print: %s", err)
}
// make sure formatted output is syntactically correct
res := buf.Bytes()
if _, err := parser.ParseFile(fset, "", res, 0); err != nil {
return nil, fmt.Errorf("re-parse: %s\n%s", err, buf.Bytes())
}
return res, nil
}
// lineAt returns the line in text starting at offset offs.
func lineAt(text []byte, offs int) []byte {
i := offs
for i < len(text) && text[i] != '\n' {
i++
}
return text[offs:i]
}
// diff compares a and b.
func diff(aname, bname string, a, b []byte) error {
var buf bytes.Buffer // holding long error message
// compare lengths
if len(a) != len(b) {
fmt.Fprintf(&buf, "\nlength changed: len(%s) = %d, len(%s) = %d", aname, len(a), bname, len(b))
}
// compare contents
line := 1
offs := 1
for i := 0; i < len(a) && i < len(b); i++ {
ch := a[i]
if ch != b[i] {
fmt.Fprintf(&buf, "\n%s:%d:%d: %s", aname, line, i-offs+1, lineAt(a, offs))
fmt.Fprintf(&buf, "\n%s:%d:%d: %s", bname, line, i-offs+1, lineAt(b, offs))
fmt.Fprintf(&buf, "\n\n")
break
}
if ch == '\n' {
line++
offs = i + 1
}
}
if buf.Len() > 0 {
return errors.New(buf.String())
}
return nil
}
func runcheck(t *testing.T, source, golden string, mode checkMode) {
src, err := ioutil.ReadFile(source)
if err != nil {
t.Error(err)
return
}
res, err := format(src, mode)
if err != nil {
t.Error(err)
return
}
// update golden files if necessary
if *update {
if err := ioutil.WriteFile(golden, res, 0644); err != nil {
t.Error(err)
}
return
}
// get golden
gld, err := ioutil.ReadFile(golden)
if err != nil {
t.Error(err)
return
}
// formatted source and golden must be the same
if err := diff(source, golden, res, gld); err != nil {
t.Error(err)
return
}
if mode&idempotent != 0 {
// formatting golden must be idempotent
// (This is very difficult to achieve in general and for now
// it is only checked for files explicitly marked as such.)
res, err = format(gld, mode)
if err := diff(golden, fmt.Sprintf("format(%s)", golden), gld, res); err != nil {
t.Errorf("golden is not idempotent: %s", err)
}
}
}
func check(t *testing.T, source, golden string, mode checkMode) {
// run the test
cc := make(chan int)
go func() {
runcheck(t, source, golden, mode)
cc <- 0
}()
// wait with timeout
select {
case <-time.After(10 * time.Second): // plenty of a safety margin, even for very slow machines
// test running past time out
t.Errorf("%s: running too slowly", source)
case <-cc:
// test finished within allotted time margin
}
}
type entry struct {
source, golden string
mode checkMode
}
// Use go test -update to create/update the respective golden files.
var data = []entry{
{"empty.input", "empty.golden", idempotent},
{"comments.input", "comments.golden", 0},
{"comments.input", "comments.x", export},
{"comments2.input", "comments2.golden", idempotent},
{"linebreaks.input", "linebreaks.golden", idempotent},
{"expressions.input", "expressions.golden", idempotent},
{"expressions.input", "expressions.raw", rawFormat | idempotent},
{"declarations.input", "declarations.golden", 0},
{"statements.input", "statements.golden", 0},
{"slow.input", "slow.golden", idempotent},
}
func TestFiles(t *testing.T) {
t.Parallel()
for _, e := range data {
source := filepath.Join(dataDir, e.source)
golden := filepath.Join(dataDir, e.golden)
mode := e.mode
t.Run(e.source, func(t *testing.T) {
t.Parallel()
check(t, source, golden, mode)
// TODO(gri) check that golden is idempotent
//check(t, golden, golden, e.mode)
})
}
}
// TestLineComments, using a simple test case, checks that consecutive line
// comments are properly terminated with a newline even if the AST position
// information is incorrect.
//
func TestLineComments(t *testing.T) {
const src = `// comment 1
// comment 2
// comment 3
package main
`
fset := token.NewFileSet()
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, f)
nlines := 0
for _, ch := range buf.Bytes() {
if ch == '\n' {
nlines++
}
}
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 a correct program
// even if the position information of comments introducing newlines
// is incorrect.
func TestBadComments(t *testing.T) {
t.Parallel()
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 directives
// 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 directives 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())
}
}
// Verify that the SourcePos mode doesn't emit unnecessary //line directives
// before empty lines.
func TestIssue5945(t *testing.T) {
const orig = `
package p // line 2
func f() {} // line 3
var x, y, z int
func g() { // line 8
}
`
const want = `//line src.go:2
package p
//line src.go:3
func f() {}
var x, y, z int
//line src.go:8
func g() {
}
`
// parse original
f1, err := parser.ParseFile(fset, "src.go", orig, 0)
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)
}
got := buf.String()
// compare original with desired output
if got != want {
t.Errorf("got:\n%s\nwant:\n%s\n", got, want)
}
}
var decls = []string{
`import "fmt"`,
"const pi = 3.1415\nconst e = 2.71828\n\nvar x = pi",
"func sum(x, y int) int\t{ return x + y }",
}
func TestDeclLists(t *testing.T) {
for _, src := range decls {
file, err := parser.ParseFile(fset, "", "package p;"+src, parser.ParseComments)
if err != nil {
panic(err) // error in test
}
var buf bytes.Buffer
err = Fprint(&buf, fset, file.Decls) // only print declarations
if err != nil {
panic(err) // error in test
}
out := buf.String()
if out != src {
t.Errorf("\ngot : %q\nwant: %q\n", out, src)
}
}
}
var stmts = []string{
"i := 0",
"select {}\nvar a, b = 1, 2\nreturn a + b",
"go f()\ndefer func() {}()",
}
func TestStmtLists(t *testing.T) {
for _, src := range stmts {
file, err := parser.ParseFile(fset, "", "package p; func _() {"+src+"}", parser.ParseComments)
if err != nil {
panic(err) // error in test
}
var buf bytes.Buffer
err = Fprint(&buf, fset, file.Decls[0].(*ast.FuncDecl).Body.List) // only print statements
if err != nil {
panic(err) // error in test
}
out := buf.String()
if out != src {
t.Errorf("\ngot : %q\nwant: %q\n", out, src)
}
}
}
func TestBaseIndent(t *testing.T) {
t.Parallel()
// The testfile must not contain multi-line raw strings since those
// are not indented (because their values must not change) and make
// this test fail.
const filename = "printer.go"
src, err := ioutil.ReadFile(filename)
if err != nil {
panic(err) // error in test
}
file, err := parser.ParseFile(fset, filename, src, 0)
if err != nil {
panic(err) // error in test
}
for indent := 0; indent < 4; indent++ {
indent := indent
t.Run(fmt.Sprint(indent), func(t *testing.T) {
t.Parallel()
var buf bytes.Buffer
(&Config{Tabwidth: tabwidth, Indent: indent}).Fprint(&buf, fset, file)
// all code must be indented by at least 'indent' tabs
lines := bytes.Split(buf.Bytes(), []byte{'\n'})
for i, line := range lines {
if len(line) == 0 {
continue // empty lines don't have indentation
}
n := 0
for j, b := range line {
if b != '\t' {
// end of indentation
n = j
break
}
}
if n < indent {
t.Errorf("line %d: got only %d tabs; want at least %d: %q", i, n, indent, line)
}
}
})
}
}
// TestFuncType tests that an ast.FuncType with a nil Params field
// can be printed (per go/ast specification). Test case for issue 3870.
func TestFuncType(t *testing.T) {
src := &ast.File{
Name: &ast.Ident{Name: "p"},
Decls: []ast.Decl{
&ast.FuncDecl{
Name: &ast.Ident{Name: "f"},
Type: &ast.FuncType{},
},
},
}
var buf bytes.Buffer
if err := Fprint(&buf, fset, src); err != nil {
t.Fatal(err)
}
got := buf.String()
const want = `package p
func f()
`
if got != want {
t.Fatalf("got:\n%s\nwant:\n%s\n", got, want)
}
}
type limitWriter struct {
remaining int
errCount int
}
func (l *limitWriter) Write(buf []byte) (n int, err error) {
n = len(buf)
if n >= l.remaining {
n = l.remaining
err = io.EOF
l.errCount++
}
l.remaining -= n
return n, err
}
// Test whether the printer stops writing after the first error
func TestWriteErrors(t *testing.T) {
t.Parallel()
const filename = "printer.go"
src, err := ioutil.ReadFile(filename)
if err != nil {
panic(err) // error in test
}
file, err := parser.ParseFile(fset, filename, src, 0)
if err != nil {
panic(err) // error in test
}
for i := 0; i < 20; i++ {
lw := &limitWriter{remaining: i}
err := (&Config{Mode: RawFormat}).Fprint(lw, fset, file)
if lw.errCount > 1 {
t.Fatal("Writes continued after first error returned")
}
// We expect errCount be 1 iff err is set
if (lw.errCount != 0) != (err != nil) {
t.Fatal("Expected err when errCount != 0")
}
}
}
// 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 _() {}
`
_, err := format([]byte(src), 0)
if err != nil {
t.Error(err)
}
}
func TestCommentedNode(t *testing.T) {
const (
input = `package main
func foo() {
// comment inside func
}
// leading comment
type bar int // comment2
`
foo = `func foo() {
// comment inside func
}`
bar = `// leading comment
type bar int // comment2
`
)
fset := token.NewFileSet()
f, err := parser.ParseFile(fset, "input.go", input, parser.ParseComments)
if err != nil {
t.Fatal(err)
}
var buf bytes.Buffer
err = Fprint(&buf, fset, &CommentedNode{Node: f.Decls[0], Comments: f.Comments})
if err != nil {
t.Fatal(err)
}
if buf.String() != foo {
t.Errorf("got %q, want %q", buf.String(), foo)
}
buf.Reset()
err = Fprint(&buf, fset, &CommentedNode{Node: f.Decls[1], Comments: f.Comments})
if err != nil {
t.Fatal(err)
}
if buf.String() != bar {
t.Errorf("got %q, want %q", buf.String(), bar)
}
}