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// 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.
package template
import (
var debug = flag.Bool("debug", false, "show the errors produced by the tests")
// T has lots of interesting pieces to use to test execution.
type T struct {
// Basics
True bool
I int
U16 uint16
X string
FloatZero float64
ComplexZero float64
// Nested structs.
U *U
// Struct with String method.
V0 V
V1, V2 *V
// Slices
SI []int
SIEmpty []int
SB []bool
// Maps
MSI map[string]int
MSIone map[string]int // one element, for deterministic output
MSIEmpty map[string]int
MXI map[interface{}]int
MII map[int]int
SMSI []map[string]int
// Empty interfaces; used to see if we can dig inside one.
Empty0 interface{} // nil
Empty1 interface{}
Empty2 interface{}
Empty3 interface{}
Empty4 interface{}
// Non-empty interface.
NonEmptyInterface I
// Stringer.
Str fmt.Stringer
// Pointers
PI *int
PSI *[]int
NIL *int
// Template to test evaluation of templates.
Tmpl *Template
type U struct {
V string
type V struct {
j int
func (v *V) String() string {
if v == nil {
return "nilV"
return fmt.Sprintf("<%d>", v.j)
var tVal = &T{
True: true,
I: 17,
U16: 16,
X: "x",
U: &U{"v"},
V0: V{6666},
V1: &V{7777}, // leave V2 as nil
SI: []int{3, 4, 5},
SB: []bool{true, false},
MSI: map[string]int{"one": 1, "two": 2, "three": 3},
MSIone: map[string]int{"one": 1},
MXI: map[interface{}]int{"one": 1},
MII: map[int]int{1: 1},
SMSI: []map[string]int{
{"one": 1, "two": 2},
{"eleven": 11, "twelve": 12},
Empty1: 3,
Empty2: "empty2",
Empty3: []int{7, 8},
Empty4: &U{"UinEmpty"},
NonEmptyInterface: new(T),
Str: os.NewError("foozle"),
PI: newInt(23),
PSI: newIntSlice(21, 22, 23),
Tmpl: Must(New("x").Parse("test template")), // "x" is the value of .X
// A non-empty interface.
type I interface {
Method0() string
var iVal I = tVal
// Helpers for creation.
func newInt(n int) *int {
p := new(int)
*p = n
return p
func newIntSlice(n *[]int {
p := new([]int)
*p = make([]int, len(n))
copy(*p, n)
return p
// Simple methods with and without arguments.
func (t *T) Method0() string {
return "M0"
func (t *T) Method1(a int) int {
return a
func (t *T) Method2(a uint16, b string) string {
return fmt.Sprintf("Method2: %d %s", a, b)
func (t *T) MAdd(a int, b []int) []int {
v := make([]int, len(b))
for i, x := range b {
v[i] = x + a
return v
// MSort is used to sort map keys for stable output. (Nice trick!)
func (t *T) MSort(m map[string]int) []string {
keys := make([]string, len(m))
i := 0
for k := range m {
keys[i] = k
return keys
// EPERM returns a value and an os.Error according to its argument.
func (t *T) EPERM(error bool) (bool, os.Error) {
if error {
return true, os.EPERM
return false, nil
// A few methods to test chaining.
func (t *T) GetU() *U {
return t.U
func (u *U) TrueFalse(b bool) string {
if b {
return "true"
return ""
func typeOf(arg interface{}) string {
return fmt.Sprintf("%T", arg)
type execTest struct {
name string
input string
output string
data interface{}
ok bool
// bigInt and bigUint are hex string representing numbers either side
// of the max int boundary.
// We do it this way so the test doesn't depend on ints being 32 bits.
var (
bigInt = fmt.Sprintf("0x%x", int(1<<uint(reflect.TypeOf(0).Bits()-1)-1))
bigUint = fmt.Sprintf("0x%x", uint(1<<uint(reflect.TypeOf(0).Bits()-1)))
var execTests = []execTest{
// Trivial cases.
{"empty", "", "", nil, true},
{"text", "some text", "some text", nil, true},
// Ideal constants.
{"ideal int", "{{typeOf 3}}", "int", 0, true},
{"ideal float", "{{typeOf 1.0}}", "float64", 0, true},
{"ideal exp float", "{{typeOf 1e1}}", "float64", 0, true},
{"ideal complex", "{{typeOf 1i}}", "complex128", 0, true},
{"ideal int", "{{typeOf " + bigInt + "}}", "int", 0, true},
{"ideal too big", "{{typeOf " + bigUint + "}}", "", 0, false},
// Fields of structs.
{".X", "-{{.X}}-", "-x-", tVal, true},
{".U.V", "-{{.U.V}}-", "-v-", tVal, true},
// Fields on maps.
{"map .one", "{{}}", "1", tVal, true},
{"map .two", "{{.MSI.two}}", "2", tVal, true},
{"map .NO", "{{.MSI.NO}}", "<no value>", tVal, true},
{"map .one interface", "{{}}", "1", tVal, true},
{"map .WRONG args", "{{ 1}}", "", tVal, false},
{"map .WRONG type", "{{}}", "", tVal, false},
// Dots of all kinds to test basic evaluation.
{"dot int", "<{{.}}>", "<13>", 13, true},
{"dot uint", "<{{.}}>", "<14>", uint(14), true},
{"dot float", "<{{.}}>", "<15.1>", 15.1, true},
{"dot bool", "<{{.}}>", "<true>", true, true},
{"dot complex", "<{{.}}>", "<(16.2-17i)>", 16.2 - 17i, true},
{"dot string", "<{{.}}>", "<hello>", "hello", true},
{"dot slice", "<{{.}}>", "<[-1 -2 -3]>", []int{-1, -2, -3}, true},
{"dot map", "<{{.}}>", "<map[two:22 one:11]>", map[string]int{"one": 11, "two": 22}, true},
{"dot struct", "<{{.}}>", "<{7 seven}>", struct {
a int
b string
}{7, "seven"}, true},
// Variables.
{"$ int", "{{$}}", "123", 123, true},
{"$.I", "{{$.I}}", "17", tVal, true},
{"$.U.V", "{{$.U.V}}", "v", tVal, true},
{"declare in action", "{{$x := $.U.V}}{{$x}}", "v", tVal, true},
// Type with String method.
{"V{6666}.String()", "-{{.V0}}-", "-<6666>-", tVal, true},
{"&V{7777}.String()", "-{{.V1}}-", "-<7777>-", tVal, true},
{"(*V)(nil).String()", "-{{.V2}}-", "-nilV-", tVal, true},
// Pointers.
{"*int", "{{.PI}}", "23", tVal, true},
{"*[]int", "{{.PSI}}", "[21 22 23]", tVal, true},
{"*[]int[1]", "{{index .PSI 1}}", "22", tVal, true},
{"NIL", "{{.NIL}}", "<nil>", tVal, true},
// Empty interfaces holding values.
{"empty nil", "{{.Empty0}}", "<no value>", tVal, true},
{"empty with int", "{{.Empty1}}", "3", tVal, true},
{"empty with string", "{{.Empty2}}", "empty2", tVal, true},
{"empty with slice", "{{.Empty3}}", "[7 8]", tVal, true},
{"empty with struct", "{{.Empty4}}", "{UinEmpty}", tVal, true},
{"empty with struct, field", "{{.Empty4.V}}", "UinEmpty", tVal, true},
// Method calls.
{".Method0", "-{{.Method0}}-", "-M0-", tVal, true},
{".Method1(1234)", "-{{.Method1 1234}}-", "-1234-", tVal, true},
{".Method1(.I)", "-{{.Method1 .I}}-", "-17-", tVal, true},
{".Method2(3, .X)", "-{{.Method2 3 .X}}-", "-Method2: 3 x-", tVal, true},
{".Method2(.U16, `str`)", "-{{.Method2 .U16 `str`}}-", "-Method2: 16 str-", tVal, true},
{".Method2(.U16, $x)", "{{if $x := .X}}-{{.Method2 .U16 $x}}{{end}}-", "-Method2: 16 x-", tVal, true},
{"method on var", "{{if $x := .}}-{{$x.Method2 .U16 $x.X}}{{end}}-", "-Method2: 16 x-", tVal, true},
{"method on chained var",
"{{range .MSIone}}{{if $.U.TrueFalse $.True}}{{$.U.TrueFalse $.True}}{{else}}WRONG{{end}}{{end}}",
"true", tVal, true},
{"chained method",
"{{range .MSIone}}{{if $.GetU.TrueFalse $.True}}{{$.U.TrueFalse $.True}}{{else}}WRONG{{end}}{{end}}",
"true", tVal, true},
{"chained method on variable",
"{{with $x := .}}{{with .SI}}{{$.GetU.TrueFalse $.True}}{{end}}{{end}}",
"true", tVal, true},
// Pipelines.
{"pipeline", "-{{.Method0 | .Method2 .U16}}-", "-Method2: 16 M0-", tVal, true},
// If.
{"if true", "{{if true}}TRUE{{end}}", "TRUE", tVal, true},
{"if false", "{{if false}}TRUE{{else}}FALSE{{end}}", "FALSE", tVal, true},
{"if 1", "{{if 1}}NON-ZERO{{else}}ZERO{{end}}", "NON-ZERO", tVal, true},
{"if 0", "{{if 0}}NON-ZERO{{else}}ZERO{{end}}", "ZERO", tVal, true},
{"if 1.5", "{{if 1.5}}NON-ZERO{{else}}ZERO{{end}}", "NON-ZERO", tVal, true},
{"if 0.0", "{{if .FloatZero}}NON-ZERO{{else}}ZERO{{end}}", "ZERO", tVal, true},
{"if 1.5i", "{{if 1.5i}}NON-ZERO{{else}}ZERO{{end}}", "NON-ZERO", tVal, true},
{"if 0.0i", "{{if .ComplexZero}}NON-ZERO{{else}}ZERO{{end}}", "ZERO", tVal, true},
{"if emptystring", "{{if ``}}NON-EMPTY{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
{"if string", "{{if `notempty`}}NON-EMPTY{{else}}EMPTY{{end}}", "NON-EMPTY", tVal, true},
{"if emptyslice", "{{if .SIEmpty}}NON-EMPTY{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
{"if slice", "{{if .SI}}NON-EMPTY{{else}}EMPTY{{end}}", "NON-EMPTY", tVal, true},
{"if emptymap", "{{if .MSIEmpty}}NON-EMPTY{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
{"if map", "{{if .MSI}}NON-EMPTY{{else}}EMPTY{{end}}", "NON-EMPTY", tVal, true},
{"if $x with $y int", "{{if $x := true}}{{with $y := .I}}{{$x}},{{$y}}{{end}}{{end}}", "true,17", tVal, true},
{"if $x with $x int", "{{if $x := true}}{{with $x := .I}}{{$x}},{{end}}{{$x}}{{end}}", "17,true", tVal, true},
// Print etc.
{"print", `{{print "hello, print"}}`, "hello, print", tVal, true},
{"print", `{{print 1 2 3}}`, "1 2 3", tVal, true},
{"println", `{{println 1 2 3}}`, "1 2 3\n", tVal, true},
{"printf int", `{{printf "%04x" 127}}`, "007f", tVal, true},
{"printf float", `{{printf "%g" 3.5}}`, "3.5", tVal, true},
{"printf complex", `{{printf "%g" 1+7i}}`, "(1+7i)", tVal, true},
{"printf string", `{{printf "%s" "hello"}}`, "hello", tVal, true},
{"printf function", `{{printf "%#q" zeroArgs}}`, "`zeroArgs`", tVal, true},
{"printf field", `{{printf "%s" .U.V}}`, "v", tVal, true},
{"printf method", `{{printf "%s" .Method0}}`, "M0", tVal, true},
{"printf dot", `{{with .I}}{{printf "%d" .}}{{end}}`, "17", tVal, true},
{"printf var", `{{with $x := .I}}{{printf "%d" $x}}{{end}}`, "17", tVal, true},
{"printf lots", `{{printf "%d %s %g %s" 127 "hello" 7-3i .Method0}}`, "127 hello (7-3i) M0", tVal, true},
// HTML.
{"html", `{{html "<script>alert(\"XSS\");</script>"}}`,
"&lt;script&gt;alert(&#34;XSS&#34;);&lt;/script&gt;", nil, true},
{"html pipeline", `{{printf "<script>alert(\"XSS\");</script>" | html}}`,
"&lt;script&gt;alert(&#34;XSS&#34;);&lt;/script&gt;", nil, true},
// JavaScript.
{"js", `{{js .}}`, `It\'d be nice.`, `It'd be nice.`, true},
// URL query.
{"urlquery", `{{""|urlquery}}`, "", nil, true},
// Booleans
{"not", "{{not true}} {{not false}}", "false true", nil, true},
{"and", "{{and false 0}} {{and 1 0}} {{and 0 true}} {{and 1 1}}", "false 0 0 1", nil, true},
{"or", "{{or 0 0}} {{or 1 0}} {{or 0 true}} {{or 1 1}}", "0 1 true 1", nil, true},
{"boolean if", "{{if and true 1 `hi`}}TRUE{{else}}FALSE{{end}}", "TRUE", tVal, true},
{"boolean if not", "{{if and true 1 `hi` | not}}TRUE{{else}}FALSE{{end}}", "FALSE", nil, true},
// Indexing.
{"slice[0]", "{{index .SI 0}}", "3", tVal, true},
{"slice[1]", "{{index .SI 1}}", "4", tVal, true},
{"slice[HUGE]", "{{index .SI 10}}", "", tVal, false},
{"slice[WRONG]", "{{index .SI `hello`}}", "", tVal, false},
{"map[one]", "{{index .MSI `one`}}", "1", tVal, true},
{"map[two]", "{{index .MSI `two`}}", "2", tVal, true},
{"map[NO]", "{{index .MSI `XXX`}}", "", tVal, true},
{"map[WRONG]", "{{index .MSI 10}}", "", tVal, false},
{"double index", "{{index .SMSI 1 `eleven`}}", "11", tVal, true},
// Len.
{"slice", "{{len .SI}}", "3", tVal, true},
{"map", "{{len .MSI }}", "3", tVal, true},
{"len of int", "{{len 3}}", "", tVal, false},
{"len of nothing", "{{len .Empty0}}", "", tVal, false},
// With.
{"with true", "{{with true}}{{.}}{{end}}", "true", tVal, true},
{"with false", "{{with false}}{{.}}{{else}}FALSE{{end}}", "FALSE", tVal, true},
{"with 1", "{{with 1}}{{.}}{{else}}ZERO{{end}}", "1", tVal, true},
{"with 0", "{{with 0}}{{.}}{{else}}ZERO{{end}}", "ZERO", tVal, true},
{"with 1.5", "{{with 1.5}}{{.}}{{else}}ZERO{{end}}", "1.5", tVal, true},
{"with 0.0", "{{with .FloatZero}}{{.}}{{else}}ZERO{{end}}", "ZERO", tVal, true},
{"with 1.5i", "{{with 1.5i}}{{.}}{{else}}ZERO{{end}}", "(0+1.5i)", tVal, true},
{"with 0.0i", "{{with .ComplexZero}}{{.}}{{else}}ZERO{{end}}", "ZERO", tVal, true},
{"with emptystring", "{{with ``}}{{.}}{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
{"with string", "{{with `notempty`}}{{.}}{{else}}EMPTY{{end}}", "notempty", tVal, true},
{"with emptyslice", "{{with .SIEmpty}}{{.}}{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
{"with slice", "{{with .SI}}{{.}}{{else}}EMPTY{{end}}", "[3 4 5]", tVal, true},
{"with emptymap", "{{with .MSIEmpty}}{{.}}{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
{"with map", "{{with .MSIone}}{{.}}{{else}}EMPTY{{end}}", "map[one:1]", tVal, true},
{"with empty interface, struct field", "{{with .Empty4}}{{.V}}{{end}}", "UinEmpty", tVal, true},
{"with $x int", "{{with $x := .I}}{{$x}}{{end}}", "17", tVal, true},
{"with $x struct.U.V", "{{with $x := $}}{{$x.U.V}}{{end}}", "v", tVal, true},
{"with variable and action", "{{with $x := $}}{{$y := $.U.V}}{{$y}}{{end}}", "v", tVal, true},
// Range.
{"range []int", "{{range .SI}}-{{.}}-{{end}}", "-3--4--5-", tVal, true},
{"range empty no else", "{{range .SIEmpty}}-{{.}}-{{end}}", "", tVal, true},
{"range []int else", "{{range .SI}}-{{.}}-{{else}}EMPTY{{end}}", "-3--4--5-", tVal, true},
{"range empty else", "{{range .SIEmpty}}-{{.}}-{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
{"range []bool", "{{range .SB}}-{{.}}-{{end}}", "-true--false-", tVal, true},
{"range []int method", "{{range .SI | .MAdd .I}}-{{.}}-{{end}}", "-20--21--22-", tVal, true},
{"range map", "{{range .MSI | .MSort}}-{{.}}-{{end}}", "-one--three--two-", tVal, true},
{"range empty map no else", "{{range .MSIEmpty}}-{{.}}-{{end}}", "", tVal, true},
{"range map else", "{{range .MSI | .MSort}}-{{.}}-{{else}}EMPTY{{end}}", "-one--three--two-", tVal, true},
{"range empty map else", "{{range .MSIEmpty}}-{{.}}-{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
{"range empty interface", "{{range .Empty3}}-{{.}}-{{else}}EMPTY{{end}}", "-7--8-", tVal, true},
{"range empty nil", "{{range .Empty0}}-{{.}}-{{end}}", "", tVal, true},
{"range $x SI", "{{range $x := .SI}}<{{$x}}>{{end}}", "<3><4><5>", tVal, true},
{"range $x $y SI", "{{range $x, $y := .SI}}<{{$x}}={{$y}}>{{end}}", "<0=3><1=4><2=5>", tVal, true},
{"range $x MSIone", "{{range $x := .MSIone}}<{{$x}}>{{end}}", "<1>", tVal, true},
{"range $x $y MSIone", "{{range $x, $y := .MSIone}}<{{$x}}={{$y}}>{{end}}", "<one=1>", tVal, true},
{"range $x PSI", "{{range $x := .PSI}}<{{$x}}>{{end}}", "<21><22><23>", tVal, true},
{"declare in range", "{{range $x := .PSI}}<{{$foo:=$x}}{{$x}}>{{end}}", "<21><22><23>", tVal, true},
{"range count", `{{range $i, $x := count 5}}[{{$i}}]{{$x}}{{end}}`, "[0]a[1]b[2]c[3]d[4]e", tVal, true},
{"range nil count", `{{range $i, $x := count 0}}{{else}}empty{{end}}`, "empty", tVal, true},
// Cute examples.
{"or as if true", `{{or .SI "slice is empty"}}`, "[3 4 5]", tVal, true},
{"or as if false", `{{or .SIEmpty "slice is empty"}}`, "slice is empty", tVal, true},
// Error handling.
{"error method, error", "{{.EPERM true}}", "", tVal, false},
{"error method, no error", "{{.EPERM false}}", "false", tVal, true},
// Fixed bugs.
// Must separate dot and receiver; otherwise args are evaluated with dot set to variable.
{"bug0", "{{range .MSIone}}{{if $.Method1 .}}X{{end}}{{end}}", "X", tVal, true},
// Do not loop endlessly in indirect for non-empty interfaces.
// The bug appears with *interface only; looped forever.
{"bug1", "{{.Method0}}", "M0", &iVal, true},
// Was taking address of interface field, so method set was empty.
{"bug2", "{{$.NonEmptyInterface.Method0}}", "M0", tVal, true},
// Struct values were not legal in with - mere oversight.
{"bug3", "{{with $}}{{.Method0}}{{end}}", "M0", tVal, true},
// Nil interface values in if.
{"bug4", "{{if .Empty0}}non-nil{{else}}nil{{end}}", "nil", tVal, true},
// Stringer.
{"bug5", "{{.Str}}", "foozle", tVal, true},
// Args need to be indirected and dereferenced sometimes.
{"bug6a", "{{vfunc .V0 .V1}}", "vfunc", tVal, true},
{"bug6b", "{{vfunc .V0 .V0}}", "vfunc", tVal, true},
{"bug6c", "{{vfunc .V1 .V0}}", "vfunc", tVal, true},
{"bug6d", "{{vfunc .V1 .V1}}", "vfunc", tVal, true},
func zeroArgs() string {
return "zeroArgs"
func oneArg(a string) string {
return "oneArg=" + a
// count returns a channel that will deliver n sequential 1-letter strings starting at "a"
func count(n int) chan string {
if n == 0 {
return nil
c := make(chan string)
go func() {
for i := 0; i < n; i++ {
c <- "abcdefghijklmnop"[i : i+1]
return c
// vfunc takes a *V and a V
func vfunc(V, *V) string {
return "vfunc"
func testExecute(execTests []execTest, set *Set, t *testing.T) {
b := new(bytes.Buffer)
funcs := FuncMap{
"count": count,
"oneArg": oneArg,
"typeOf": typeOf,
"vfunc": vfunc,
"zeroArgs": zeroArgs,
for _, test := range execTests {
tmpl := New(
_, err := tmpl.ParseInSet(test.input, set)
if err != nil {
t.Errorf("%s: parse error: %s",, err)
err = tmpl.Execute(b,
switch {
case !test.ok && err == nil:
t.Errorf("%s: expected error; got none",
case test.ok && err != nil:
t.Errorf("%s: unexpected execute error: %s",, err)
case !test.ok && err != nil:
// expected error, got one
if *debug {
fmt.Printf("%s: %s\n\t%s\n",, test.input, err)
result := b.String()
if result != test.output {
t.Errorf("%s: expected\n\t%q\ngot\n\t%q",, test.output, result)
func TestExecute(t *testing.T) {
testExecute(execTests, nil, t)
// Check that an error from a method flows back to the top.
func TestExecuteError(t *testing.T) {
b := new(bytes.Buffer)
tmpl := New("error")
_, err := tmpl.Parse("{{.EPERM true}}")
if err != nil {
t.Fatalf("parse error: %s", err)
err = tmpl.Execute(b, tVal)
if err == nil {
t.Errorf("expected error; got none")
} else if !strings.Contains(err.String(), os.EPERM.String()) {
if *debug {
fmt.Printf("test execute error: %s\n", err)
t.Errorf("expected os.EPERM; got %s", err)
func TestJSEscaping(t *testing.T) {
testCases := []struct {
in, exp string
{`a`, `a`},
{`'foo`, `\'foo`},
{`Go "jump" \`, `Go \"jump\" \\`},
{`Yukihiro says "今日は世界"`, `Yukihiro says \"今日は世界\"`},
{"unprintable \uFDFF", `unprintable \uFDFF`},
{`<html>`, `\x3Chtml\x3E`},
for _, tc := range testCases {
s := JSEscapeString(
if s != tc.exp {
t.Errorf("JS escaping [%s] got [%s] want [%s]",, s, tc.exp)
// A nice example: walk a binary tree.
type Tree struct {
Val int
Left, Right *Tree
const treeTemplate = `
{{define "tree"}}
{{with .Left}}
{{template "tree" .}}
{{with .Right}}
{{template "tree" .}}
func TestTree(t *testing.T) {
var tree = &Tree{
2, &Tree{
4, nil, nil,
6, nil, nil,
9, nil, nil,
11, nil, nil,
set := new(Set)
_, err := set.Parse(treeTemplate)
if err != nil {
t.Fatal("parse error:", err)
var b bytes.Buffer
err = set.Execute(&b, "tree", tree)
if err != nil {
t.Fatal("exec error:", err)
stripSpace := func(r int) int {
if r == '\t' || r == '\n' {
return -1
return r
result := strings.Map(stripSpace, b.String())
const expect = "[1[2[3[4]][5[6]]][7[8[9]][10[11]]]]"
if result != expect {
t.Errorf("expected %q got %q", expect, result)