src/pkg/template/exec_test.go - go - Git at Google

 // 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 (
 	"bytes"
 	"flag"
 	"fmt"
 	"os"
 	"reflect"
 	"sort"
 	"strings"
 	"testing"
 )

 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:               bytes.NewBuffer([]byte("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) *[]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
 		i++
 	}
 	sort.Strings(keys)
 	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", "{{.MSI.one}}", "1", tVal, true},
 	{"map .two", "{{.MSI.two}}", "2", tVal, true},
 	{"map .NO", "{{.MSI.NO}}", "<no value>", tVal, true},
 	{"map .one interface", "{{.MXI.one}}", "1", tVal, true},
 	{"map .WRONG args", "{{.MSI.one 1}}", "", tVal, false},
 	{"map .WRONG type", "{{.MII.one}}", "", 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]>", map[string]int{"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", `{{"http://www.example.org/"|urlquery}}`, "http%3A%2F%2Fwww.example.org%2F", 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]
 		}
 		close(c)
 	}()
 	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(test.name).Funcs(funcs)
 		_, err := tmpl.ParseInSet(test.input, set)
 		if err != nil {
 			t.Errorf("%s: parse error: %s", test.name, err)
 			continue
 		}
 		b.Reset()
 		err = tmpl.Execute(b, test.data)
 		switch {
 		case !test.ok && err == nil:
 			t.Errorf("%s: expected error; got none", test.name)
 			continue
 		case test.ok && err != nil:
 			t.Errorf("%s: unexpected execute error: %s", test.name, err)
 			continue
 		case !test.ok && err != nil:
 			// expected error, got one
 			if *debug {
 				fmt.Printf("%s: %s\n\t%s\n", test.name, test.input, err)
 			}
 		}
 		result := b.String()
 		if result != test.output {
 			t.Errorf("%s: expected\n\t%q\ngot\n\t%q", test.name, test.output, result)
 		}
 	}
 }

 func TestExecute(t *testing.T) {
 	testExecute(execTests, nil, t)
 }

 var delimPairs = []string{
 	"", "", // default
 	"{{", "}}", // same as default
 	"<<", ">>", // distinct
 	"|", "|", // same
 	"(日)", "(本)", // peculiar
 }

 func TestDelims(t *testing.T) {
 	const hello = "Hello, world"
 	var value = struct{ Str string }{hello}
 	for i := 0; i < len(delimPairs); i += 2 {
 		text := ".Str"
 		left := delimPairs[i+0]
 		trueLeft := left
 		right := delimPairs[i+1]
 		trueRight := right
 		if left == "" { // default case
 			trueLeft = "{{"
 		}
 		if right == "" { // default case
 			trueRight = "}}"
 		}
 		text = trueLeft + text + trueRight
 		// Now add a comment
 		text += trueLeft + "/*comment*/" + trueRight
 		// Now add  an action containing a string.
 		text += trueLeft + `"` + trueLeft + `"` + trueRight
 		// At this point text looks like `{{.Str}}{{/*comment*/}}{{"{{"}}`.
 		tmpl, err := New("delims").Delims(left, right).Parse(text)
 		if err != nil {
 			t.Fatalf("delim %q text %q parse err %s", left, text, err)
 		}
 		var b = new(bytes.Buffer)
 		err = tmpl.Execute(b, value)
 		if err != nil {
 			t.Fatalf("delim %q exec err %s", left, err)
 		}
 		if b.String() != hello+trueLeft {
 			t.Errorf("expected %q got %q", hello+trueLeft, b.String())
 		}
 	}
 }

 // 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(tc.in)
 		if s != tc.exp {
 			t.Errorf("JS escaping [%s] got [%s] want [%s]", tc.in, s, tc.exp)
 		}
 	}
 }

 // A nice example: walk a binary tree.

 type Tree struct {
 	Val         int
 	Left, Right *Tree
 }

 // Use different delimiters to test Set.Delims.
 const treeTemplate = `
 	(define "tree")
 	[
 		(.Val)
 		(with .Left)
 			(template "tree" .)
 		(end)
 		(with .Right)
 			(template "tree" .)
 		(end)
 	]
 	(end)
 `

 func TestTree(t *testing.T) {
 	var tree = &Tree{
 		1,
 		&Tree{
 			2, &Tree{
 				3,
 				&Tree{
 					4, nil, nil,
 				},
 				nil,
 			},
 			&Tree{
 				5,
 				&Tree{
 					6, nil, nil,
 				},
 				nil,
 			},
 		},
 		&Tree{
 			7,
 			&Tree{
 				8,
 				&Tree{
 					9, nil, nil,
 				},
 				nil,
 			},
 			&Tree{
 				10,
 				&Tree{
 					11, nil, nil,
 				},
 				nil,
 			},
 		},
 	}
 	set := new(Set)
 	_, err := set.Delims("(", ")").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 rune) rune {
 		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)
 	}
 }
	// 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 (
	"bytes"
	"flag"
	"fmt"
	"os"
	"reflect"
	"sort"
	"strings"
	"testing"
	)

	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: bytes.NewBuffer([]byte("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) *[]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
	i++
	}
	sort.Strings(keys)
	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", "{{.MSI.one}}", "1", tVal, true},
	{"map .two", "{{.MSI.two}}", "2", tVal, true},
	{"map .NO", "{{.MSI.NO}}", "<no value>", tVal, true},
	{"map .one interface", "{{.MXI.one}}", "1", tVal, true},
	{"map .WRONG args", "{{.MSI.one 1}}", "", tVal, false},
	{"map .WRONG type", "{{.MII.one}}", "", 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]>", map[string]int{"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>"}}`,
	"<script>alert("XSS");</script>", nil, true},
	{"html pipeline", `{{printf "<script>alert(\"XSS\");</script>" \| html}}`,
	"<script>alert("XSS");</script>", nil, true},

	// JavaScript.
	{"js", `{{js .}}`, `It\'d be nice.`, `It'd be nice.`, true},

	// URL query.
	{"urlquery", `{{"http://www.example.org/"\|urlquery}}`, "http%3A%2F%2Fwww.example.org%2F", 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]
	}
	close(c)
	}()
	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(test.name).Funcs(funcs)
	_, err := tmpl.ParseInSet(test.input, set)
	if err != nil {
	t.Errorf("%s: parse error: %s", test.name, err)
	continue
	}
	b.Reset()
	err = tmpl.Execute(b, test.data)
	switch {
	case !test.ok && err == nil:
	t.Errorf("%s: expected error; got none", test.name)
	continue
	case test.ok && err != nil:
	t.Errorf("%s: unexpected execute error: %s", test.name, err)
	continue
	case !test.ok && err != nil:
	// expected error, got one
	if *debug {
	fmt.Printf("%s: %s\n\t%s\n", test.name, test.input, err)
	}
	}
	result := b.String()
	if result != test.output {
	t.Errorf("%s: expected\n\t%q\ngot\n\t%q", test.name, test.output, result)
	}
	}
	}

	func TestExecute(t *testing.T) {
	testExecute(execTests, nil, t)
	}

	var delimPairs = []string{
	"", "", // default
	"{{", "}}", // same as default
	"<<", ">>", // distinct
	"\|", "\|", // same
	"(日)", "(本)", // peculiar
	}

	func TestDelims(t *testing.T) {
	const hello = "Hello, world"
	var value = struct{ Str string }{hello}
	for i := 0; i < len(delimPairs); i += 2 {
	text := ".Str"
	left := delimPairs[i+0]
	trueLeft := left
	right := delimPairs[i+1]
	trueRight := right
	if left == "" { // default case
	trueLeft = "{{"
	}
	if right == "" { // default case
	trueRight = "}}"
	}
	text = trueLeft + text + trueRight
	// Now add a comment
	text += trueLeft + "/comment/" + trueRight
	// Now add an action containing a string.
	text += trueLeft + `"` + trueLeft + `"` + trueRight
	// At this point text looks like `{{.Str}}{{/comment/}}{{"{{"}}`.
	tmpl, err := New("delims").Delims(left, right).Parse(text)
	if err != nil {
	t.Fatalf("delim %q text %q parse err %s", left, text, err)
	}
	var b = new(bytes.Buffer)
	err = tmpl.Execute(b, value)
	if err != nil {
	t.Fatalf("delim %q exec err %s", left, err)
	}
	if b.String() != hello+trueLeft {
	t.Errorf("expected %q got %q", hello+trueLeft, b.String())
	}
	}
	}

	// 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(tc.in)
	if s != tc.exp {
	t.Errorf("JS escaping [%s] got [%s] want [%s]", tc.in, s, tc.exp)
	}
	}
	}

	// A nice example: walk a binary tree.

	type Tree struct {
	Val int
	Left, Right *Tree
	}

	// Use different delimiters to test Set.Delims.
	const treeTemplate = `
	(define "tree")
	[
	(.Val)
	(with .Left)
	(template "tree" .)
	(end)
	(with .Right)
	(template "tree" .)
	(end)
	]
	(end)
	`

	func TestTree(t *testing.T) {
	var tree = &Tree{
	1,
	&Tree{
	2, &Tree{
	3,
	&Tree{
	4, nil, nil,
	},
	nil,
	},
	&Tree{
	5,
	&Tree{
	6, nil, nil,
	},
	nil,
	},
	},
	&Tree{
	7,
	&Tree{
	8,
	&Tree{
	9, nil, nil,
	},
	nil,
	},
	&Tree{
	10,
	&Tree{
	11, nil, nil,
	},
	nil,
	},
	},
	}
	set := new(Set)
	_, err := set.Delims("(", ")").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 rune) rune {
	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)
	}
	}