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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 (

        "bytes"

        "errors"

        "flag"

        "fmt"

        "os"

        "reflect"

        "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

        // Struct with Error method.

        W0     W

        W1, W2 *W

        // 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

        Err error

        // 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)

}

type W struct {

        k int

}

func (w *W) Error() string {

        if w == nil {

                return "nilW"

        }

        return fmt.Sprintf("[%d]", w.k)

}

var tVal = &T{

        True:   true,

        I:      17,

        U16:    16,

        X:      "x",

        U:      &U{"v"},

        V0:     V{6666},

        V1:     &V{7777}, // leave V2 as nil

        W0:     W{888},

        W1:     &W{999}, // leave W2 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")),

        Err:               errors.New("erroozle"),

        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) Method3(v interface{}) string {

        return fmt.Sprintf("Method3: %v", v)

}

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

}

// EPERM returns a value and an error according to its argument.

func (t *T) EPERM(error bool) (bool, 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<

        bigUint = fmt.Sprintf("0x%x", uint(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}}", "", 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},

        {"dot complex", "<{{.}}>", "<(16.2-17i)>", 16.2 - 17i, true},

        {"dot string", "<{{.}}>", "", "hello", true},

        {"dot slice", "<{{.}}>", "<[-1 -2 -3]>", []int{-1, -2, -3}, true},

        {"dot map", "<{{.}}>", "", 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},

        // Type with Error method.

        {"W{888}.Error()", "-{{.W0}}-", "-[888]-", tVal, true},

        {"&W{999}.Error()", "-{{.W1}}-", "-[999]-", tVal, true},

        {"(*W)(nil).Error()", "-{{.W2}}-", "-nilW-", 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}}", "", tVal, true},

        // Empty interfaces holding values.

        {"empty nil", "{{.Empty0}}", "", 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},

        {".Method3(nil)", "-{{.Method3 .MXI.unset}}-", "-Method3: -", 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 map unset", "{{if .MXI.none}}NON-ZERO{{else}}ZERO{{end}}", "ZERO", tVal, true},

        {"if map not unset", "{{if not .MXI.none}}ZERO{{else}}NON-ZERO{{end}}", "ZERO", 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>", nil, true},

        {"html pipeline", `{{printf "" | 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}}-{{.}}-{{end}}", "-1--3--2-", tVal, true},

        {"range empty map no else", "{{range .MSIEmpty}}-{{.}}-{{end}}", "", tVal, true},

        {"range map else", "{{range .MSI}}-{{.}}-{{else}}EMPTY{{end}}", "-1--3--2-", 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}}", "", 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},

        {"bug5a", "{{.Err}}", "erroozle", 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, template *Template, t *testing.T) {

        b := new(bytes.Buffer)

        funcs := FuncMap{

                "count":    count,

                "oneArg":   oneArg,

                "typeOf":   typeOf,

                "vfunc":    vfunc,

                "zeroArgs": zeroArgs,

        }

        for _, test := range execTests {

                var tmpl *Template

                var err error

                if template == nil {

                        tmpl, err = New(test.name).Funcs(funcs).Parse(test.input)

                } else {

                        tmpl, err = template.New(test.name).Funcs(funcs).Parse(test.input)

                }

                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.Error(), os.EPERM.Error()) {

                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`},

                {``, `\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,

                        },

                },

        }

        tmpl, err := New("root").Delims("(", ")").Parse(treeTemplate)

        if err != nil {

                t.Fatal("parse error:", err)

        }

        var b bytes.Buffer

        stripSpace := func(r rune) rune {

                if r == '\t' || r == '\n' {

                        return -1

                }

                return r

        }

        const expect = "[1[2[3[4]][5[6]]][7[8[9]][10[11]]]]"

        // First by looking up the template.

        err = tmpl.Lookup("tree").Execute(&b, tree)

        if err != nil {

                t.Fatal("exec error:", err)

        }

        result := strings.Map(stripSpace, b.String())

        if result != expect {

                t.Errorf("expected %q got %q", expect, result)

        }

        // Then direct to execution.

        b.Reset()

        err = tmpl.ExecuteTemplate(&b, "tree", tree)

        if err != nil {

                t.Fatal("exec error:", err)

        }

        result = strings.Map(stripSpace, b.String())

        if result != expect {

                t.Errorf("expected %q got %q", expect, result)

        }

}