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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<<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},

        // 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}}", "<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},
        {".Method3(nil)", "-{{.Method3 .MXI.unset}}-", "-Method3: <nil>-", 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>"}}`,
                "&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}}-{{.}}-{{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}}", "<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},
        {"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`},
                {`<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,
                        },
                },
        }
        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)
        }
}