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Source file src/text/template/exec_test.go

Documentation: text/template

     1  // Copyright 2011 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package template
     6  
     7  import (
     8  	"bytes"
     9  	"errors"
    10  	"flag"
    11  	"fmt"
    12  	"io/ioutil"
    13  	"reflect"
    14  	"strings"
    15  	"testing"
    16  )
    17  
    18  var debug = flag.Bool("debug", false, "show the errors produced by the tests")
    19  
    20  // T has lots of interesting pieces to use to test execution.
    21  type T struct {
    22  	// Basics
    23  	True        bool
    24  	I           int
    25  	U16         uint16
    26  	X           string
    27  	FloatZero   float64
    28  	ComplexZero complex128
    29  	// Nested structs.
    30  	U *U
    31  	// Struct with String method.
    32  	V0     V
    33  	V1, V2 *V
    34  	// Struct with Error method.
    35  	W0     W
    36  	W1, W2 *W
    37  	// Slices
    38  	SI      []int
    39  	SIEmpty []int
    40  	SB      []bool
    41  	// Maps
    42  	MSI      map[string]int
    43  	MSIone   map[string]int // one element, for deterministic output
    44  	MSIEmpty map[string]int
    45  	MXI      map[interface{}]int
    46  	MII      map[int]int
    47  	MI32S    map[int32]string
    48  	MI64S    map[int64]string
    49  	MUI32S   map[uint32]string
    50  	MUI64S   map[uint64]string
    51  	MI8S     map[int8]string
    52  	MUI8S    map[uint8]string
    53  	SMSI     []map[string]int
    54  	// Empty interfaces; used to see if we can dig inside one.
    55  	Empty0 interface{} // nil
    56  	Empty1 interface{}
    57  	Empty2 interface{}
    58  	Empty3 interface{}
    59  	Empty4 interface{}
    60  	// Non-empty interfaces.
    61  	NonEmptyInterface         I
    62  	NonEmptyInterfacePtS      *I
    63  	NonEmptyInterfaceNil      I
    64  	NonEmptyInterfaceTypedNil I
    65  	// Stringer.
    66  	Str fmt.Stringer
    67  	Err error
    68  	// Pointers
    69  	PI  *int
    70  	PS  *string
    71  	PSI *[]int
    72  	NIL *int
    73  	// Function (not method)
    74  	BinaryFunc      func(string, string) string
    75  	VariadicFunc    func(...string) string
    76  	VariadicFuncInt func(int, ...string) string
    77  	NilOKFunc       func(*int) bool
    78  	ErrFunc         func() (string, error)
    79  	PanicFunc       func() string
    80  	// Template to test evaluation of templates.
    81  	Tmpl *Template
    82  	// Unexported field; cannot be accessed by template.
    83  	unexported int
    84  }
    85  
    86  type S []string
    87  
    88  func (S) Method0() string {
    89  	return "M0"
    90  }
    91  
    92  type U struct {
    93  	V string
    94  }
    95  
    96  type V struct {
    97  	j int
    98  }
    99  
   100  func (v *V) String() string {
   101  	if v == nil {
   102  		return "nilV"
   103  	}
   104  	return fmt.Sprintf("<%d>", v.j)
   105  }
   106  
   107  type W struct {
   108  	k int
   109  }
   110  
   111  func (w *W) Error() string {
   112  	if w == nil {
   113  		return "nilW"
   114  	}
   115  	return fmt.Sprintf("[%d]", w.k)
   116  }
   117  
   118  var siVal = I(S{"a", "b"})
   119  
   120  var tVal = &T{
   121  	True:   true,
   122  	I:      17,
   123  	U16:    16,
   124  	X:      "x",
   125  	U:      &U{"v"},
   126  	V0:     V{6666},
   127  	V1:     &V{7777}, // leave V2 as nil
   128  	W0:     W{888},
   129  	W1:     &W{999}, // leave W2 as nil
   130  	SI:     []int{3, 4, 5},
   131  	SB:     []bool{true, false},
   132  	MSI:    map[string]int{"one": 1, "two": 2, "three": 3},
   133  	MSIone: map[string]int{"one": 1},
   134  	MXI:    map[interface{}]int{"one": 1},
   135  	MII:    map[int]int{1: 1},
   136  	MI32S:  map[int32]string{1: "one", 2: "two"},
   137  	MI64S:  map[int64]string{2: "i642", 3: "i643"},
   138  	MUI32S: map[uint32]string{2: "u322", 3: "u323"},
   139  	MUI64S: map[uint64]string{2: "ui642", 3: "ui643"},
   140  	MI8S:   map[int8]string{2: "i82", 3: "i83"},
   141  	MUI8S:  map[uint8]string{2: "u82", 3: "u83"},
   142  	SMSI: []map[string]int{
   143  		{"one": 1, "two": 2},
   144  		{"eleven": 11, "twelve": 12},
   145  	},
   146  	Empty1:                    3,
   147  	Empty2:                    "empty2",
   148  	Empty3:                    []int{7, 8},
   149  	Empty4:                    &U{"UinEmpty"},
   150  	NonEmptyInterface:         &T{X: "x"},
   151  	NonEmptyInterfacePtS:      &siVal,
   152  	NonEmptyInterfaceTypedNil: (*T)(nil),
   153  	Str:                       bytes.NewBuffer([]byte("foozle")),
   154  	Err:                       errors.New("erroozle"),
   155  	PI:                        newInt(23),
   156  	PS:                        newString("a string"),
   157  	PSI:                       newIntSlice(21, 22, 23),
   158  	BinaryFunc:                func(a, b string) string { return fmt.Sprintf("[%s=%s]", a, b) },
   159  	VariadicFunc:              func(s ...string) string { return fmt.Sprint("<", strings.Join(s, "+"), ">") },
   160  	VariadicFuncInt:           func(a int, s ...string) string { return fmt.Sprint(a, "=<", strings.Join(s, "+"), ">") },
   161  	NilOKFunc:                 func(s *int) bool { return s == nil },
   162  	ErrFunc:                   func() (string, error) { return "bla", nil },
   163  	PanicFunc:                 func() string { panic("test panic") },
   164  	Tmpl:                      Must(New("x").Parse("test template")), // "x" is the value of .X
   165  }
   166  
   167  var tSliceOfNil = []*T{nil}
   168  
   169  // A non-empty interface.
   170  type I interface {
   171  	Method0() string
   172  }
   173  
   174  var iVal I = tVal
   175  
   176  // Helpers for creation.
   177  func newInt(n int) *int {
   178  	return &n
   179  }
   180  
   181  func newString(s string) *string {
   182  	return &s
   183  }
   184  
   185  func newIntSlice(n ...int) *[]int {
   186  	p := new([]int)
   187  	*p = make([]int, len(n))
   188  	copy(*p, n)
   189  	return p
   190  }
   191  
   192  // Simple methods with and without arguments.
   193  func (t *T) Method0() string {
   194  	return "M0"
   195  }
   196  
   197  func (t *T) Method1(a int) int {
   198  	return a
   199  }
   200  
   201  func (t *T) Method2(a uint16, b string) string {
   202  	return fmt.Sprintf("Method2: %d %s", a, b)
   203  }
   204  
   205  func (t *T) Method3(v interface{}) string {
   206  	return fmt.Sprintf("Method3: %v", v)
   207  }
   208  
   209  func (t *T) Copy() *T {
   210  	n := new(T)
   211  	*n = *t
   212  	return n
   213  }
   214  
   215  func (t *T) MAdd(a int, b []int) []int {
   216  	v := make([]int, len(b))
   217  	for i, x := range b {
   218  		v[i] = x + a
   219  	}
   220  	return v
   221  }
   222  
   223  var myError = errors.New("my error")
   224  
   225  // MyError returns a value and an error according to its argument.
   226  func (t *T) MyError(error bool) (bool, error) {
   227  	if error {
   228  		return true, myError
   229  	}
   230  	return false, nil
   231  }
   232  
   233  // A few methods to test chaining.
   234  func (t *T) GetU() *U {
   235  	return t.U
   236  }
   237  
   238  func (u *U) TrueFalse(b bool) string {
   239  	if b {
   240  		return "true"
   241  	}
   242  	return ""
   243  }
   244  
   245  func typeOf(arg interface{}) string {
   246  	return fmt.Sprintf("%T", arg)
   247  }
   248  
   249  type execTest struct {
   250  	name   string
   251  	input  string
   252  	output string
   253  	data   interface{}
   254  	ok     bool
   255  }
   256  
   257  // bigInt and bigUint are hex string representing numbers either side
   258  // of the max int boundary.
   259  // We do it this way so the test doesn't depend on ints being 32 bits.
   260  var (
   261  	bigInt  = fmt.Sprintf("0x%x", int(1<<uint(reflect.TypeOf(0).Bits()-1)-1))
   262  	bigUint = fmt.Sprintf("0x%x", uint(1<<uint(reflect.TypeOf(0).Bits()-1)))
   263  )
   264  
   265  var execTests = []execTest{
   266  	// Trivial cases.
   267  	{"empty", "", "", nil, true},
   268  	{"text", "some text", "some text", nil, true},
   269  	{"nil action", "{{nil}}", "", nil, false},
   270  
   271  	// Ideal constants.
   272  	{"ideal int", "{{typeOf 3}}", "int", 0, true},
   273  	{"ideal float", "{{typeOf 1.0}}", "float64", 0, true},
   274  	{"ideal exp float", "{{typeOf 1e1}}", "float64", 0, true},
   275  	{"ideal complex", "{{typeOf 1i}}", "complex128", 0, true},
   276  	{"ideal int", "{{typeOf " + bigInt + "}}", "int", 0, true},
   277  	{"ideal too big", "{{typeOf " + bigUint + "}}", "", 0, false},
   278  	{"ideal nil without type", "{{nil}}", "", 0, false},
   279  
   280  	// Fields of structs.
   281  	{".X", "-{{.X}}-", "-x-", tVal, true},
   282  	{".U.V", "-{{.U.V}}-", "-v-", tVal, true},
   283  	{".unexported", "{{.unexported}}", "", tVal, false},
   284  
   285  	// Fields on maps.
   286  	{"map .one", "{{.MSI.one}}", "1", tVal, true},
   287  	{"map .two", "{{.MSI.two}}", "2", tVal, true},
   288  	{"map .NO", "{{.MSI.NO}}", "<no value>", tVal, true},
   289  	{"map .one interface", "{{.MXI.one}}", "1", tVal, true},
   290  	{"map .WRONG args", "{{.MSI.one 1}}", "", tVal, false},
   291  	{"map .WRONG type", "{{.MII.one}}", "", tVal, false},
   292  
   293  	// Dots of all kinds to test basic evaluation.
   294  	{"dot int", "<{{.}}>", "<13>", 13, true},
   295  	{"dot uint", "<{{.}}>", "<14>", uint(14), true},
   296  	{"dot float", "<{{.}}>", "<15.1>", 15.1, true},
   297  	{"dot bool", "<{{.}}>", "<true>", true, true},
   298  	{"dot complex", "<{{.}}>", "<(16.2-17i)>", 16.2 - 17i, true},
   299  	{"dot string", "<{{.}}>", "<hello>", "hello", true},
   300  	{"dot slice", "<{{.}}>", "<[-1 -2 -3]>", []int{-1, -2, -3}, true},
   301  	{"dot map", "<{{.}}>", "<map[two:22]>", map[string]int{"two": 22}, true},
   302  	{"dot struct", "<{{.}}>", "<{7 seven}>", struct {
   303  		a int
   304  		b string
   305  	}{7, "seven"}, true},
   306  
   307  	// Variables.
   308  	{"$ int", "{{$}}", "123", 123, true},
   309  	{"$.I", "{{$.I}}", "17", tVal, true},
   310  	{"$.U.V", "{{$.U.V}}", "v", tVal, true},
   311  	{"declare in action", "{{$x := $.U.V}}{{$x}}", "v", tVal, true},
   312  	{"simple assignment", "{{$x := 2}}{{$x = 3}}{{$x}}", "3", tVal, true},
   313  	{"nested assignment",
   314  		"{{$x := 2}}{{if true}}{{$x = 3}}{{end}}{{$x}}",
   315  		"3", tVal, true},
   316  	{"nested assignment changes the last declaration",
   317  		"{{$x := 1}}{{if true}}{{$x := 2}}{{if true}}{{$x = 3}}{{end}}{{end}}{{$x}}",
   318  		"1", tVal, true},
   319  
   320  	// Type with String method.
   321  	{"V{6666}.String()", "-{{.V0}}-", "-<6666>-", tVal, true},
   322  	{"&V{7777}.String()", "-{{.V1}}-", "-<7777>-", tVal, true},
   323  	{"(*V)(nil).String()", "-{{.V2}}-", "-nilV-", tVal, true},
   324  
   325  	// Type with Error method.
   326  	{"W{888}.Error()", "-{{.W0}}-", "-[888]-", tVal, true},
   327  	{"&W{999}.Error()", "-{{.W1}}-", "-[999]-", tVal, true},
   328  	{"(*W)(nil).Error()", "-{{.W2}}-", "-nilW-", tVal, true},
   329  
   330  	// Pointers.
   331  	{"*int", "{{.PI}}", "23", tVal, true},
   332  	{"*string", "{{.PS}}", "a string", tVal, true},
   333  	{"*[]int", "{{.PSI}}", "[21 22 23]", tVal, true},
   334  	{"*[]int[1]", "{{index .PSI 1}}", "22", tVal, true},
   335  	{"NIL", "{{.NIL}}", "<nil>", tVal, true},
   336  
   337  	// Empty interfaces holding values.
   338  	{"empty nil", "{{.Empty0}}", "<no value>", tVal, true},
   339  	{"empty with int", "{{.Empty1}}", "3", tVal, true},
   340  	{"empty with string", "{{.Empty2}}", "empty2", tVal, true},
   341  	{"empty with slice", "{{.Empty3}}", "[7 8]", tVal, true},
   342  	{"empty with struct", "{{.Empty4}}", "{UinEmpty}", tVal, true},
   343  	{"empty with struct, field", "{{.Empty4.V}}", "UinEmpty", tVal, true},
   344  
   345  	// Edge cases with <no value> with an interface value
   346  	{"field on interface", "{{.foo}}", "<no value>", nil, true},
   347  	{"field on parenthesized interface", "{{(.).foo}}", "<no value>", nil, true},
   348  
   349  	// Method calls.
   350  	{".Method0", "-{{.Method0}}-", "-M0-", tVal, true},
   351  	{".Method1(1234)", "-{{.Method1 1234}}-", "-1234-", tVal, true},
   352  	{".Method1(.I)", "-{{.Method1 .I}}-", "-17-", tVal, true},
   353  	{".Method2(3, .X)", "-{{.Method2 3 .X}}-", "-Method2: 3 x-", tVal, true},
   354  	{".Method2(.U16, `str`)", "-{{.Method2 .U16 `str`}}-", "-Method2: 16 str-", tVal, true},
   355  	{".Method2(.U16, $x)", "{{if $x := .X}}-{{.Method2 .U16 $x}}{{end}}-", "-Method2: 16 x-", tVal, true},
   356  	{".Method3(nil constant)", "-{{.Method3 nil}}-", "-Method3: <nil>-", tVal, true},
   357  	{".Method3(nil value)", "-{{.Method3 .MXI.unset}}-", "-Method3: <nil>-", tVal, true},
   358  	{"method on var", "{{if $x := .}}-{{$x.Method2 .U16 $x.X}}{{end}}-", "-Method2: 16 x-", tVal, true},
   359  	{"method on chained var",
   360  		"{{range .MSIone}}{{if $.U.TrueFalse $.True}}{{$.U.TrueFalse $.True}}{{else}}WRONG{{end}}{{end}}",
   361  		"true", tVal, true},
   362  	{"chained method",
   363  		"{{range .MSIone}}{{if $.GetU.TrueFalse $.True}}{{$.U.TrueFalse $.True}}{{else}}WRONG{{end}}{{end}}",
   364  		"true", tVal, true},
   365  	{"chained method on variable",
   366  		"{{with $x := .}}{{with .SI}}{{$.GetU.TrueFalse $.True}}{{end}}{{end}}",
   367  		"true", tVal, true},
   368  	{".NilOKFunc not nil", "{{call .NilOKFunc .PI}}", "false", tVal, true},
   369  	{".NilOKFunc nil", "{{call .NilOKFunc nil}}", "true", tVal, true},
   370  	{"method on nil value from slice", "-{{range .}}{{.Method1 1234}}{{end}}-", "-1234-", tSliceOfNil, true},
   371  	{"method on typed nil interface value", "{{.NonEmptyInterfaceTypedNil.Method0}}", "M0", tVal, true},
   372  
   373  	// Function call builtin.
   374  	{".BinaryFunc", "{{call .BinaryFunc `1` `2`}}", "[1=2]", tVal, true},
   375  	{".VariadicFunc0", "{{call .VariadicFunc}}", "<>", tVal, true},
   376  	{".VariadicFunc2", "{{call .VariadicFunc `he` `llo`}}", "<he+llo>", tVal, true},
   377  	{".VariadicFuncInt", "{{call .VariadicFuncInt 33 `he` `llo`}}", "33=<he+llo>", tVal, true},
   378  	{"if .BinaryFunc call", "{{ if .BinaryFunc}}{{call .BinaryFunc `1` `2`}}{{end}}", "[1=2]", tVal, true},
   379  	{"if not .BinaryFunc call", "{{ if not .BinaryFunc}}{{call .BinaryFunc `1` `2`}}{{else}}No{{end}}", "No", tVal, true},
   380  	{"Interface Call", `{{stringer .S}}`, "foozle", map[string]interface{}{"S": bytes.NewBufferString("foozle")}, true},
   381  	{".ErrFunc", "{{call .ErrFunc}}", "bla", tVal, true},
   382  	{"call nil", "{{call nil}}", "", tVal, false},
   383  
   384  	// Erroneous function calls (check args).
   385  	{".BinaryFuncTooFew", "{{call .BinaryFunc `1`}}", "", tVal, false},
   386  	{".BinaryFuncTooMany", "{{call .BinaryFunc `1` `2` `3`}}", "", tVal, false},
   387  	{".BinaryFuncBad0", "{{call .BinaryFunc 1 3}}", "", tVal, false},
   388  	{".BinaryFuncBad1", "{{call .BinaryFunc `1` 3}}", "", tVal, false},
   389  	{".VariadicFuncBad0", "{{call .VariadicFunc 3}}", "", tVal, false},
   390  	{".VariadicFuncIntBad0", "{{call .VariadicFuncInt}}", "", tVal, false},
   391  	{".VariadicFuncIntBad`", "{{call .VariadicFuncInt `x`}}", "", tVal, false},
   392  	{".VariadicFuncNilBad", "{{call .VariadicFunc nil}}", "", tVal, false},
   393  
   394  	// Pipelines.
   395  	{"pipeline", "-{{.Method0 | .Method2 .U16}}-", "-Method2: 16 M0-", tVal, true},
   396  	{"pipeline func", "-{{call .VariadicFunc `llo` | call .VariadicFunc `he` }}-", "-<he+<llo>>-", tVal, true},
   397  
   398  	// Nil values aren't missing arguments.
   399  	{"nil pipeline", "{{ .Empty0 | call .NilOKFunc }}", "true", tVal, true},
   400  	{"nil call arg", "{{ call .NilOKFunc .Empty0 }}", "true", tVal, true},
   401  	{"bad nil pipeline", "{{ .Empty0 | .VariadicFunc }}", "", tVal, false},
   402  
   403  	// Parenthesized expressions
   404  	{"parens in pipeline", "{{printf `%d %d %d` (1) (2 | add 3) (add 4 (add 5 6))}}", "1 5 15", tVal, true},
   405  
   406  	// Parenthesized expressions with field accesses
   407  	{"parens: $ in paren", "{{($).X}}", "x", tVal, true},
   408  	{"parens: $.GetU in paren", "{{($.GetU).V}}", "v", tVal, true},
   409  	{"parens: $ in paren in pipe", "{{($ | echo).X}}", "x", tVal, true},
   410  	{"parens: spaces and args", `{{(makemap "up" "down" "left" "right").left}}`, "right", tVal, true},
   411  
   412  	// If.
   413  	{"if true", "{{if true}}TRUE{{end}}", "TRUE", tVal, true},
   414  	{"if false", "{{if false}}TRUE{{else}}FALSE{{end}}", "FALSE", tVal, true},
   415  	{"if nil", "{{if nil}}TRUE{{end}}", "", tVal, false},
   416  	{"if 1", "{{if 1}}NON-ZERO{{else}}ZERO{{end}}", "NON-ZERO", tVal, true},
   417  	{"if 0", "{{if 0}}NON-ZERO{{else}}ZERO{{end}}", "ZERO", tVal, true},
   418  	{"if 1.5", "{{if 1.5}}NON-ZERO{{else}}ZERO{{end}}", "NON-ZERO", tVal, true},
   419  	{"if 0.0", "{{if .FloatZero}}NON-ZERO{{else}}ZERO{{end}}", "ZERO", tVal, true},
   420  	{"if 1.5i", "{{if 1.5i}}NON-ZERO{{else}}ZERO{{end}}", "NON-ZERO", tVal, true},
   421  	{"if 0.0i", "{{if .ComplexZero}}NON-ZERO{{else}}ZERO{{end}}", "ZERO", tVal, true},
   422  	{"if emptystring", "{{if ``}}NON-EMPTY{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
   423  	{"if string", "{{if `notempty`}}NON-EMPTY{{else}}EMPTY{{end}}", "NON-EMPTY", tVal, true},
   424  	{"if emptyslice", "{{if .SIEmpty}}NON-EMPTY{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
   425  	{"if slice", "{{if .SI}}NON-EMPTY{{else}}EMPTY{{end}}", "NON-EMPTY", tVal, true},
   426  	{"if emptymap", "{{if .MSIEmpty}}NON-EMPTY{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
   427  	{"if map", "{{if .MSI}}NON-EMPTY{{else}}EMPTY{{end}}", "NON-EMPTY", tVal, true},
   428  	{"if map unset", "{{if .MXI.none}}NON-ZERO{{else}}ZERO{{end}}", "ZERO", tVal, true},
   429  	{"if map not unset", "{{if not .MXI.none}}ZERO{{else}}NON-ZERO{{end}}", "ZERO", tVal, true},
   430  	{"if $x with $y int", "{{if $x := true}}{{with $y := .I}}{{$x}},{{$y}}{{end}}{{end}}", "true,17", tVal, true},
   431  	{"if $x with $x int", "{{if $x := true}}{{with $x := .I}}{{$x}},{{end}}{{$x}}{{end}}", "17,true", tVal, true},
   432  	{"if else if", "{{if false}}FALSE{{else if true}}TRUE{{end}}", "TRUE", tVal, true},
   433  	{"if else chain", "{{if eq 1 3}}1{{else if eq 2 3}}2{{else if eq 3 3}}3{{end}}", "3", tVal, true},
   434  
   435  	// Print etc.
   436  	{"print", `{{print "hello, print"}}`, "hello, print", tVal, true},
   437  	{"print 123", `{{print 1 2 3}}`, "1 2 3", tVal, true},
   438  	{"print nil", `{{print nil}}`, "<nil>", tVal, true},
   439  	{"println", `{{println 1 2 3}}`, "1 2 3\n", tVal, true},
   440  	{"printf int", `{{printf "%04x" 127}}`, "007f", tVal, true},
   441  	{"printf float", `{{printf "%g" 3.5}}`, "3.5", tVal, true},
   442  	{"printf complex", `{{printf "%g" 1+7i}}`, "(1+7i)", tVal, true},
   443  	{"printf string", `{{printf "%s" "hello"}}`, "hello", tVal, true},
   444  	{"printf function", `{{printf "%#q" zeroArgs}}`, "`zeroArgs`", tVal, true},
   445  	{"printf field", `{{printf "%s" .U.V}}`, "v", tVal, true},
   446  	{"printf method", `{{printf "%s" .Method0}}`, "M0", tVal, true},
   447  	{"printf dot", `{{with .I}}{{printf "%d" .}}{{end}}`, "17", tVal, true},
   448  	{"printf var", `{{with $x := .I}}{{printf "%d" $x}}{{end}}`, "17", tVal, true},
   449  	{"printf lots", `{{printf "%d %s %g %s" 127 "hello" 7-3i .Method0}}`, "127 hello (7-3i) M0", tVal, true},
   450  
   451  	// HTML.
   452  	{"html", `{{html "<script>alert(\"XSS\");</script>"}}`,
   453  		"&lt;script&gt;alert(&#34;XSS&#34;);&lt;/script&gt;", nil, true},
   454  	{"html pipeline", `{{printf "<script>alert(\"XSS\");</script>" | html}}`,
   455  		"&lt;script&gt;alert(&#34;XSS&#34;);&lt;/script&gt;", nil, true},
   456  	{"html", `{{html .PS}}`, "a string", tVal, true},
   457  	{"html typed nil", `{{html .NIL}}`, "&lt;nil&gt;", tVal, true},
   458  	{"html untyped nil", `{{html .Empty0}}`, "&lt;no value&gt;", tVal, true},
   459  
   460  	// JavaScript.
   461  	{"js", `{{js .}}`, `It\'d be nice.`, `It'd be nice.`, true},
   462  
   463  	// URL query.
   464  	{"urlquery", `{{"http://www.example.org/"|urlquery}}`, "http%3A%2F%2Fwww.example.org%2F", nil, true},
   465  
   466  	// Booleans
   467  	{"not", "{{not true}} {{not false}}", "false true", nil, true},
   468  	{"and", "{{and false 0}} {{and 1 0}} {{and 0 true}} {{and 1 1}}", "false 0 0 1", nil, true},
   469  	{"or", "{{or 0 0}} {{or 1 0}} {{or 0 true}} {{or 1 1}}", "0 1 true 1", nil, true},
   470  	{"boolean if", "{{if and true 1 `hi`}}TRUE{{else}}FALSE{{end}}", "TRUE", tVal, true},
   471  	{"boolean if not", "{{if and true 1 `hi` | not}}TRUE{{else}}FALSE{{end}}", "FALSE", nil, true},
   472  
   473  	// Indexing.
   474  	{"slice[0]", "{{index .SI 0}}", "3", tVal, true},
   475  	{"slice[1]", "{{index .SI 1}}", "4", tVal, true},
   476  	{"slice[HUGE]", "{{index .SI 10}}", "", tVal, false},
   477  	{"slice[WRONG]", "{{index .SI `hello`}}", "", tVal, false},
   478  	{"slice[nil]", "{{index .SI nil}}", "", tVal, false},
   479  	{"map[one]", "{{index .MSI `one`}}", "1", tVal, true},
   480  	{"map[two]", "{{index .MSI `two`}}", "2", tVal, true},
   481  	{"map[NO]", "{{index .MSI `XXX`}}", "0", tVal, true},
   482  	{"map[nil]", "{{index .MSI nil}}", "", tVal, false},
   483  	{"map[``]", "{{index .MSI ``}}", "0", tVal, true},
   484  	{"map[WRONG]", "{{index .MSI 10}}", "", tVal, false},
   485  	{"double index", "{{index .SMSI 1 `eleven`}}", "11", tVal, true},
   486  	{"nil[1]", "{{index nil 1}}", "", tVal, false},
   487  	{"map MI64S", "{{index .MI64S 2}}", "i642", tVal, true},
   488  	{"map MI32S", "{{index .MI32S 2}}", "two", tVal, true},
   489  	{"map MUI64S", "{{index .MUI64S 3}}", "ui643", tVal, true},
   490  	{"map MI8S", "{{index .MI8S 3}}", "i83", tVal, true},
   491  	{"map MUI8S", "{{index .MUI8S 2}}", "u82", tVal, true},
   492  
   493  	// Len.
   494  	{"slice", "{{len .SI}}", "3", tVal, true},
   495  	{"map", "{{len .MSI }}", "3", tVal, true},
   496  	{"len of int", "{{len 3}}", "", tVal, false},
   497  	{"len of nothing", "{{len .Empty0}}", "", tVal, false},
   498  
   499  	// With.
   500  	{"with true", "{{with true}}{{.}}{{end}}", "true", tVal, true},
   501  	{"with false", "{{with false}}{{.}}{{else}}FALSE{{end}}", "FALSE", tVal, true},
   502  	{"with 1", "{{with 1}}{{.}}{{else}}ZERO{{end}}", "1", tVal, true},
   503  	{"with 0", "{{with 0}}{{.}}{{else}}ZERO{{end}}", "ZERO", tVal, true},
   504  	{"with 1.5", "{{with 1.5}}{{.}}{{else}}ZERO{{end}}", "1.5", tVal, true},
   505  	{"with 0.0", "{{with .FloatZero}}{{.}}{{else}}ZERO{{end}}", "ZERO", tVal, true},
   506  	{"with 1.5i", "{{with 1.5i}}{{.}}{{else}}ZERO{{end}}", "(0+1.5i)", tVal, true},
   507  	{"with 0.0i", "{{with .ComplexZero}}{{.}}{{else}}ZERO{{end}}", "ZERO", tVal, true},
   508  	{"with emptystring", "{{with ``}}{{.}}{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
   509  	{"with string", "{{with `notempty`}}{{.}}{{else}}EMPTY{{end}}", "notempty", tVal, true},
   510  	{"with emptyslice", "{{with .SIEmpty}}{{.}}{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
   511  	{"with slice", "{{with .SI}}{{.}}{{else}}EMPTY{{end}}", "[3 4 5]", tVal, true},
   512  	{"with emptymap", "{{with .MSIEmpty}}{{.}}{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
   513  	{"with map", "{{with .MSIone}}{{.}}{{else}}EMPTY{{end}}", "map[one:1]", tVal, true},
   514  	{"with empty interface, struct field", "{{with .Empty4}}{{.V}}{{end}}", "UinEmpty", tVal, true},
   515  	{"with $x int", "{{with $x := .I}}{{$x}}{{end}}", "17", tVal, true},
   516  	{"with $x struct.U.V", "{{with $x := $}}{{$x.U.V}}{{end}}", "v", tVal, true},
   517  	{"with variable and action", "{{with $x := $}}{{$y := $.U.V}}{{$y}}{{end}}", "v", tVal, true},
   518  
   519  	// Range.
   520  	{"range []int", "{{range .SI}}-{{.}}-{{end}}", "-3--4--5-", tVal, true},
   521  	{"range empty no else", "{{range .SIEmpty}}-{{.}}-{{end}}", "", tVal, true},
   522  	{"range []int else", "{{range .SI}}-{{.}}-{{else}}EMPTY{{end}}", "-3--4--5-", tVal, true},
   523  	{"range empty else", "{{range .SIEmpty}}-{{.}}-{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
   524  	{"range []bool", "{{range .SB}}-{{.}}-{{end}}", "-true--false-", tVal, true},
   525  	{"range []int method", "{{range .SI | .MAdd .I}}-{{.}}-{{end}}", "-20--21--22-", tVal, true},
   526  	{"range map", "{{range .MSI}}-{{.}}-{{end}}", "-1--3--2-", tVal, true},
   527  	{"range empty map no else", "{{range .MSIEmpty}}-{{.}}-{{end}}", "", tVal, true},
   528  	{"range map else", "{{range .MSI}}-{{.}}-{{else}}EMPTY{{end}}", "-1--3--2-", tVal, true},
   529  	{"range empty map else", "{{range .MSIEmpty}}-{{.}}-{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
   530  	{"range empty interface", "{{range .Empty3}}-{{.}}-{{else}}EMPTY{{end}}", "-7--8-", tVal, true},
   531  	{"range empty nil", "{{range .Empty0}}-{{.}}-{{end}}", "", tVal, true},
   532  	{"range $x SI", "{{range $x := .SI}}<{{$x}}>{{end}}", "<3><4><5>", tVal, true},
   533  	{"range $x $y SI", "{{range $x, $y := .SI}}<{{$x}}={{$y}}>{{end}}", "<0=3><1=4><2=5>", tVal, true},
   534  	{"range $x MSIone", "{{range $x := .MSIone}}<{{$x}}>{{end}}", "<1>", tVal, true},
   535  	{"range $x $y MSIone", "{{range $x, $y := .MSIone}}<{{$x}}={{$y}}>{{end}}", "<one=1>", tVal, true},
   536  	{"range $x PSI", "{{range $x := .PSI}}<{{$x}}>{{end}}", "<21><22><23>", tVal, true},
   537  	{"declare in range", "{{range $x := .PSI}}<{{$foo:=$x}}{{$x}}>{{end}}", "<21><22><23>", tVal, true},
   538  	{"range count", `{{range $i, $x := count 5}}[{{$i}}]{{$x}}{{end}}`, "[0]a[1]b[2]c[3]d[4]e", tVal, true},
   539  	{"range nil count", `{{range $i, $x := count 0}}{{else}}empty{{end}}`, "empty", tVal, true},
   540  
   541  	// Cute examples.
   542  	{"or as if true", `{{or .SI "slice is empty"}}`, "[3 4 5]", tVal, true},
   543  	{"or as if false", `{{or .SIEmpty "slice is empty"}}`, "slice is empty", tVal, true},
   544  
   545  	// Error handling.
   546  	{"error method, error", "{{.MyError true}}", "", tVal, false},
   547  	{"error method, no error", "{{.MyError false}}", "false", tVal, true},
   548  
   549  	// Fixed bugs.
   550  	// Must separate dot and receiver; otherwise args are evaluated with dot set to variable.
   551  	{"bug0", "{{range .MSIone}}{{if $.Method1 .}}X{{end}}{{end}}", "X", tVal, true},
   552  	// Do not loop endlessly in indirect for non-empty interfaces.
   553  	// The bug appears with *interface only; looped forever.
   554  	{"bug1", "{{.Method0}}", "M0", &iVal, true},
   555  	// Was taking address of interface field, so method set was empty.
   556  	{"bug2", "{{$.NonEmptyInterface.Method0}}", "M0", tVal, true},
   557  	// Struct values were not legal in with - mere oversight.
   558  	{"bug3", "{{with $}}{{.Method0}}{{end}}", "M0", tVal, true},
   559  	// Nil interface values in if.
   560  	{"bug4", "{{if .Empty0}}non-nil{{else}}nil{{end}}", "nil", tVal, true},
   561  	// Stringer.
   562  	{"bug5", "{{.Str}}", "foozle", tVal, true},
   563  	{"bug5a", "{{.Err}}", "erroozle", tVal, true},
   564  	// Args need to be indirected and dereferenced sometimes.
   565  	{"bug6a", "{{vfunc .V0 .V1}}", "vfunc", tVal, true},
   566  	{"bug6b", "{{vfunc .V0 .V0}}", "vfunc", tVal, true},
   567  	{"bug6c", "{{vfunc .V1 .V0}}", "vfunc", tVal, true},
   568  	{"bug6d", "{{vfunc .V1 .V1}}", "vfunc", tVal, true},
   569  	// Legal parse but illegal execution: non-function should have no arguments.
   570  	{"bug7a", "{{3 2}}", "", tVal, false},
   571  	{"bug7b", "{{$x := 1}}{{$x 2}}", "", tVal, false},
   572  	{"bug7c", "{{$x := 1}}{{3 | $x}}", "", tVal, false},
   573  	// Pipelined arg was not being type-checked.
   574  	{"bug8a", "{{3|oneArg}}", "", tVal, false},
   575  	{"bug8b", "{{4|dddArg 3}}", "", tVal, false},
   576  	// A bug was introduced that broke map lookups for lower-case names.
   577  	{"bug9", "{{.cause}}", "neglect", map[string]string{"cause": "neglect"}, true},
   578  	// Field chain starting with function did not work.
   579  	{"bug10", "{{mapOfThree.three}}-{{(mapOfThree).three}}", "3-3", 0, true},
   580  	// Dereferencing nil pointer while evaluating function arguments should not panic. Issue 7333.
   581  	{"bug11", "{{valueString .PS}}", "", T{}, false},
   582  	// 0xef gave constant type float64. Issue 8622.
   583  	{"bug12xe", "{{printf `%T` 0xef}}", "int", T{}, true},
   584  	{"bug12xE", "{{printf `%T` 0xEE}}", "int", T{}, true},
   585  	{"bug12Xe", "{{printf `%T` 0Xef}}", "int", T{}, true},
   586  	{"bug12XE", "{{printf `%T` 0XEE}}", "int", T{}, true},
   587  	// Chained nodes did not work as arguments. Issue 8473.
   588  	{"bug13", "{{print (.Copy).I}}", "17", tVal, true},
   589  	// Didn't protect against nil or literal values in field chains.
   590  	{"bug14a", "{{(nil).True}}", "", tVal, false},
   591  	{"bug14b", "{{$x := nil}}{{$x.anything}}", "", tVal, false},
   592  	{"bug14c", `{{$x := (1.0)}}{{$y := ("hello")}}{{$x.anything}}{{$y.true}}`, "", tVal, false},
   593  	// Didn't call validateType on function results. Issue 10800.
   594  	{"bug15", "{{valueString returnInt}}", "", tVal, false},
   595  	// Variadic function corner cases. Issue 10946.
   596  	{"bug16a", "{{true|printf}}", "", tVal, false},
   597  	{"bug16b", "{{1|printf}}", "", tVal, false},
   598  	{"bug16c", "{{1.1|printf}}", "", tVal, false},
   599  	{"bug16d", "{{'x'|printf}}", "", tVal, false},
   600  	{"bug16e", "{{0i|printf}}", "", tVal, false},
   601  	{"bug16f", "{{true|twoArgs \"xxx\"}}", "", tVal, false},
   602  	{"bug16g", "{{\"aaa\" |twoArgs \"bbb\"}}", "twoArgs=bbbaaa", tVal, true},
   603  	{"bug16h", "{{1|oneArg}}", "", tVal, false},
   604  	{"bug16i", "{{\"aaa\"|oneArg}}", "oneArg=aaa", tVal, true},
   605  	{"bug16j", "{{1+2i|printf \"%v\"}}", "(1+2i)", tVal, true},
   606  	{"bug16k", "{{\"aaa\"|printf }}", "aaa", tVal, true},
   607  	{"bug17a", "{{.NonEmptyInterface.X}}", "x", tVal, true},
   608  	{"bug17b", "-{{.NonEmptyInterface.Method1 1234}}-", "-1234-", tVal, true},
   609  	{"bug17c", "{{len .NonEmptyInterfacePtS}}", "2", tVal, true},
   610  	{"bug17d", "{{index .NonEmptyInterfacePtS 0}}", "a", tVal, true},
   611  	{"bug17e", "{{range .NonEmptyInterfacePtS}}-{{.}}-{{end}}", "-a--b-", tVal, true},
   612  }
   613  
   614  func zeroArgs() string {
   615  	return "zeroArgs"
   616  }
   617  
   618  func oneArg(a string) string {
   619  	return "oneArg=" + a
   620  }
   621  
   622  func twoArgs(a, b string) string {
   623  	return "twoArgs=" + a + b
   624  }
   625  
   626  func dddArg(a int, b ...string) string {
   627  	return fmt.Sprintln(a, b)
   628  }
   629  
   630  // count returns a channel that will deliver n sequential 1-letter strings starting at "a"
   631  func count(n int) chan string {
   632  	if n == 0 {
   633  		return nil
   634  	}
   635  	c := make(chan string)
   636  	go func() {
   637  		for i := 0; i < n; i++ {
   638  			c <- "abcdefghijklmnop"[i : i+1]
   639  		}
   640  		close(c)
   641  	}()
   642  	return c
   643  }
   644  
   645  // vfunc takes a *V and a V
   646  func vfunc(V, *V) string {
   647  	return "vfunc"
   648  }
   649  
   650  // valueString takes a string, not a pointer.
   651  func valueString(v string) string {
   652  	return "value is ignored"
   653  }
   654  
   655  // returnInt returns an int
   656  func returnInt() int {
   657  	return 7
   658  }
   659  
   660  func add(args ...int) int {
   661  	sum := 0
   662  	for _, x := range args {
   663  		sum += x
   664  	}
   665  	return sum
   666  }
   667  
   668  func echo(arg interface{}) interface{} {
   669  	return arg
   670  }
   671  
   672  func makemap(arg ...string) map[string]string {
   673  	if len(arg)%2 != 0 {
   674  		panic("bad makemap")
   675  	}
   676  	m := make(map[string]string)
   677  	for i := 0; i < len(arg); i += 2 {
   678  		m[arg[i]] = arg[i+1]
   679  	}
   680  	return m
   681  }
   682  
   683  func stringer(s fmt.Stringer) string {
   684  	return s.String()
   685  }
   686  
   687  func mapOfThree() interface{} {
   688  	return map[string]int{"three": 3}
   689  }
   690  
   691  func testExecute(execTests []execTest, template *Template, t *testing.T) {
   692  	b := new(bytes.Buffer)
   693  	funcs := FuncMap{
   694  		"add":         add,
   695  		"count":       count,
   696  		"dddArg":      dddArg,
   697  		"echo":        echo,
   698  		"makemap":     makemap,
   699  		"mapOfThree":  mapOfThree,
   700  		"oneArg":      oneArg,
   701  		"returnInt":   returnInt,
   702  		"stringer":    stringer,
   703  		"twoArgs":     twoArgs,
   704  		"typeOf":      typeOf,
   705  		"valueString": valueString,
   706  		"vfunc":       vfunc,
   707  		"zeroArgs":    zeroArgs,
   708  	}
   709  	for _, test := range execTests {
   710  		var tmpl *Template
   711  		var err error
   712  		if template == nil {
   713  			tmpl, err = New(test.name).Funcs(funcs).Parse(test.input)
   714  		} else {
   715  			tmpl, err = template.New(test.name).Funcs(funcs).Parse(test.input)
   716  		}
   717  		if err != nil {
   718  			t.Errorf("%s: parse error: %s", test.name, err)
   719  			continue
   720  		}
   721  		b.Reset()
   722  		err = tmpl.Execute(b, test.data)
   723  		switch {
   724  		case !test.ok && err == nil:
   725  			t.Errorf("%s: expected error; got none", test.name)
   726  			continue
   727  		case test.ok && err != nil:
   728  			t.Errorf("%s: unexpected execute error: %s", test.name, err)
   729  			continue
   730  		case !test.ok && err != nil:
   731  			// expected error, got one
   732  			if *debug {
   733  				fmt.Printf("%s: %s\n\t%s\n", test.name, test.input, err)
   734  			}
   735  		}
   736  		result := b.String()
   737  		if result != test.output {
   738  			t.Errorf("%s: expected\n\t%q\ngot\n\t%q", test.name, test.output, result)
   739  		}
   740  	}
   741  }
   742  
   743  func TestExecute(t *testing.T) {
   744  	testExecute(execTests, nil, t)
   745  }
   746  
   747  var delimPairs = []string{
   748  	"", "", // default
   749  	"{{", "}}", // same as default
   750  	"<<", ">>", // distinct
   751  	"|", "|", // same
   752  	"(日)", "(本)", // peculiar
   753  }
   754  
   755  func TestDelims(t *testing.T) {
   756  	const hello = "Hello, world"
   757  	var value = struct{ Str string }{hello}
   758  	for i := 0; i < len(delimPairs); i += 2 {
   759  		text := ".Str"
   760  		left := delimPairs[i+0]
   761  		trueLeft := left
   762  		right := delimPairs[i+1]
   763  		trueRight := right
   764  		if left == "" { // default case
   765  			trueLeft = "{{"
   766  		}
   767  		if right == "" { // default case
   768  			trueRight = "}}"
   769  		}
   770  		text = trueLeft + text + trueRight
   771  		// Now add a comment
   772  		text += trueLeft + "/*comment*/" + trueRight
   773  		// Now add  an action containing a string.
   774  		text += trueLeft + `"` + trueLeft + `"` + trueRight
   775  		// At this point text looks like `{{.Str}}{{/*comment*/}}{{"{{"}}`.
   776  		tmpl, err := New("delims").Delims(left, right).Parse(text)
   777  		if err != nil {
   778  			t.Fatalf("delim %q text %q parse err %s", left, text, err)
   779  		}
   780  		var b = new(bytes.Buffer)
   781  		err = tmpl.Execute(b, value)
   782  		if err != nil {
   783  			t.Fatalf("delim %q exec err %s", left, err)
   784  		}
   785  		if b.String() != hello+trueLeft {
   786  			t.Errorf("expected %q got %q", hello+trueLeft, b.String())
   787  		}
   788  	}
   789  }
   790  
   791  // Check that an error from a method flows back to the top.
   792  func TestExecuteError(t *testing.T) {
   793  	b := new(bytes.Buffer)
   794  	tmpl := New("error")
   795  	_, err := tmpl.Parse("{{.MyError true}}")
   796  	if err != nil {
   797  		t.Fatalf("parse error: %s", err)
   798  	}
   799  	err = tmpl.Execute(b, tVal)
   800  	if err == nil {
   801  		t.Errorf("expected error; got none")
   802  	} else if !strings.Contains(err.Error(), myError.Error()) {
   803  		if *debug {
   804  			fmt.Printf("test execute error: %s\n", err)
   805  		}
   806  		t.Errorf("expected myError; got %s", err)
   807  	}
   808  }
   809  
   810  const execErrorText = `line 1
   811  line 2
   812  line 3
   813  {{template "one" .}}
   814  {{define "one"}}{{template "two" .}}{{end}}
   815  {{define "two"}}{{template "three" .}}{{end}}
   816  {{define "three"}}{{index "hi" $}}{{end}}`
   817  
   818  // Check that an error from a nested template contains all the relevant information.
   819  func TestExecError(t *testing.T) {
   820  	tmpl, err := New("top").Parse(execErrorText)
   821  	if err != nil {
   822  		t.Fatal("parse error:", err)
   823  	}
   824  	var b bytes.Buffer
   825  	err = tmpl.Execute(&b, 5) // 5 is out of range indexing "hi"
   826  	if err == nil {
   827  		t.Fatal("expected error")
   828  	}
   829  	const want = `template: top:7:20: executing "three" at <index "hi" $>: error calling index: index out of range: 5`
   830  	got := err.Error()
   831  	if got != want {
   832  		t.Errorf("expected\n%q\ngot\n%q", want, got)
   833  	}
   834  }
   835  
   836  func TestJSEscaping(t *testing.T) {
   837  	testCases := []struct {
   838  		in, exp string
   839  	}{
   840  		{`a`, `a`},
   841  		{`'foo`, `\'foo`},
   842  		{`Go "jump" \`, `Go \"jump\" \\`},
   843  		{`Yukihiro says "今日は世界"`, `Yukihiro says \"今日は世界\"`},
   844  		{"unprintable \uFDFF", `unprintable \uFDFF`},
   845  		{`<html>`, `\x3Chtml\x3E`},
   846  	}
   847  	for _, tc := range testCases {
   848  		s := JSEscapeString(tc.in)
   849  		if s != tc.exp {
   850  			t.Errorf("JS escaping [%s] got [%s] want [%s]", tc.in, s, tc.exp)
   851  		}
   852  	}
   853  }
   854  
   855  // A nice example: walk a binary tree.
   856  
   857  type Tree struct {
   858  	Val         int
   859  	Left, Right *Tree
   860  }
   861  
   862  // Use different delimiters to test Set.Delims.
   863  // Also test the trimming of leading and trailing spaces.
   864  const treeTemplate = `
   865  	(- define "tree" -)
   866  	[
   867  		(- .Val -)
   868  		(- with .Left -)
   869  			(template "tree" . -)
   870  		(- end -)
   871  		(- with .Right -)
   872  			(- template "tree" . -)
   873  		(- end -)
   874  	]
   875  	(- end -)
   876  `
   877  
   878  func TestTree(t *testing.T) {
   879  	var tree = &Tree{
   880  		1,
   881  		&Tree{
   882  			2, &Tree{
   883  				3,
   884  				&Tree{
   885  					4, nil, nil,
   886  				},
   887  				nil,
   888  			},
   889  			&Tree{
   890  				5,
   891  				&Tree{
   892  					6, nil, nil,
   893  				},
   894  				nil,
   895  			},
   896  		},
   897  		&Tree{
   898  			7,
   899  			&Tree{
   900  				8,
   901  				&Tree{
   902  					9, nil, nil,
   903  				},
   904  				nil,
   905  			},
   906  			&Tree{
   907  				10,
   908  				&Tree{
   909  					11, nil, nil,
   910  				},
   911  				nil,
   912  			},
   913  		},
   914  	}
   915  	tmpl, err := New("root").Delims("(", ")").Parse(treeTemplate)
   916  	if err != nil {
   917  		t.Fatal("parse error:", err)
   918  	}
   919  	var b bytes.Buffer
   920  	const expect = "[1[2[3[4]][5[6]]][7[8[9]][10[11]]]]"
   921  	// First by looking up the template.
   922  	err = tmpl.Lookup("tree").Execute(&b, tree)
   923  	if err != nil {
   924  		t.Fatal("exec error:", err)
   925  	}
   926  	result := b.String()
   927  	if result != expect {
   928  		t.Errorf("expected %q got %q", expect, result)
   929  	}
   930  	// Then direct to execution.
   931  	b.Reset()
   932  	err = tmpl.ExecuteTemplate(&b, "tree", tree)
   933  	if err != nil {
   934  		t.Fatal("exec error:", err)
   935  	}
   936  	result = b.String()
   937  	if result != expect {
   938  		t.Errorf("expected %q got %q", expect, result)
   939  	}
   940  }
   941  
   942  func TestExecuteOnNewTemplate(t *testing.T) {
   943  	// This is issue 3872.
   944  	New("Name").Templates()
   945  	// This is issue 11379.
   946  	new(Template).Templates()
   947  	new(Template).Parse("")
   948  	new(Template).New("abc").Parse("")
   949  	new(Template).Execute(nil, nil)                // returns an error (but does not crash)
   950  	new(Template).ExecuteTemplate(nil, "XXX", nil) // returns an error (but does not crash)
   951  }
   952  
   953  const testTemplates = `{{define "one"}}one{{end}}{{define "two"}}two{{end}}`
   954  
   955  func TestMessageForExecuteEmpty(t *testing.T) {
   956  	// Test a truly empty template.
   957  	tmpl := New("empty")
   958  	var b bytes.Buffer
   959  	err := tmpl.Execute(&b, 0)
   960  	if err == nil {
   961  		t.Fatal("expected initial error")
   962  	}
   963  	got := err.Error()
   964  	want := `template: empty: "empty" is an incomplete or empty template`
   965  	if got != want {
   966  		t.Errorf("expected error %s got %s", want, got)
   967  	}
   968  	// Add a non-empty template to check that the error is helpful.
   969  	tests, err := New("").Parse(testTemplates)
   970  	if err != nil {
   971  		t.Fatal(err)
   972  	}
   973  	tmpl.AddParseTree("secondary", tests.Tree)
   974  	err = tmpl.Execute(&b, 0)
   975  	if err == nil {
   976  		t.Fatal("expected second error")
   977  	}
   978  	got = err.Error()
   979  	want = `template: empty: "empty" is an incomplete or empty template`
   980  	if got != want {
   981  		t.Errorf("expected error %s got %s", want, got)
   982  	}
   983  	// Make sure we can execute the secondary.
   984  	err = tmpl.ExecuteTemplate(&b, "secondary", 0)
   985  	if err != nil {
   986  		t.Fatal(err)
   987  	}
   988  }
   989  
   990  func TestFinalForPrintf(t *testing.T) {
   991  	tmpl, err := New("").Parse(`{{"x" | printf}}`)
   992  	if err != nil {
   993  		t.Fatal(err)
   994  	}
   995  	var b bytes.Buffer
   996  	err = tmpl.Execute(&b, 0)
   997  	if err != nil {
   998  		t.Fatal(err)
   999  	}
  1000  }
  1001  
  1002  type cmpTest struct {
  1003  	expr  string
  1004  	truth string
  1005  	ok    bool
  1006  }
  1007  
  1008  var cmpTests = []cmpTest{
  1009  	{"eq true true", "true", true},
  1010  	{"eq true false", "false", true},
  1011  	{"eq 1+2i 1+2i", "true", true},
  1012  	{"eq 1+2i 1+3i", "false", true},
  1013  	{"eq 1.5 1.5", "true", true},
  1014  	{"eq 1.5 2.5", "false", true},
  1015  	{"eq 1 1", "true", true},
  1016  	{"eq 1 2", "false", true},
  1017  	{"eq `xy` `xy`", "true", true},
  1018  	{"eq `xy` `xyz`", "false", true},
  1019  	{"eq .Uthree .Uthree", "true", true},
  1020  	{"eq .Uthree .Ufour", "false", true},
  1021  	{"eq 3 4 5 6 3", "true", true},
  1022  	{"eq 3 4 5 6 7", "false", true},
  1023  	{"ne true true", "false", true},
  1024  	{"ne true false", "true", true},
  1025  	{"ne 1+2i 1+2i", "false", true},
  1026  	{"ne 1+2i 1+3i", "true", true},
  1027  	{"ne 1.5 1.5", "false", true},
  1028  	{"ne 1.5 2.5", "true", true},
  1029  	{"ne 1 1", "false", true},
  1030  	{"ne 1 2", "true", true},
  1031  	{"ne `xy` `xy`", "false", true},
  1032  	{"ne `xy` `xyz`", "true", true},
  1033  	{"ne .Uthree .Uthree", "false", true},
  1034  	{"ne .Uthree .Ufour", "true", true},
  1035  	{"lt 1.5 1.5", "false", true},
  1036  	{"lt 1.5 2.5", "true", true},
  1037  	{"lt 1 1", "false", true},
  1038  	{"lt 1 2", "true", true},
  1039  	{"lt `xy` `xy`", "false", true},
  1040  	{"lt `xy` `xyz`", "true", true},
  1041  	{"lt .Uthree .Uthree", "false", true},
  1042  	{"lt .Uthree .Ufour", "true", true},
  1043  	{"le 1.5 1.5", "true", true},
  1044  	{"le 1.5 2.5", "true", true},
  1045  	{"le 2.5 1.5", "false", true},
  1046  	{"le 1 1", "true", true},
  1047  	{"le 1 2", "true", true},
  1048  	{"le 2 1", "false", true},
  1049  	{"le `xy` `xy`", "true", true},
  1050  	{"le `xy` `xyz`", "true", true},
  1051  	{"le `xyz` `xy`", "false", true},
  1052  	{"le .Uthree .Uthree", "true", true},
  1053  	{"le .Uthree .Ufour", "true", true},
  1054  	{"le .Ufour .Uthree", "false", true},
  1055  	{"gt 1.5 1.5", "false", true},
  1056  	{"gt 1.5 2.5", "false", true},
  1057  	{"gt 1 1", "false", true},
  1058  	{"gt 2 1", "true", true},
  1059  	{"gt 1 2", "false", true},
  1060  	{"gt `xy` `xy`", "false", true},
  1061  	{"gt `xy` `xyz`", "false", true},
  1062  	{"gt .Uthree .Uthree", "false", true},
  1063  	{"gt .Uthree .Ufour", "false", true},
  1064  	{"gt .Ufour .Uthree", "true", true},
  1065  	{"ge 1.5 1.5", "true", true},
  1066  	{"ge 1.5 2.5", "false", true},
  1067  	{"ge 2.5 1.5", "true", true},
  1068  	{"ge 1 1", "true", true},
  1069  	{"ge 1 2", "false", true},
  1070  	{"ge 2 1", "true", true},
  1071  	{"ge `xy` `xy`", "true", true},
  1072  	{"ge `xy` `xyz`", "false", true},
  1073  	{"ge `xyz` `xy`", "true", true},
  1074  	{"ge .Uthree .Uthree", "true", true},
  1075  	{"ge .Uthree .Ufour", "false", true},
  1076  	{"ge .Ufour .Uthree", "true", true},
  1077  	// Mixing signed and unsigned integers.
  1078  	{"eq .Uthree .Three", "true", true},
  1079  	{"eq .Three .Uthree", "true", true},
  1080  	{"le .Uthree .Three", "true", true},
  1081  	{"le .Three .Uthree", "true", true},
  1082  	{"ge .Uthree .Three", "true", true},
  1083  	{"ge .Three .Uthree", "true", true},
  1084  	{"lt .Uthree .Three", "false", true},
  1085  	{"lt .Three .Uthree", "false", true},
  1086  	{"gt .Uthree .Three", "false", true},
  1087  	{"gt .Three .Uthree", "false", true},
  1088  	{"eq .Ufour .Three", "false", true},
  1089  	{"lt .Ufour .Three", "false", true},
  1090  	{"gt .Ufour .Three", "true", true},
  1091  	{"eq .NegOne .Uthree", "false", true},
  1092  	{"eq .Uthree .NegOne", "false", true},
  1093  	{"ne .NegOne .Uthree", "true", true},
  1094  	{"ne .Uthree .NegOne", "true", true},
  1095  	{"lt .NegOne .Uthree", "true", true},
  1096  	{"lt .Uthree .NegOne", "false", true},
  1097  	{"le .NegOne .Uthree", "true", true},
  1098  	{"le .Uthree .NegOne", "false", true},
  1099  	{"gt .NegOne .Uthree", "false", true},
  1100  	{"gt .Uthree .NegOne", "true", true},
  1101  	{"ge .NegOne .Uthree", "false", true},
  1102  	{"ge .Uthree .NegOne", "true", true},
  1103  	{"eq (index `x` 0) 'x'", "true", true}, // The example that triggered this rule.
  1104  	{"eq (index `x` 0) 'y'", "false", true},
  1105  	// Errors
  1106  	{"eq `xy` 1", "", false},    // Different types.
  1107  	{"eq 2 2.0", "", false},     // Different types.
  1108  	{"lt true true", "", false}, // Unordered types.
  1109  	{"lt 1+0i 1+0i", "", false}, // Unordered types.
  1110  }
  1111  
  1112  func TestComparison(t *testing.T) {
  1113  	b := new(bytes.Buffer)
  1114  	var cmpStruct = struct {
  1115  		Uthree, Ufour uint
  1116  		NegOne, Three int
  1117  	}{3, 4, -1, 3}
  1118  	for _, test := range cmpTests {
  1119  		text := fmt.Sprintf("{{if %s}}true{{else}}false{{end}}", test.expr)
  1120  		tmpl, err := New("empty").Parse(text)
  1121  		if err != nil {
  1122  			t.Fatalf("%q: %s", test.expr, err)
  1123  		}
  1124  		b.Reset()
  1125  		err = tmpl.Execute(b, &cmpStruct)
  1126  		if test.ok && err != nil {
  1127  			t.Errorf("%s errored incorrectly: %s", test.expr, err)
  1128  			continue
  1129  		}
  1130  		if !test.ok && err == nil {
  1131  			t.Errorf("%s did not error", test.expr)
  1132  			continue
  1133  		}
  1134  		if b.String() != test.truth {
  1135  			t.Errorf("%s: want %s; got %s", test.expr, test.truth, b.String())
  1136  		}
  1137  	}
  1138  }
  1139  
  1140  func TestMissingMapKey(t *testing.T) {
  1141  	data := map[string]int{
  1142  		"x": 99,
  1143  	}
  1144  	tmpl, err := New("t1").Parse("{{.x}} {{.y}}")
  1145  	if err != nil {
  1146  		t.Fatal(err)
  1147  	}
  1148  	var b bytes.Buffer
  1149  	// By default, just get "<no value>"
  1150  	err = tmpl.Execute(&b, data)
  1151  	if err != nil {
  1152  		t.Fatal(err)
  1153  	}
  1154  	want := "99 <no value>"
  1155  	got := b.String()
  1156  	if got != want {
  1157  		t.Errorf("got %q; expected %q", got, want)
  1158  	}
  1159  	// Same if we set the option explicitly to the default.
  1160  	tmpl.Option("missingkey=default")
  1161  	b.Reset()
  1162  	err = tmpl.Execute(&b, data)
  1163  	if err != nil {
  1164  		t.Fatal("default:", err)
  1165  	}
  1166  	want = "99 <no value>"
  1167  	got = b.String()
  1168  	if got != want {
  1169  		t.Errorf("got %q; expected %q", got, want)
  1170  	}
  1171  	// Next we ask for a zero value
  1172  	tmpl.Option("missingkey=zero")
  1173  	b.Reset()
  1174  	err = tmpl.Execute(&b, data)
  1175  	if err != nil {
  1176  		t.Fatal("zero:", err)
  1177  	}
  1178  	want = "99 0"
  1179  	got = b.String()
  1180  	if got != want {
  1181  		t.Errorf("got %q; expected %q", got, want)
  1182  	}
  1183  	// Now we ask for an error.
  1184  	tmpl.Option("missingkey=error")
  1185  	err = tmpl.Execute(&b, data)
  1186  	if err == nil {
  1187  		t.Errorf("expected error; got none")
  1188  	}
  1189  	// same Option, but now a nil interface: ask for an error
  1190  	err = tmpl.Execute(&b, nil)
  1191  	t.Log(err)
  1192  	if err == nil {
  1193  		t.Errorf("expected error for nil-interface; got none")
  1194  	}
  1195  }
  1196  
  1197  // Test that the error message for multiline unterminated string
  1198  // refers to the line number of the opening quote.
  1199  func TestUnterminatedStringError(t *testing.T) {
  1200  	_, err := New("X").Parse("hello\n\n{{`unterminated\n\n\n\n}}\n some more\n\n")
  1201  	if err == nil {
  1202  		t.Fatal("expected error")
  1203  	}
  1204  	str := err.Error()
  1205  	if !strings.Contains(str, "X:3: unexpected unterminated raw quoted string") {
  1206  		t.Fatalf("unexpected error: %s", str)
  1207  	}
  1208  }
  1209  
  1210  const alwaysErrorText = "always be failing"
  1211  
  1212  var alwaysError = errors.New(alwaysErrorText)
  1213  
  1214  type ErrorWriter int
  1215  
  1216  func (e ErrorWriter) Write(p []byte) (int, error) {
  1217  	return 0, alwaysError
  1218  }
  1219  
  1220  func TestExecuteGivesExecError(t *testing.T) {
  1221  	// First, a non-execution error shouldn't be an ExecError.
  1222  	tmpl, err := New("X").Parse("hello")
  1223  	if err != nil {
  1224  		t.Fatal(err)
  1225  	}
  1226  	err = tmpl.Execute(ErrorWriter(0), 0)
  1227  	if err == nil {
  1228  		t.Fatal("expected error; got none")
  1229  	}
  1230  	if err.Error() != alwaysErrorText {
  1231  		t.Errorf("expected %q error; got %q", alwaysErrorText, err)
  1232  	}
  1233  	// This one should be an ExecError.
  1234  	tmpl, err = New("X").Parse("hello, {{.X.Y}}")
  1235  	if err != nil {
  1236  		t.Fatal(err)
  1237  	}
  1238  	err = tmpl.Execute(ioutil.Discard, 0)
  1239  	if err == nil {
  1240  		t.Fatal("expected error; got none")
  1241  	}
  1242  	eerr, ok := err.(ExecError)
  1243  	if !ok {
  1244  		t.Fatalf("did not expect ExecError %s", eerr)
  1245  	}
  1246  	expect := "field X in type int"
  1247  	if !strings.Contains(err.Error(), expect) {
  1248  		t.Errorf("expected %q; got %q", expect, err)
  1249  	}
  1250  }
  1251  
  1252  func funcNameTestFunc() int {
  1253  	return 0
  1254  }
  1255  
  1256  func TestGoodFuncNames(t *testing.T) {
  1257  	names := []string{
  1258  		"_",
  1259  		"a",
  1260  		"a1",
  1261  		"a1",
  1262  		"Ӵ",
  1263  	}
  1264  	for _, name := range names {
  1265  		tmpl := New("X").Funcs(
  1266  			FuncMap{
  1267  				name: funcNameTestFunc,
  1268  			},
  1269  		)
  1270  		if tmpl == nil {
  1271  			t.Fatalf("nil result for %q", name)
  1272  		}
  1273  	}
  1274  }
  1275  
  1276  func TestBadFuncNames(t *testing.T) {
  1277  	names := []string{
  1278  		"",
  1279  		"2",
  1280  		"a-b",
  1281  	}
  1282  	for _, name := range names {
  1283  		testBadFuncName(name, t)
  1284  	}
  1285  }
  1286  
  1287  func testBadFuncName(name string, t *testing.T) {
  1288  	t.Helper()
  1289  	defer func() {
  1290  		recover()
  1291  	}()
  1292  	New("X").Funcs(
  1293  		FuncMap{
  1294  			name: funcNameTestFunc,
  1295  		},
  1296  	)
  1297  	// If we get here, the name did not cause a panic, which is how Funcs
  1298  	// reports an error.
  1299  	t.Errorf("%q succeeded incorrectly as function name", name)
  1300  }
  1301  
  1302  func TestBlock(t *testing.T) {
  1303  	const (
  1304  		input   = `a({{block "inner" .}}bar({{.}})baz{{end}})b`
  1305  		want    = `a(bar(hello)baz)b`
  1306  		overlay = `{{define "inner"}}foo({{.}})bar{{end}}`
  1307  		want2   = `a(foo(goodbye)bar)b`
  1308  	)
  1309  	tmpl, err := New("outer").Parse(input)
  1310  	if err != nil {
  1311  		t.Fatal(err)
  1312  	}
  1313  	tmpl2, err := Must(tmpl.Clone()).Parse(overlay)
  1314  	if err != nil {
  1315  		t.Fatal(err)
  1316  	}
  1317  
  1318  	var buf bytes.Buffer
  1319  	if err := tmpl.Execute(&buf, "hello"); err != nil {
  1320  		t.Fatal(err)
  1321  	}
  1322  	if got := buf.String(); got != want {
  1323  		t.Errorf("got %q, want %q", got, want)
  1324  	}
  1325  
  1326  	buf.Reset()
  1327  	if err := tmpl2.Execute(&buf, "goodbye"); err != nil {
  1328  		t.Fatal(err)
  1329  	}
  1330  	if got := buf.String(); got != want2 {
  1331  		t.Errorf("got %q, want %q", got, want2)
  1332  	}
  1333  }
  1334  
  1335  // Check that calling an invalid field on nil pointer prints
  1336  // a field error instead of a distracting nil pointer error.
  1337  // https://golang.org/issue/15125
  1338  func TestMissingFieldOnNil(t *testing.T) {
  1339  	tmpl := Must(New("tmpl").Parse("{{.MissingField}}"))
  1340  	var d *T
  1341  	err := tmpl.Execute(ioutil.Discard, d)
  1342  	got := "<nil>"
  1343  	if err != nil {
  1344  		got = err.Error()
  1345  	}
  1346  	want := "can't evaluate field MissingField in type *template.T"
  1347  	if !strings.HasSuffix(got, want) {
  1348  		t.Errorf("got error %q, want %q", got, want)
  1349  	}
  1350  }
  1351  
  1352  func TestMaxExecDepth(t *testing.T) {
  1353  	tmpl := Must(New("tmpl").Parse(`{{template "tmpl" .}}`))
  1354  	err := tmpl.Execute(ioutil.Discard, nil)
  1355  	got := "<nil>"
  1356  	if err != nil {
  1357  		got = err.Error()
  1358  	}
  1359  	const want = "exceeded maximum template depth"
  1360  	if !strings.Contains(got, want) {
  1361  		t.Errorf("got error %q; want %q", got, want)
  1362  	}
  1363  }
  1364  
  1365  func TestAddrOfIndex(t *testing.T) {
  1366  	// golang.org/issue/14916.
  1367  	// Before index worked on reflect.Values, the .String could not be
  1368  	// found on the (incorrectly unaddressable) V value,
  1369  	// in contrast to range, which worked fine.
  1370  	// Also testing that passing a reflect.Value to tmpl.Execute works.
  1371  	texts := []string{
  1372  		`{{range .}}{{.String}}{{end}}`,
  1373  		`{{with index . 0}}{{.String}}{{end}}`,
  1374  	}
  1375  	for _, text := range texts {
  1376  		tmpl := Must(New("tmpl").Parse(text))
  1377  		var buf bytes.Buffer
  1378  		err := tmpl.Execute(&buf, reflect.ValueOf([]V{{1}}))
  1379  		if err != nil {
  1380  			t.Fatalf("%s: Execute: %v", text, err)
  1381  		}
  1382  		if buf.String() != "<1>" {
  1383  			t.Fatalf("%s: template output = %q, want %q", text, &buf, "<1>")
  1384  		}
  1385  	}
  1386  }
  1387  
  1388  func TestInterfaceValues(t *testing.T) {
  1389  	// golang.org/issue/17714.
  1390  	// Before index worked on reflect.Values, interface values
  1391  	// were always implicitly promoted to the underlying value,
  1392  	// except that nil interfaces were promoted to the zero reflect.Value.
  1393  	// Eliminating a round trip to interface{} and back to reflect.Value
  1394  	// eliminated this promotion, breaking these cases.
  1395  	tests := []struct {
  1396  		text string
  1397  		out  string
  1398  	}{
  1399  		{`{{index .Nil 1}}`, "ERROR: index of untyped nil"},
  1400  		{`{{index .Slice 2}}`, "2"},
  1401  		{`{{index .Slice .Two}}`, "2"},
  1402  		{`{{call .Nil 1}}`, "ERROR: call of nil"},
  1403  		{`{{call .PlusOne 1}}`, "2"},
  1404  		{`{{call .PlusOne .One}}`, "2"},
  1405  		{`{{and (index .Slice 0) true}}`, "0"},
  1406  		{`{{and .Zero true}}`, "0"},
  1407  		{`{{and (index .Slice 1) false}}`, "false"},
  1408  		{`{{and .One false}}`, "false"},
  1409  		{`{{or (index .Slice 0) false}}`, "false"},
  1410  		{`{{or .Zero false}}`, "false"},
  1411  		{`{{or (index .Slice 1) true}}`, "1"},
  1412  		{`{{or .One true}}`, "1"},
  1413  		{`{{not (index .Slice 0)}}`, "true"},
  1414  		{`{{not .Zero}}`, "true"},
  1415  		{`{{not (index .Slice 1)}}`, "false"},
  1416  		{`{{not .One}}`, "false"},
  1417  		{`{{eq (index .Slice 0) .Zero}}`, "true"},
  1418  		{`{{eq (index .Slice 1) .One}}`, "true"},
  1419  		{`{{ne (index .Slice 0) .Zero}}`, "false"},
  1420  		{`{{ne (index .Slice 1) .One}}`, "false"},
  1421  		{`{{ge (index .Slice 0) .One}}`, "false"},
  1422  		{`{{ge (index .Slice 1) .Zero}}`, "true"},
  1423  		{`{{gt (index .Slice 0) .One}}`, "false"},
  1424  		{`{{gt (index .Slice 1) .Zero}}`, "true"},
  1425  		{`{{le (index .Slice 0) .One}}`, "true"},
  1426  		{`{{le (index .Slice 1) .Zero}}`, "false"},
  1427  		{`{{lt (index .Slice 0) .One}}`, "true"},
  1428  		{`{{lt (index .Slice 1) .Zero}}`, "false"},
  1429  	}
  1430  
  1431  	for _, tt := range tests {
  1432  		tmpl := Must(New("tmpl").Parse(tt.text))
  1433  		var buf bytes.Buffer
  1434  		err := tmpl.Execute(&buf, map[string]interface{}{
  1435  			"PlusOne": func(n int) int {
  1436  				return n + 1
  1437  			},
  1438  			"Slice": []int{0, 1, 2, 3},
  1439  			"One":   1,
  1440  			"Two":   2,
  1441  			"Nil":   nil,
  1442  			"Zero":  0,
  1443  		})
  1444  		if strings.HasPrefix(tt.out, "ERROR:") {
  1445  			e := strings.TrimSpace(strings.TrimPrefix(tt.out, "ERROR:"))
  1446  			if err == nil || !strings.Contains(err.Error(), e) {
  1447  				t.Errorf("%s: Execute: %v, want error %q", tt.text, err, e)
  1448  			}
  1449  			continue
  1450  		}
  1451  		if err != nil {
  1452  			t.Errorf("%s: Execute: %v", tt.text, err)
  1453  			continue
  1454  		}
  1455  		if buf.String() != tt.out {
  1456  			t.Errorf("%s: template output = %q, want %q", tt.text, &buf, tt.out)
  1457  		}
  1458  	}
  1459  }
  1460  
  1461  // Check that panics during calls are recovered and returned as errors.
  1462  func TestExecutePanicDuringCall(t *testing.T) {
  1463  	funcs := map[string]interface{}{
  1464  		"doPanic": func() string {
  1465  			panic("custom panic string")
  1466  		},
  1467  	}
  1468  	tests := []struct {
  1469  		name    string
  1470  		input   string
  1471  		data    interface{}
  1472  		wantErr string
  1473  	}{
  1474  		{
  1475  			"direct func call panics",
  1476  			"{{doPanic}}", (*T)(nil),
  1477  			`template: t:1:2: executing "t" at <doPanic>: error calling doPanic: custom panic string`,
  1478  		},
  1479  		{
  1480  			"indirect func call panics",
  1481  			"{{call doPanic}}", (*T)(nil),
  1482  			`template: t:1:7: executing "t" at <doPanic>: error calling doPanic: custom panic string`,
  1483  		},
  1484  		{
  1485  			"direct method call panics",
  1486  			"{{.GetU}}", (*T)(nil),
  1487  			`template: t:1:2: executing "t" at <.GetU>: error calling GetU: runtime error: invalid memory address or nil pointer dereference`,
  1488  		},
  1489  		{
  1490  			"indirect method call panics",
  1491  			"{{call .GetU}}", (*T)(nil),
  1492  			`template: t:1:7: executing "t" at <.GetU>: error calling GetU: runtime error: invalid memory address or nil pointer dereference`,
  1493  		},
  1494  		{
  1495  			"func field call panics",
  1496  			"{{call .PanicFunc}}", tVal,
  1497  			`template: t:1:2: executing "t" at <call .PanicFunc>: error calling call: test panic`,
  1498  		},
  1499  		{
  1500  			"method call on nil interface",
  1501  			"{{.NonEmptyInterfaceNil.Method0}}", tVal,
  1502  			`template: t:1:23: executing "t" at <.NonEmptyInterfaceNil.Method0>: nil pointer evaluating template.I.Method0`,
  1503  		},
  1504  	}
  1505  	for _, tc := range tests {
  1506  		b := new(bytes.Buffer)
  1507  		tmpl, err := New("t").Funcs(funcs).Parse(tc.input)
  1508  		if err != nil {
  1509  			t.Fatalf("parse error: %s", err)
  1510  		}
  1511  		err = tmpl.Execute(b, tc.data)
  1512  		if err == nil {
  1513  			t.Errorf("%s: expected error; got none", tc.name)
  1514  		} else if !strings.Contains(err.Error(), tc.wantErr) {
  1515  			if *debug {
  1516  				fmt.Printf("%s: test execute error: %s\n", tc.name, err)
  1517  			}
  1518  			t.Errorf("%s: expected error:\n%s\ngot:\n%s", tc.name, tc.wantErr, err)
  1519  		}
  1520  	}
  1521  }
  1522  

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