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"
    13  	"reflect"
    14  	"strings"
    15  	"sync"
    16  	"testing"
    17  )
    18  
    19  var debug = flag.Bool("debug", false, "show the errors produced by the tests")
    20  
    21  // T has lots of interesting pieces to use to test execution.
    22  type T struct {
    23  	// Basics
    24  	True        bool
    25  	I           int
    26  	U16         uint16
    27  	X, S        string
    28  	FloatZero   float64
    29  	ComplexZero complex128
    30  	// Nested structs.
    31  	U *U
    32  	// Struct with String method.
    33  	V0     V
    34  	V1, V2 *V
    35  	// Struct with Error method.
    36  	W0     W
    37  	W1, W2 *W
    38  	// Slices
    39  	SI      []int
    40  	SICap   []int
    41  	SIEmpty []int
    42  	SB      []bool
    43  	// Arrays
    44  	AI [3]int
    45  	// Maps
    46  	MSI      map[string]int
    47  	MSIone   map[string]int // one element, for deterministic output
    48  	MSIEmpty map[string]int
    49  	MXI      map[any]int
    50  	MII      map[int]int
    51  	MI32S    map[int32]string
    52  	MI64S    map[int64]string
    53  	MUI32S   map[uint32]string
    54  	MUI64S   map[uint64]string
    55  	MI8S     map[int8]string
    56  	MUI8S    map[uint8]string
    57  	SMSI     []map[string]int
    58  	// Empty interfaces; used to see if we can dig inside one.
    59  	Empty0 any // nil
    60  	Empty1 any
    61  	Empty2 any
    62  	Empty3 any
    63  	Empty4 any
    64  	// Non-empty interfaces.
    65  	NonEmptyInterface         I
    66  	NonEmptyInterfacePtS      *I
    67  	NonEmptyInterfaceNil      I
    68  	NonEmptyInterfaceTypedNil I
    69  	// Stringer.
    70  	Str fmt.Stringer
    71  	Err error
    72  	// Pointers
    73  	PI  *int
    74  	PS  *string
    75  	PSI *[]int
    76  	NIL *int
    77  	// Function (not method)
    78  	BinaryFunc      func(string, string) string
    79  	VariadicFunc    func(...string) string
    80  	VariadicFuncInt func(int, ...string) string
    81  	NilOKFunc       func(*int) bool
    82  	ErrFunc         func() (string, error)
    83  	PanicFunc       func() string
    84  	// Template to test evaluation of templates.
    85  	Tmpl *Template
    86  	// Unexported field; cannot be accessed by template.
    87  	unexported int
    88  }
    89  
    90  type S []string
    91  
    92  func (S) Method0() string {
    93  	return "M0"
    94  }
    95  
    96  type U struct {
    97  	V string
    98  }
    99  
   100  type V struct {
   101  	j int
   102  }
   103  
   104  func (v *V) String() string {
   105  	if v == nil {
   106  		return "nilV"
   107  	}
   108  	return fmt.Sprintf("<%d>", v.j)
   109  }
   110  
   111  type W struct {
   112  	k int
   113  }
   114  
   115  func (w *W) Error() string {
   116  	if w == nil {
   117  		return "nilW"
   118  	}
   119  	return fmt.Sprintf("[%d]", w.k)
   120  }
   121  
   122  var siVal = I(S{"a", "b"})
   123  
   124  var tVal = &T{
   125  	True:   true,
   126  	I:      17,
   127  	U16:    16,
   128  	X:      "x",
   129  	S:      "xyz",
   130  	U:      &U{"v"},
   131  	V0:     V{6666},
   132  	V1:     &V{7777}, // leave V2 as nil
   133  	W0:     W{888},
   134  	W1:     &W{999}, // leave W2 as nil
   135  	SI:     []int{3, 4, 5},
   136  	SICap:  make([]int, 5, 10),
   137  	AI:     [3]int{3, 4, 5},
   138  	SB:     []bool{true, false},
   139  	MSI:    map[string]int{"one": 1, "two": 2, "three": 3},
   140  	MSIone: map[string]int{"one": 1},
   141  	MXI:    map[any]int{"one": 1},
   142  	MII:    map[int]int{1: 1},
   143  	MI32S:  map[int32]string{1: "one", 2: "two"},
   144  	MI64S:  map[int64]string{2: "i642", 3: "i643"},
   145  	MUI32S: map[uint32]string{2: "u322", 3: "u323"},
   146  	MUI64S: map[uint64]string{2: "ui642", 3: "ui643"},
   147  	MI8S:   map[int8]string{2: "i82", 3: "i83"},
   148  	MUI8S:  map[uint8]string{2: "u82", 3: "u83"},
   149  	SMSI: []map[string]int{
   150  		{"one": 1, "two": 2},
   151  		{"eleven": 11, "twelve": 12},
   152  	},
   153  	Empty1:                    3,
   154  	Empty2:                    "empty2",
   155  	Empty3:                    []int{7, 8},
   156  	Empty4:                    &U{"UinEmpty"},
   157  	NonEmptyInterface:         &T{X: "x"},
   158  	NonEmptyInterfacePtS:      &siVal,
   159  	NonEmptyInterfaceTypedNil: (*T)(nil),
   160  	Str:                       bytes.NewBuffer([]byte("foozle")),
   161  	Err:                       errors.New("erroozle"),
   162  	PI:                        newInt(23),
   163  	PS:                        newString("a string"),
   164  	PSI:                       newIntSlice(21, 22, 23),
   165  	BinaryFunc:                func(a, b string) string { return fmt.Sprintf("[%s=%s]", a, b) },
   166  	VariadicFunc:              func(s ...string) string { return fmt.Sprint("<", strings.Join(s, "+"), ">") },
   167  	VariadicFuncInt:           func(a int, s ...string) string { return fmt.Sprint(a, "=<", strings.Join(s, "+"), ">") },
   168  	NilOKFunc:                 func(s *int) bool { return s == nil },
   169  	ErrFunc:                   func() (string, error) { return "bla", nil },
   170  	PanicFunc:                 func() string { panic("test panic") },
   171  	Tmpl:                      Must(New("x").Parse("test template")), // "x" is the value of .X
   172  }
   173  
   174  var tSliceOfNil = []*T{nil}
   175  
   176  // A non-empty interface.
   177  type I interface {
   178  	Method0() string
   179  }
   180  
   181  var iVal I = tVal
   182  
   183  // Helpers for creation.
   184  func newInt(n int) *int {
   185  	return &n
   186  }
   187  
   188  func newString(s string) *string {
   189  	return &s
   190  }
   191  
   192  func newIntSlice(n ...int) *[]int {
   193  	p := new([]int)
   194  	*p = make([]int, len(n))
   195  	copy(*p, n)
   196  	return p
   197  }
   198  
   199  // Simple methods with and without arguments.
   200  func (t *T) Method0() string {
   201  	return "M0"
   202  }
   203  
   204  func (t *T) Method1(a int) int {
   205  	return a
   206  }
   207  
   208  func (t *T) Method2(a uint16, b string) string {
   209  	return fmt.Sprintf("Method2: %d %s", a, b)
   210  }
   211  
   212  func (t *T) Method3(v any) string {
   213  	return fmt.Sprintf("Method3: %v", v)
   214  }
   215  
   216  func (t *T) Copy() *T {
   217  	n := new(T)
   218  	*n = *t
   219  	return n
   220  }
   221  
   222  func (t *T) MAdd(a int, b []int) []int {
   223  	v := make([]int, len(b))
   224  	for i, x := range b {
   225  		v[i] = x + a
   226  	}
   227  	return v
   228  }
   229  
   230  var myError = errors.New("my error")
   231  
   232  // MyError returns a value and an error according to its argument.
   233  func (t *T) MyError(error bool) (bool, error) {
   234  	if error {
   235  		return true, myError
   236  	}
   237  	return false, nil
   238  }
   239  
   240  // A few methods to test chaining.
   241  func (t *T) GetU() *U {
   242  	return t.U
   243  }
   244  
   245  func (u *U) TrueFalse(b bool) string {
   246  	if b {
   247  		return "true"
   248  	}
   249  	return ""
   250  }
   251  
   252  func typeOf(arg any) string {
   253  	return fmt.Sprintf("%T", arg)
   254  }
   255  
   256  type execTest struct {
   257  	name   string
   258  	input  string
   259  	output string
   260  	data   any
   261  	ok     bool
   262  }
   263  
   264  // bigInt and bigUint are hex string representing numbers either side
   265  // of the max int boundary.
   266  // We do it this way so the test doesn't depend on ints being 32 bits.
   267  var (
   268  	bigInt  = fmt.Sprintf("0x%x", int(1<<uint(reflect.TypeFor[int]().Bits()-1)-1))
   269  	bigUint = fmt.Sprintf("0x%x", uint(1<<uint(reflect.TypeFor[int]().Bits()-1)))
   270  )
   271  
   272  var execTests = []execTest{
   273  	// Trivial cases.
   274  	{"empty", "", "", nil, true},
   275  	{"text", "some text", "some text", nil, true},
   276  	{"nil action", "{{nil}}", "", nil, false},
   277  
   278  	// Ideal constants.
   279  	{"ideal int", "{{typeOf 3}}", "int", 0, true},
   280  	{"ideal float", "{{typeOf 1.0}}", "float64", 0, true},
   281  	{"ideal exp float", "{{typeOf 1e1}}", "float64", 0, true},
   282  	{"ideal complex", "{{typeOf 1i}}", "complex128", 0, true},
   283  	{"ideal int", "{{typeOf " + bigInt + "}}", "int", 0, true},
   284  	{"ideal too big", "{{typeOf " + bigUint + "}}", "", 0, false},
   285  	{"ideal nil without type", "{{nil}}", "", 0, false},
   286  
   287  	// Fields of structs.
   288  	{".X", "-{{.X}}-", "-x-", tVal, true},
   289  	{".U.V", "-{{.U.V}}-", "-v-", tVal, true},
   290  	{".unexported", "{{.unexported}}", "", tVal, false},
   291  
   292  	// Fields on maps.
   293  	{"map .one", "{{.MSI.one}}", "1", tVal, true},
   294  	{"map .two", "{{.MSI.two}}", "2", tVal, true},
   295  	{"map .NO", "{{.MSI.NO}}", "<no value>", tVal, true},
   296  	{"map .one interface", "{{.MXI.one}}", "1", tVal, true},
   297  	{"map .WRONG args", "{{.MSI.one 1}}", "", tVal, false},
   298  	{"map .WRONG type", "{{.MII.one}}", "", tVal, false},
   299  
   300  	// Dots of all kinds to test basic evaluation.
   301  	{"dot int", "<{{.}}>", "<13>", 13, true},
   302  	{"dot uint", "<{{.}}>", "<14>", uint(14), true},
   303  	{"dot float", "<{{.}}>", "<15.1>", 15.1, true},
   304  	{"dot bool", "<{{.}}>", "<true>", true, true},
   305  	{"dot complex", "<{{.}}>", "<(16.2-17i)>", 16.2 - 17i, true},
   306  	{"dot string", "<{{.}}>", "<hello>", "hello", true},
   307  	{"dot slice", "<{{.}}>", "<[-1 -2 -3]>", []int{-1, -2, -3}, true},
   308  	{"dot map", "<{{.}}>", "<map[two:22]>", map[string]int{"two": 22}, true},
   309  	{"dot struct", "<{{.}}>", "<{7 seven}>", struct {
   310  		a int
   311  		b string
   312  	}{7, "seven"}, true},
   313  
   314  	// Variables.
   315  	{"$ int", "{{$}}", "123", 123, true},
   316  	{"$.I", "{{$.I}}", "17", tVal, true},
   317  	{"$.U.V", "{{$.U.V}}", "v", tVal, true},
   318  	{"declare in action", "{{$x := $.U.V}}{{$x}}", "v", tVal, true},
   319  	{"simple assignment", "{{$x := 2}}{{$x = 3}}{{$x}}", "3", tVal, true},
   320  	{"nested assignment",
   321  		"{{$x := 2}}{{if true}}{{$x = 3}}{{end}}{{$x}}",
   322  		"3", tVal, true},
   323  	{"nested assignment changes the last declaration",
   324  		"{{$x := 1}}{{if true}}{{$x := 2}}{{if true}}{{$x = 3}}{{end}}{{end}}{{$x}}",
   325  		"1", tVal, true},
   326  
   327  	// Type with String method.
   328  	{"V{6666}.String()", "-{{.V0}}-", "-<6666>-", tVal, true},
   329  	{"&V{7777}.String()", "-{{.V1}}-", "-<7777>-", tVal, true},
   330  	{"(*V)(nil).String()", "-{{.V2}}-", "-nilV-", tVal, true},
   331  
   332  	// Type with Error method.
   333  	{"W{888}.Error()", "-{{.W0}}-", "-[888]-", tVal, true},
   334  	{"&W{999}.Error()", "-{{.W1}}-", "-[999]-", tVal, true},
   335  	{"(*W)(nil).Error()", "-{{.W2}}-", "-nilW-", tVal, true},
   336  
   337  	// Pointers.
   338  	{"*int", "{{.PI}}", "23", tVal, true},
   339  	{"*string", "{{.PS}}", "a string", tVal, true},
   340  	{"*[]int", "{{.PSI}}", "[21 22 23]", tVal, true},
   341  	{"*[]int[1]", "{{index .PSI 1}}", "22", tVal, true},
   342  	{"NIL", "{{.NIL}}", "<nil>", tVal, true},
   343  
   344  	// Empty interfaces holding values.
   345  	{"empty nil", "{{.Empty0}}", "<no value>", tVal, true},
   346  	{"empty with int", "{{.Empty1}}", "3", tVal, true},
   347  	{"empty with string", "{{.Empty2}}", "empty2", tVal, true},
   348  	{"empty with slice", "{{.Empty3}}", "[7 8]", tVal, true},
   349  	{"empty with struct", "{{.Empty4}}", "{UinEmpty}", tVal, true},
   350  	{"empty with struct, field", "{{.Empty4.V}}", "UinEmpty", tVal, true},
   351  
   352  	// Edge cases with <no value> with an interface value
   353  	{"field on interface", "{{.foo}}", "<no value>", nil, true},
   354  	{"field on parenthesized interface", "{{(.).foo}}", "<no value>", nil, true},
   355  
   356  	// Issue 31810: Parenthesized first element of pipeline with arguments.
   357  	// See also TestIssue31810.
   358  	{"unparenthesized non-function", "{{1 2}}", "", nil, false},
   359  	{"parenthesized non-function", "{{(1) 2}}", "", nil, false},
   360  	{"parenthesized non-function with no args", "{{(1)}}", "1", nil, true}, // This is fine.
   361  
   362  	// Method calls.
   363  	{".Method0", "-{{.Method0}}-", "-M0-", tVal, true},
   364  	{".Method1(1234)", "-{{.Method1 1234}}-", "-1234-", tVal, true},
   365  	{".Method1(.I)", "-{{.Method1 .I}}-", "-17-", tVal, true},
   366  	{".Method2(3, .X)", "-{{.Method2 3 .X}}-", "-Method2: 3 x-", tVal, true},
   367  	{".Method2(.U16, `str`)", "-{{.Method2 .U16 `str`}}-", "-Method2: 16 str-", tVal, true},
   368  	{".Method2(.U16, $x)", "{{if $x := .X}}-{{.Method2 .U16 $x}}{{end}}-", "-Method2: 16 x-", tVal, true},
   369  	{".Method3(nil constant)", "-{{.Method3 nil}}-", "-Method3: <nil>-", tVal, true},
   370  	{".Method3(nil value)", "-{{.Method3 .MXI.unset}}-", "-Method3: <nil>-", tVal, true},
   371  	{"method on var", "{{if $x := .}}-{{$x.Method2 .U16 $x.X}}{{end}}-", "-Method2: 16 x-", tVal, true},
   372  	{"method on chained var",
   373  		"{{range .MSIone}}{{if $.U.TrueFalse $.True}}{{$.U.TrueFalse $.True}}{{else}}WRONG{{end}}{{end}}",
   374  		"true", tVal, true},
   375  	{"chained method",
   376  		"{{range .MSIone}}{{if $.GetU.TrueFalse $.True}}{{$.U.TrueFalse $.True}}{{else}}WRONG{{end}}{{end}}",
   377  		"true", tVal, true},
   378  	{"chained method on variable",
   379  		"{{with $x := .}}{{with .SI}}{{$.GetU.TrueFalse $.True}}{{end}}{{end}}",
   380  		"true", tVal, true},
   381  	{".NilOKFunc not nil", "{{call .NilOKFunc .PI}}", "false", tVal, true},
   382  	{".NilOKFunc nil", "{{call .NilOKFunc nil}}", "true", tVal, true},
   383  	{"method on nil value from slice", "-{{range .}}{{.Method1 1234}}{{end}}-", "-1234-", tSliceOfNil, true},
   384  	{"method on typed nil interface value", "{{.NonEmptyInterfaceTypedNil.Method0}}", "M0", tVal, true},
   385  
   386  	// Function call builtin.
   387  	{".BinaryFunc", "{{call .BinaryFunc `1` `2`}}", "[1=2]", tVal, true},
   388  	{".VariadicFunc0", "{{call .VariadicFunc}}", "<>", tVal, true},
   389  	{".VariadicFunc2", "{{call .VariadicFunc `he` `llo`}}", "<he+llo>", tVal, true},
   390  	{".VariadicFuncInt", "{{call .VariadicFuncInt 33 `he` `llo`}}", "33=<he+llo>", tVal, true},
   391  	{"if .BinaryFunc call", "{{ if .BinaryFunc}}{{call .BinaryFunc `1` `2`}}{{end}}", "[1=2]", tVal, true},
   392  	{"if not .BinaryFunc call", "{{ if not .BinaryFunc}}{{call .BinaryFunc `1` `2`}}{{else}}No{{end}}", "No", tVal, true},
   393  	{"Interface Call", `{{stringer .S}}`, "foozle", map[string]any{"S": bytes.NewBufferString("foozle")}, true},
   394  	{".ErrFunc", "{{call .ErrFunc}}", "bla", tVal, true},
   395  	{"call nil", "{{call nil}}", "", tVal, false},
   396  
   397  	// Erroneous function calls (check args).
   398  	{".BinaryFuncTooFew", "{{call .BinaryFunc `1`}}", "", tVal, false},
   399  	{".BinaryFuncTooMany", "{{call .BinaryFunc `1` `2` `3`}}", "", tVal, false},
   400  	{".BinaryFuncBad0", "{{call .BinaryFunc 1 3}}", "", tVal, false},
   401  	{".BinaryFuncBad1", "{{call .BinaryFunc `1` 3}}", "", tVal, false},
   402  	{".VariadicFuncBad0", "{{call .VariadicFunc 3}}", "", tVal, false},
   403  	{".VariadicFuncIntBad0", "{{call .VariadicFuncInt}}", "", tVal, false},
   404  	{".VariadicFuncIntBad`", "{{call .VariadicFuncInt `x`}}", "", tVal, false},
   405  	{".VariadicFuncNilBad", "{{call .VariadicFunc nil}}", "", tVal, false},
   406  
   407  	// Pipelines.
   408  	{"pipeline", "-{{.Method0 | .Method2 .U16}}-", "-Method2: 16 M0-", tVal, true},
   409  	{"pipeline func", "-{{call .VariadicFunc `llo` | call .VariadicFunc `he` }}-", "-<he+<llo>>-", tVal, true},
   410  
   411  	// Nil values aren't missing arguments.
   412  	{"nil pipeline", "{{ .Empty0 | call .NilOKFunc }}", "true", tVal, true},
   413  	{"nil call arg", "{{ call .NilOKFunc .Empty0 }}", "true", tVal, true},
   414  	{"bad nil pipeline", "{{ .Empty0 | .VariadicFunc }}", "", tVal, false},
   415  
   416  	// Parenthesized expressions
   417  	{"parens in pipeline", "{{printf `%d %d %d` (1) (2 | add 3) (add 4 (add 5 6))}}", "1 5 15", tVal, true},
   418  
   419  	// Parenthesized expressions with field accesses
   420  	{"parens: $ in paren", "{{($).X}}", "x", tVal, true},
   421  	{"parens: $.GetU in paren", "{{($.GetU).V}}", "v", tVal, true},
   422  	{"parens: $ in paren in pipe", "{{($ | echo).X}}", "x", tVal, true},
   423  	{"parens: spaces and args", `{{(makemap "up" "down" "left" "right").left}}`, "right", tVal, true},
   424  
   425  	// If.
   426  	{"if true", "{{if true}}TRUE{{end}}", "TRUE", tVal, true},
   427  	{"if false", "{{if false}}TRUE{{else}}FALSE{{end}}", "FALSE", tVal, true},
   428  	{"if nil", "{{if nil}}TRUE{{end}}", "", tVal, false},
   429  	{"if on typed nil interface value", "{{if .NonEmptyInterfaceTypedNil}}TRUE{{ end }}", "", tVal, true},
   430  	{"if 1", "{{if 1}}NON-ZERO{{else}}ZERO{{end}}", "NON-ZERO", tVal, true},
   431  	{"if 0", "{{if 0}}NON-ZERO{{else}}ZERO{{end}}", "ZERO", tVal, true},
   432  	{"if 1.5", "{{if 1.5}}NON-ZERO{{else}}ZERO{{end}}", "NON-ZERO", tVal, true},
   433  	{"if 0.0", "{{if .FloatZero}}NON-ZERO{{else}}ZERO{{end}}", "ZERO", tVal, true},
   434  	{"if 1.5i", "{{if 1.5i}}NON-ZERO{{else}}ZERO{{end}}", "NON-ZERO", tVal, true},
   435  	{"if 0.0i", "{{if .ComplexZero}}NON-ZERO{{else}}ZERO{{end}}", "ZERO", tVal, true},
   436  	{"if emptystring", "{{if ``}}NON-EMPTY{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
   437  	{"if string", "{{if `notempty`}}NON-EMPTY{{else}}EMPTY{{end}}", "NON-EMPTY", tVal, true},
   438  	{"if emptyslice", "{{if .SIEmpty}}NON-EMPTY{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
   439  	{"if slice", "{{if .SI}}NON-EMPTY{{else}}EMPTY{{end}}", "NON-EMPTY", tVal, true},
   440  	{"if emptymap", "{{if .MSIEmpty}}NON-EMPTY{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
   441  	{"if map", "{{if .MSI}}NON-EMPTY{{else}}EMPTY{{end}}", "NON-EMPTY", tVal, true},
   442  	{"if map unset", "{{if .MXI.none}}NON-ZERO{{else}}ZERO{{end}}", "ZERO", tVal, true},
   443  	{"if map not unset", "{{if not .MXI.none}}ZERO{{else}}NON-ZERO{{end}}", "ZERO", tVal, true},
   444  	{"if $x with $y int", "{{if $x := true}}{{with $y := .I}}{{$x}},{{$y}}{{end}}{{end}}", "true,17", tVal, true},
   445  	{"if $x with $x int", "{{if $x := true}}{{with $x := .I}}{{$x}},{{end}}{{$x}}{{end}}", "17,true", tVal, true},
   446  	{"if else if", "{{if false}}FALSE{{else if true}}TRUE{{end}}", "TRUE", tVal, true},
   447  	{"if else chain", "{{if eq 1 3}}1{{else if eq 2 3}}2{{else if eq 3 3}}3{{end}}", "3", tVal, true},
   448  
   449  	// Print etc.
   450  	{"print", `{{print "hello, print"}}`, "hello, print", tVal, true},
   451  	{"print 123", `{{print 1 2 3}}`, "1 2 3", tVal, true},
   452  	{"print nil", `{{print nil}}`, "<nil>", tVal, true},
   453  	{"println", `{{println 1 2 3}}`, "1 2 3\n", tVal, true},
   454  	{"printf int", `{{printf "%04x" 127}}`, "007f", tVal, true},
   455  	{"printf float", `{{printf "%g" 3.5}}`, "3.5", tVal, true},
   456  	{"printf complex", `{{printf "%g" 1+7i}}`, "(1+7i)", tVal, true},
   457  	{"printf string", `{{printf "%s" "hello"}}`, "hello", tVal, true},
   458  	{"printf function", `{{printf "%#q" zeroArgs}}`, "`zeroArgs`", tVal, true},
   459  	{"printf field", `{{printf "%s" .U.V}}`, "v", tVal, true},
   460  	{"printf method", `{{printf "%s" .Method0}}`, "M0", tVal, true},
   461  	{"printf dot", `{{with .I}}{{printf "%d" .}}{{end}}`, "17", tVal, true},
   462  	{"printf var", `{{with $x := .I}}{{printf "%d" $x}}{{end}}`, "17", tVal, true},
   463  	{"printf lots", `{{printf "%d %s %g %s" 127 "hello" 7-3i .Method0}}`, "127 hello (7-3i) M0", tVal, true},
   464  
   465  	// HTML.
   466  	{"html", `{{html "<script>alert(\"XSS\");</script>"}}`,
   467  		"&lt;script&gt;alert(&#34;XSS&#34;);&lt;/script&gt;", nil, true},
   468  	{"html pipeline", `{{printf "<script>alert(\"XSS\");</script>" | html}}`,
   469  		"&lt;script&gt;alert(&#34;XSS&#34;);&lt;/script&gt;", nil, true},
   470  	{"html", `{{html .PS}}`, "a string", tVal, true},
   471  	{"html typed nil", `{{html .NIL}}`, "&lt;nil&gt;", tVal, true},
   472  	{"html untyped nil", `{{html .Empty0}}`, "&lt;no value&gt;", tVal, true},
   473  
   474  	// JavaScript.
   475  	{"js", `{{js .}}`, `It\'d be nice.`, `It'd be nice.`, true},
   476  
   477  	// URL query.
   478  	{"urlquery", `{{"http://www.example.org/"|urlquery}}`, "http%3A%2F%2Fwww.example.org%2F", nil, true},
   479  
   480  	// Booleans
   481  	{"not", "{{not true}} {{not false}}", "false true", nil, true},
   482  	{"and", "{{and false 0}} {{and 1 0}} {{and 0 true}} {{and 1 1}}", "false 0 0 1", nil, true},
   483  	{"or", "{{or 0 0}} {{or 1 0}} {{or 0 true}} {{or 1 1}}", "0 1 true 1", nil, true},
   484  	{"or short-circuit", "{{or 0 1 (die)}}", "1", nil, true},
   485  	{"and short-circuit", "{{and 1 0 (die)}}", "0", nil, true},
   486  	{"or short-circuit2", "{{or 0 0 (die)}}", "", nil, false},
   487  	{"and short-circuit2", "{{and 1 1 (die)}}", "", nil, false},
   488  	{"and pipe-true", "{{1 | and 1}}", "1", nil, true},
   489  	{"and pipe-false", "{{0 | and 1}}", "0", nil, true},
   490  	{"or pipe-true", "{{1 | or 0}}", "1", nil, true},
   491  	{"or pipe-false", "{{0 | or 0}}", "0", nil, true},
   492  	{"and undef", "{{and 1 .Unknown}}", "<no value>", nil, true},
   493  	{"or undef", "{{or 0 .Unknown}}", "<no value>", nil, true},
   494  	{"boolean if", "{{if and true 1 `hi`}}TRUE{{else}}FALSE{{end}}", "TRUE", tVal, true},
   495  	{"boolean if not", "{{if and true 1 `hi` | not}}TRUE{{else}}FALSE{{end}}", "FALSE", nil, true},
   496  	{"boolean if pipe", "{{if true | not | and 1}}TRUE{{else}}FALSE{{end}}", "FALSE", nil, true},
   497  
   498  	// Indexing.
   499  	{"slice[0]", "{{index .SI 0}}", "3", tVal, true},
   500  	{"slice[1]", "{{index .SI 1}}", "4", tVal, true},
   501  	{"slice[HUGE]", "{{index .SI 10}}", "", tVal, false},
   502  	{"slice[WRONG]", "{{index .SI `hello`}}", "", tVal, false},
   503  	{"slice[nil]", "{{index .SI nil}}", "", tVal, false},
   504  	{"map[one]", "{{index .MSI `one`}}", "1", tVal, true},
   505  	{"map[two]", "{{index .MSI `two`}}", "2", tVal, true},
   506  	{"map[NO]", "{{index .MSI `XXX`}}", "0", tVal, true},
   507  	{"map[nil]", "{{index .MSI nil}}", "", tVal, false},
   508  	{"map[``]", "{{index .MSI ``}}", "0", tVal, true},
   509  	{"map[WRONG]", "{{index .MSI 10}}", "", tVal, false},
   510  	{"double index", "{{index .SMSI 1 `eleven`}}", "11", tVal, true},
   511  	{"nil[1]", "{{index nil 1}}", "", tVal, false},
   512  	{"map MI64S", "{{index .MI64S 2}}", "i642", tVal, true},
   513  	{"map MI32S", "{{index .MI32S 2}}", "two", tVal, true},
   514  	{"map MUI64S", "{{index .MUI64S 3}}", "ui643", tVal, true},
   515  	{"map MI8S", "{{index .MI8S 3}}", "i83", tVal, true},
   516  	{"map MUI8S", "{{index .MUI8S 2}}", "u82", tVal, true},
   517  	{"index of an interface field", "{{index .Empty3 0}}", "7", tVal, true},
   518  
   519  	// Slicing.
   520  	{"slice[:]", "{{slice .SI}}", "[3 4 5]", tVal, true},
   521  	{"slice[1:]", "{{slice .SI 1}}", "[4 5]", tVal, true},
   522  	{"slice[1:2]", "{{slice .SI 1 2}}", "[4]", tVal, true},
   523  	{"slice[-1:]", "{{slice .SI -1}}", "", tVal, false},
   524  	{"slice[1:-2]", "{{slice .SI 1 -2}}", "", tVal, false},
   525  	{"slice[1:2:-1]", "{{slice .SI 1 2 -1}}", "", tVal, false},
   526  	{"slice[2:1]", "{{slice .SI 2 1}}", "", tVal, false},
   527  	{"slice[2:2:1]", "{{slice .SI 2 2 1}}", "", tVal, false},
   528  	{"out of range", "{{slice .SI 4 5}}", "", tVal, false},
   529  	{"out of range", "{{slice .SI 2 2 5}}", "", tVal, false},
   530  	{"len(s) < indexes < cap(s)", "{{slice .SICap 6 10}}", "[0 0 0 0]", tVal, true},
   531  	{"len(s) < indexes < cap(s)", "{{slice .SICap 6 10 10}}", "[0 0 0 0]", tVal, true},
   532  	{"indexes > cap(s)", "{{slice .SICap 10 11}}", "", tVal, false},
   533  	{"indexes > cap(s)", "{{slice .SICap 6 10 11}}", "", tVal, false},
   534  	{"array[:]", "{{slice .AI}}", "[3 4 5]", tVal, true},
   535  	{"array[1:]", "{{slice .AI 1}}", "[4 5]", tVal, true},
   536  	{"array[1:2]", "{{slice .AI 1 2}}", "[4]", tVal, true},
   537  	{"string[:]", "{{slice .S}}", "xyz", tVal, true},
   538  	{"string[0:1]", "{{slice .S 0 1}}", "x", tVal, true},
   539  	{"string[1:]", "{{slice .S 1}}", "yz", tVal, true},
   540  	{"string[1:2]", "{{slice .S 1 2}}", "y", tVal, true},
   541  	{"out of range", "{{slice .S 1 5}}", "", tVal, false},
   542  	{"3-index slice of string", "{{slice .S 1 2 2}}", "", tVal, false},
   543  	{"slice of an interface field", "{{slice .Empty3 0 1}}", "[7]", tVal, true},
   544  
   545  	// Len.
   546  	{"slice", "{{len .SI}}", "3", tVal, true},
   547  	{"map", "{{len .MSI }}", "3", tVal, true},
   548  	{"len of int", "{{len 3}}", "", tVal, false},
   549  	{"len of nothing", "{{len .Empty0}}", "", tVal, false},
   550  	{"len of an interface field", "{{len .Empty3}}", "2", tVal, true},
   551  
   552  	// With.
   553  	{"with true", "{{with true}}{{.}}{{end}}", "true", tVal, true},
   554  	{"with false", "{{with false}}{{.}}{{else}}FALSE{{end}}", "FALSE", tVal, true},
   555  	{"with 1", "{{with 1}}{{.}}{{else}}ZERO{{end}}", "1", tVal, true},
   556  	{"with 0", "{{with 0}}{{.}}{{else}}ZERO{{end}}", "ZERO", tVal, true},
   557  	{"with 1.5", "{{with 1.5}}{{.}}{{else}}ZERO{{end}}", "1.5", tVal, true},
   558  	{"with 0.0", "{{with .FloatZero}}{{.}}{{else}}ZERO{{end}}", "ZERO", tVal, true},
   559  	{"with 1.5i", "{{with 1.5i}}{{.}}{{else}}ZERO{{end}}", "(0+1.5i)", tVal, true},
   560  	{"with 0.0i", "{{with .ComplexZero}}{{.}}{{else}}ZERO{{end}}", "ZERO", tVal, true},
   561  	{"with emptystring", "{{with ``}}{{.}}{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
   562  	{"with string", "{{with `notempty`}}{{.}}{{else}}EMPTY{{end}}", "notempty", tVal, true},
   563  	{"with emptyslice", "{{with .SIEmpty}}{{.}}{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
   564  	{"with slice", "{{with .SI}}{{.}}{{else}}EMPTY{{end}}", "[3 4 5]", tVal, true},
   565  	{"with emptymap", "{{with .MSIEmpty}}{{.}}{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
   566  	{"with map", "{{with .MSIone}}{{.}}{{else}}EMPTY{{end}}", "map[one:1]", tVal, true},
   567  	{"with empty interface, struct field", "{{with .Empty4}}{{.V}}{{end}}", "UinEmpty", tVal, true},
   568  	{"with $x int", "{{with $x := .I}}{{$x}}{{end}}", "17", tVal, true},
   569  	{"with $x struct.U.V", "{{with $x := $}}{{$x.U.V}}{{end}}", "v", tVal, true},
   570  	{"with variable and action", "{{with $x := $}}{{$y := $.U.V}}{{$y}}{{end}}", "v", tVal, true},
   571  	{"with on typed nil interface value", "{{with .NonEmptyInterfaceTypedNil}}TRUE{{ end }}", "", tVal, true},
   572  
   573  	// Range.
   574  	{"range []int", "{{range .SI}}-{{.}}-{{end}}", "-3--4--5-", tVal, true},
   575  	{"range empty no else", "{{range .SIEmpty}}-{{.}}-{{end}}", "", tVal, true},
   576  	{"range []int else", "{{range .SI}}-{{.}}-{{else}}EMPTY{{end}}", "-3--4--5-", tVal, true},
   577  	{"range empty else", "{{range .SIEmpty}}-{{.}}-{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
   578  	{"range []int break else", "{{range .SI}}-{{.}}-{{break}}NOTREACHED{{else}}EMPTY{{end}}", "-3-", tVal, true},
   579  	{"range []int continue else", "{{range .SI}}-{{.}}-{{continue}}NOTREACHED{{else}}EMPTY{{end}}", "-3--4--5-", tVal, true},
   580  	{"range []bool", "{{range .SB}}-{{.}}-{{end}}", "-true--false-", tVal, true},
   581  	{"range []int method", "{{range .SI | .MAdd .I}}-{{.}}-{{end}}", "-20--21--22-", tVal, true},
   582  	{"range map", "{{range .MSI}}-{{.}}-{{end}}", "-1--3--2-", tVal, true},
   583  	{"range empty map no else", "{{range .MSIEmpty}}-{{.}}-{{end}}", "", tVal, true},
   584  	{"range map else", "{{range .MSI}}-{{.}}-{{else}}EMPTY{{end}}", "-1--3--2-", tVal, true},
   585  	{"range empty map else", "{{range .MSIEmpty}}-{{.}}-{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
   586  	{"range empty interface", "{{range .Empty3}}-{{.}}-{{else}}EMPTY{{end}}", "-7--8-", tVal, true},
   587  	{"range empty nil", "{{range .Empty0}}-{{.}}-{{end}}", "", tVal, true},
   588  	{"range $x SI", "{{range $x := .SI}}<{{$x}}>{{end}}", "<3><4><5>", tVal, true},
   589  	{"range $x $y SI", "{{range $x, $y := .SI}}<{{$x}}={{$y}}>{{end}}", "<0=3><1=4><2=5>", tVal, true},
   590  	{"range $x MSIone", "{{range $x := .MSIone}}<{{$x}}>{{end}}", "<1>", tVal, true},
   591  	{"range $x $y MSIone", "{{range $x, $y := .MSIone}}<{{$x}}={{$y}}>{{end}}", "<one=1>", tVal, true},
   592  	{"range $x PSI", "{{range $x := .PSI}}<{{$x}}>{{end}}", "<21><22><23>", tVal, true},
   593  	{"declare in range", "{{range $x := .PSI}}<{{$foo:=$x}}{{$x}}>{{end}}", "<21><22><23>", tVal, true},
   594  	{"range count", `{{range $i, $x := count 5}}[{{$i}}]{{$x}}{{end}}`, "[0]a[1]b[2]c[3]d[4]e", tVal, true},
   595  	{"range nil count", `{{range $i, $x := count 0}}{{else}}empty{{end}}`, "empty", tVal, true},
   596  
   597  	// Cute examples.
   598  	{"or as if true", `{{or .SI "slice is empty"}}`, "[3 4 5]", tVal, true},
   599  	{"or as if false", `{{or .SIEmpty "slice is empty"}}`, "slice is empty", tVal, true},
   600  
   601  	// Error handling.
   602  	{"error method, error", "{{.MyError true}}", "", tVal, false},
   603  	{"error method, no error", "{{.MyError false}}", "false", tVal, true},
   604  
   605  	// Numbers
   606  	{"decimal", "{{print 1234}}", "1234", tVal, true},
   607  	{"decimal _", "{{print 12_34}}", "1234", tVal, true},
   608  	{"binary", "{{print 0b101}}", "5", tVal, true},
   609  	{"binary _", "{{print 0b_1_0_1}}", "5", tVal, true},
   610  	{"BINARY", "{{print 0B101}}", "5", tVal, true},
   611  	{"octal0", "{{print 0377}}", "255", tVal, true},
   612  	{"octal", "{{print 0o377}}", "255", tVal, true},
   613  	{"octal _", "{{print 0o_3_7_7}}", "255", tVal, true},
   614  	{"OCTAL", "{{print 0O377}}", "255", tVal, true},
   615  	{"hex", "{{print 0x123}}", "291", tVal, true},
   616  	{"hex _", "{{print 0x1_23}}", "291", tVal, true},
   617  	{"HEX", "{{print 0X123ABC}}", "1194684", tVal, true},
   618  	{"float", "{{print 123.4}}", "123.4", tVal, true},
   619  	{"float _", "{{print 0_0_1_2_3.4}}", "123.4", tVal, true},
   620  	{"hex float", "{{print +0x1.ep+2}}", "7.5", tVal, true},
   621  	{"hex float _", "{{print +0x_1.e_0p+0_2}}", "7.5", tVal, true},
   622  	{"HEX float", "{{print +0X1.EP+2}}", "7.5", tVal, true},
   623  	{"print multi", "{{print 1_2_3_4 7.5_00_00_00}}", "1234 7.5", tVal, true},
   624  	{"print multi2", "{{print 1234 0x0_1.e_0p+02}}", "1234 7.5", tVal, true},
   625  
   626  	// Fixed bugs.
   627  	// Must separate dot and receiver; otherwise args are evaluated with dot set to variable.
   628  	{"bug0", "{{range .MSIone}}{{if $.Method1 .}}X{{end}}{{end}}", "X", tVal, true},
   629  	// Do not loop endlessly in indirect for non-empty interfaces.
   630  	// The bug appears with *interface only; looped forever.
   631  	{"bug1", "{{.Method0}}", "M0", &iVal, true},
   632  	// Was taking address of interface field, so method set was empty.
   633  	{"bug2", "{{$.NonEmptyInterface.Method0}}", "M0", tVal, true},
   634  	// Struct values were not legal in with - mere oversight.
   635  	{"bug3", "{{with $}}{{.Method0}}{{end}}", "M0", tVal, true},
   636  	// Nil interface values in if.
   637  	{"bug4", "{{if .Empty0}}non-nil{{else}}nil{{end}}", "nil", tVal, true},
   638  	// Stringer.
   639  	{"bug5", "{{.Str}}", "foozle", tVal, true},
   640  	{"bug5a", "{{.Err}}", "erroozle", tVal, true},
   641  	// Args need to be indirected and dereferenced sometimes.
   642  	{"bug6a", "{{vfunc .V0 .V1}}", "vfunc", tVal, true},
   643  	{"bug6b", "{{vfunc .V0 .V0}}", "vfunc", tVal, true},
   644  	{"bug6c", "{{vfunc .V1 .V0}}", "vfunc", tVal, true},
   645  	{"bug6d", "{{vfunc .V1 .V1}}", "vfunc", tVal, true},
   646  	// Legal parse but illegal execution: non-function should have no arguments.
   647  	{"bug7a", "{{3 2}}", "", tVal, false},
   648  	{"bug7b", "{{$x := 1}}{{$x 2}}", "", tVal, false},
   649  	{"bug7c", "{{$x := 1}}{{3 | $x}}", "", tVal, false},
   650  	// Pipelined arg was not being type-checked.
   651  	{"bug8a", "{{3|oneArg}}", "", tVal, false},
   652  	{"bug8b", "{{4|dddArg 3}}", "", tVal, false},
   653  	// A bug was introduced that broke map lookups for lower-case names.
   654  	{"bug9", "{{.cause}}", "neglect", map[string]string{"cause": "neglect"}, true},
   655  	// Field chain starting with function did not work.
   656  	{"bug10", "{{mapOfThree.three}}-{{(mapOfThree).three}}", "3-3", 0, true},
   657  	// Dereferencing nil pointer while evaluating function arguments should not panic. Issue 7333.
   658  	{"bug11", "{{valueString .PS}}", "", T{}, false},
   659  	// 0xef gave constant type float64. Issue 8622.
   660  	{"bug12xe", "{{printf `%T` 0xef}}", "int", T{}, true},
   661  	{"bug12xE", "{{printf `%T` 0xEE}}", "int", T{}, true},
   662  	{"bug12Xe", "{{printf `%T` 0Xef}}", "int", T{}, true},
   663  	{"bug12XE", "{{printf `%T` 0XEE}}", "int", T{}, true},
   664  	// Chained nodes did not work as arguments. Issue 8473.
   665  	{"bug13", "{{print (.Copy).I}}", "17", tVal, true},
   666  	// Didn't protect against nil or literal values in field chains.
   667  	{"bug14a", "{{(nil).True}}", "", tVal, false},
   668  	{"bug14b", "{{$x := nil}}{{$x.anything}}", "", tVal, false},
   669  	{"bug14c", `{{$x := (1.0)}}{{$y := ("hello")}}{{$x.anything}}{{$y.true}}`, "", tVal, false},
   670  	// Didn't call validateType on function results. Issue 10800.
   671  	{"bug15", "{{valueString returnInt}}", "", tVal, false},
   672  	// Variadic function corner cases. Issue 10946.
   673  	{"bug16a", "{{true|printf}}", "", tVal, false},
   674  	{"bug16b", "{{1|printf}}", "", tVal, false},
   675  	{"bug16c", "{{1.1|printf}}", "", tVal, false},
   676  	{"bug16d", "{{'x'|printf}}", "", tVal, false},
   677  	{"bug16e", "{{0i|printf}}", "", tVal, false},
   678  	{"bug16f", "{{true|twoArgs \"xxx\"}}", "", tVal, false},
   679  	{"bug16g", "{{\"aaa\" |twoArgs \"bbb\"}}", "twoArgs=bbbaaa", tVal, true},
   680  	{"bug16h", "{{1|oneArg}}", "", tVal, false},
   681  	{"bug16i", "{{\"aaa\"|oneArg}}", "oneArg=aaa", tVal, true},
   682  	{"bug16j", "{{1+2i|printf \"%v\"}}", "(1+2i)", tVal, true},
   683  	{"bug16k", "{{\"aaa\"|printf }}", "aaa", tVal, true},
   684  	{"bug17a", "{{.NonEmptyInterface.X}}", "x", tVal, true},
   685  	{"bug17b", "-{{.NonEmptyInterface.Method1 1234}}-", "-1234-", tVal, true},
   686  	{"bug17c", "{{len .NonEmptyInterfacePtS}}", "2", tVal, true},
   687  	{"bug17d", "{{index .NonEmptyInterfacePtS 0}}", "a", tVal, true},
   688  	{"bug17e", "{{range .NonEmptyInterfacePtS}}-{{.}}-{{end}}", "-a--b-", tVal, true},
   689  
   690  	// More variadic function corner cases. Some runes would get evaluated
   691  	// as constant floats instead of ints. Issue 34483.
   692  	{"bug18a", "{{eq . '.'}}", "true", '.', true},
   693  	{"bug18b", "{{eq . 'e'}}", "true", 'e', true},
   694  	{"bug18c", "{{eq . 'P'}}", "true", 'P', true},
   695  
   696  	{"issue56490", "{{$i := 0}}{{$x := 0}}{{range $i = .AI}}{{end}}{{$i}}", "5", tVal, true},
   697  	{"issue60801", "{{$k := 0}}{{$v := 0}}{{range $k, $v = .AI}}{{$k}}={{$v}} {{end}}", "0=3 1=4 2=5 ", tVal, true},
   698  }
   699  
   700  func zeroArgs() string {
   701  	return "zeroArgs"
   702  }
   703  
   704  func oneArg(a string) string {
   705  	return "oneArg=" + a
   706  }
   707  
   708  func twoArgs(a, b string) string {
   709  	return "twoArgs=" + a + b
   710  }
   711  
   712  func dddArg(a int, b ...string) string {
   713  	return fmt.Sprintln(a, b)
   714  }
   715  
   716  // count returns a channel that will deliver n sequential 1-letter strings starting at "a"
   717  func count(n int) chan string {
   718  	if n == 0 {
   719  		return nil
   720  	}
   721  	c := make(chan string)
   722  	go func() {
   723  		for i := 0; i < n; i++ {
   724  			c <- "abcdefghijklmnop"[i : i+1]
   725  		}
   726  		close(c)
   727  	}()
   728  	return c
   729  }
   730  
   731  // vfunc takes a *V and a V
   732  func vfunc(V, *V) string {
   733  	return "vfunc"
   734  }
   735  
   736  // valueString takes a string, not a pointer.
   737  func valueString(v string) string {
   738  	return "value is ignored"
   739  }
   740  
   741  // returnInt returns an int
   742  func returnInt() int {
   743  	return 7
   744  }
   745  
   746  func add(args ...int) int {
   747  	sum := 0
   748  	for _, x := range args {
   749  		sum += x
   750  	}
   751  	return sum
   752  }
   753  
   754  func echo(arg any) any {
   755  	return arg
   756  }
   757  
   758  func makemap(arg ...string) map[string]string {
   759  	if len(arg)%2 != 0 {
   760  		panic("bad makemap")
   761  	}
   762  	m := make(map[string]string)
   763  	for i := 0; i < len(arg); i += 2 {
   764  		m[arg[i]] = arg[i+1]
   765  	}
   766  	return m
   767  }
   768  
   769  func stringer(s fmt.Stringer) string {
   770  	return s.String()
   771  }
   772  
   773  func mapOfThree() any {
   774  	return map[string]int{"three": 3}
   775  }
   776  
   777  func testExecute(execTests []execTest, template *Template, t *testing.T) {
   778  	b := new(strings.Builder)
   779  	funcs := FuncMap{
   780  		"add":         add,
   781  		"count":       count,
   782  		"dddArg":      dddArg,
   783  		"die":         func() bool { panic("die") },
   784  		"echo":        echo,
   785  		"makemap":     makemap,
   786  		"mapOfThree":  mapOfThree,
   787  		"oneArg":      oneArg,
   788  		"returnInt":   returnInt,
   789  		"stringer":    stringer,
   790  		"twoArgs":     twoArgs,
   791  		"typeOf":      typeOf,
   792  		"valueString": valueString,
   793  		"vfunc":       vfunc,
   794  		"zeroArgs":    zeroArgs,
   795  	}
   796  	for _, test := range execTests {
   797  		var tmpl *Template
   798  		var err error
   799  		if template == nil {
   800  			tmpl, err = New(test.name).Funcs(funcs).Parse(test.input)
   801  		} else {
   802  			tmpl, err = template.New(test.name).Funcs(funcs).Parse(test.input)
   803  		}
   804  		if err != nil {
   805  			t.Errorf("%s: parse error: %s", test.name, err)
   806  			continue
   807  		}
   808  		b.Reset()
   809  		err = tmpl.Execute(b, test.data)
   810  		switch {
   811  		case !test.ok && err == nil:
   812  			t.Errorf("%s: expected error; got none", test.name)
   813  			continue
   814  		case test.ok && err != nil:
   815  			t.Errorf("%s: unexpected execute error: %s", test.name, err)
   816  			continue
   817  		case !test.ok && err != nil:
   818  			// expected error, got one
   819  			if *debug {
   820  				fmt.Printf("%s: %s\n\t%s\n", test.name, test.input, err)
   821  			}
   822  		}
   823  		result := b.String()
   824  		if result != test.output {
   825  			t.Errorf("%s: expected\n\t%q\ngot\n\t%q", test.name, test.output, result)
   826  		}
   827  	}
   828  }
   829  
   830  func TestExecute(t *testing.T) {
   831  	testExecute(execTests, nil, t)
   832  }
   833  
   834  var delimPairs = []string{
   835  	"", "", // default
   836  	"{{", "}}", // same as default
   837  	"<<", ">>", // distinct
   838  	"|", "|", // same
   839  	"(日)", "(本)", // peculiar
   840  }
   841  
   842  func TestDelims(t *testing.T) {
   843  	const hello = "Hello, world"
   844  	var value = struct{ Str string }{hello}
   845  	for i := 0; i < len(delimPairs); i += 2 {
   846  		text := ".Str"
   847  		left := delimPairs[i+0]
   848  		trueLeft := left
   849  		right := delimPairs[i+1]
   850  		trueRight := right
   851  		if left == "" { // default case
   852  			trueLeft = "{{"
   853  		}
   854  		if right == "" { // default case
   855  			trueRight = "}}"
   856  		}
   857  		text = trueLeft + text + trueRight
   858  		// Now add a comment
   859  		text += trueLeft + "/*comment*/" + trueRight
   860  		// Now add  an action containing a string.
   861  		text += trueLeft + `"` + trueLeft + `"` + trueRight
   862  		// At this point text looks like `{{.Str}}{{/*comment*/}}{{"{{"}}`.
   863  		tmpl, err := New("delims").Delims(left, right).Parse(text)
   864  		if err != nil {
   865  			t.Fatalf("delim %q text %q parse err %s", left, text, err)
   866  		}
   867  		var b = new(strings.Builder)
   868  		err = tmpl.Execute(b, value)
   869  		if err != nil {
   870  			t.Fatalf("delim %q exec err %s", left, err)
   871  		}
   872  		if b.String() != hello+trueLeft {
   873  			t.Errorf("expected %q got %q", hello+trueLeft, b.String())
   874  		}
   875  	}
   876  }
   877  
   878  // Check that an error from a method flows back to the top.
   879  func TestExecuteError(t *testing.T) {
   880  	b := new(bytes.Buffer)
   881  	tmpl := New("error")
   882  	_, err := tmpl.Parse("{{.MyError true}}")
   883  	if err != nil {
   884  		t.Fatalf("parse error: %s", err)
   885  	}
   886  	err = tmpl.Execute(b, tVal)
   887  	if err == nil {
   888  		t.Errorf("expected error; got none")
   889  	} else if !strings.Contains(err.Error(), myError.Error()) {
   890  		if *debug {
   891  			fmt.Printf("test execute error: %s\n", err)
   892  		}
   893  		t.Errorf("expected myError; got %s", err)
   894  	}
   895  }
   896  
   897  const execErrorText = `line 1
   898  line 2
   899  line 3
   900  {{template "one" .}}
   901  {{define "one"}}{{template "two" .}}{{end}}
   902  {{define "two"}}{{template "three" .}}{{end}}
   903  {{define "three"}}{{index "hi" $}}{{end}}`
   904  
   905  // Check that an error from a nested template contains all the relevant information.
   906  func TestExecError(t *testing.T) {
   907  	tmpl, err := New("top").Parse(execErrorText)
   908  	if err != nil {
   909  		t.Fatal("parse error:", err)
   910  	}
   911  	var b bytes.Buffer
   912  	err = tmpl.Execute(&b, 5) // 5 is out of range indexing "hi"
   913  	if err == nil {
   914  		t.Fatal("expected error")
   915  	}
   916  	const want = `template: top:7:20: executing "three" at <index "hi" $>: error calling index: index out of range: 5`
   917  	got := err.Error()
   918  	if got != want {
   919  		t.Errorf("expected\n%q\ngot\n%q", want, got)
   920  	}
   921  }
   922  
   923  type CustomError struct{}
   924  
   925  func (*CustomError) Error() string { return "heyo !" }
   926  
   927  // Check that a custom error can be returned.
   928  func TestExecError_CustomError(t *testing.T) {
   929  	failingFunc := func() (string, error) {
   930  		return "", &CustomError{}
   931  	}
   932  	tmpl := Must(New("top").Funcs(FuncMap{
   933  		"err": failingFunc,
   934  	}).Parse("{{ err }}"))
   935  
   936  	var b bytes.Buffer
   937  	err := tmpl.Execute(&b, nil)
   938  
   939  	var e *CustomError
   940  	if !errors.As(err, &e) {
   941  		t.Fatalf("expected custom error; got %s", err)
   942  	}
   943  }
   944  
   945  func TestJSEscaping(t *testing.T) {
   946  	testCases := []struct {
   947  		in, exp string
   948  	}{
   949  		{`a`, `a`},
   950  		{`'foo`, `\'foo`},
   951  		{`Go "jump" \`, `Go \"jump\" \\`},
   952  		{`Yukihiro says "今日は世界"`, `Yukihiro says \"今日は世界\"`},
   953  		{"unprintable \uFFFE", `unprintable \uFFFE`},
   954  		{`<html>`, `\u003Chtml\u003E`},
   955  		{`no = in attributes`, `no \u003D in attributes`},
   956  		{`&#x27; does not become HTML entity`, `\u0026#x27; does not become HTML entity`},
   957  	}
   958  	for _, tc := range testCases {
   959  		s := JSEscapeString(tc.in)
   960  		if s != tc.exp {
   961  			t.Errorf("JS escaping [%s] got [%s] want [%s]", tc.in, s, tc.exp)
   962  		}
   963  	}
   964  }
   965  
   966  // A nice example: walk a binary tree.
   967  
   968  type Tree struct {
   969  	Val         int
   970  	Left, Right *Tree
   971  }
   972  
   973  // Use different delimiters to test Set.Delims.
   974  // Also test the trimming of leading and trailing spaces.
   975  const treeTemplate = `
   976  	(- define "tree" -)
   977  	[
   978  		(- .Val -)
   979  		(- with .Left -)
   980  			(template "tree" . -)
   981  		(- end -)
   982  		(- with .Right -)
   983  			(- template "tree" . -)
   984  		(- end -)
   985  	]
   986  	(- end -)
   987  `
   988  
   989  func TestTree(t *testing.T) {
   990  	var tree = &Tree{
   991  		1,
   992  		&Tree{
   993  			2, &Tree{
   994  				3,
   995  				&Tree{
   996  					4, nil, nil,
   997  				},
   998  				nil,
   999  			},
  1000  			&Tree{
  1001  				5,
  1002  				&Tree{
  1003  					6, nil, nil,
  1004  				},
  1005  				nil,
  1006  			},
  1007  		},
  1008  		&Tree{
  1009  			7,
  1010  			&Tree{
  1011  				8,
  1012  				&Tree{
  1013  					9, nil, nil,
  1014  				},
  1015  				nil,
  1016  			},
  1017  			&Tree{
  1018  				10,
  1019  				&Tree{
  1020  					11, nil, nil,
  1021  				},
  1022  				nil,
  1023  			},
  1024  		},
  1025  	}
  1026  	tmpl, err := New("root").Delims("(", ")").Parse(treeTemplate)
  1027  	if err != nil {
  1028  		t.Fatal("parse error:", err)
  1029  	}
  1030  	var b strings.Builder
  1031  	const expect = "[1[2[3[4]][5[6]]][7[8[9]][10[11]]]]"
  1032  	// First by looking up the template.
  1033  	err = tmpl.Lookup("tree").Execute(&b, tree)
  1034  	if err != nil {
  1035  		t.Fatal("exec error:", err)
  1036  	}
  1037  	result := b.String()
  1038  	if result != expect {
  1039  		t.Errorf("expected %q got %q", expect, result)
  1040  	}
  1041  	// Then direct to execution.
  1042  	b.Reset()
  1043  	err = tmpl.ExecuteTemplate(&b, "tree", tree)
  1044  	if err != nil {
  1045  		t.Fatal("exec error:", err)
  1046  	}
  1047  	result = b.String()
  1048  	if result != expect {
  1049  		t.Errorf("expected %q got %q", expect, result)
  1050  	}
  1051  }
  1052  
  1053  func TestExecuteOnNewTemplate(t *testing.T) {
  1054  	// This is issue 3872.
  1055  	New("Name").Templates()
  1056  	// This is issue 11379.
  1057  	new(Template).Templates()
  1058  	new(Template).Parse("")
  1059  	new(Template).New("abc").Parse("")
  1060  	new(Template).Execute(nil, nil)                // returns an error (but does not crash)
  1061  	new(Template).ExecuteTemplate(nil, "XXX", nil) // returns an error (but does not crash)
  1062  }
  1063  
  1064  const testTemplates = `{{define "one"}}one{{end}}{{define "two"}}two{{end}}`
  1065  
  1066  func TestMessageForExecuteEmpty(t *testing.T) {
  1067  	// Test a truly empty template.
  1068  	tmpl := New("empty")
  1069  	var b bytes.Buffer
  1070  	err := tmpl.Execute(&b, 0)
  1071  	if err == nil {
  1072  		t.Fatal("expected initial error")
  1073  	}
  1074  	got := err.Error()
  1075  	want := `template: empty: "empty" is an incomplete or empty template`
  1076  	if got != want {
  1077  		t.Errorf("expected error %s got %s", want, got)
  1078  	}
  1079  	// Add a non-empty template to check that the error is helpful.
  1080  	tests, err := New("").Parse(testTemplates)
  1081  	if err != nil {
  1082  		t.Fatal(err)
  1083  	}
  1084  	tmpl.AddParseTree("secondary", tests.Tree)
  1085  	err = tmpl.Execute(&b, 0)
  1086  	if err == nil {
  1087  		t.Fatal("expected second error")
  1088  	}
  1089  	got = err.Error()
  1090  	want = `template: empty: "empty" is an incomplete or empty template`
  1091  	if got != want {
  1092  		t.Errorf("expected error %s got %s", want, got)
  1093  	}
  1094  	// Make sure we can execute the secondary.
  1095  	err = tmpl.ExecuteTemplate(&b, "secondary", 0)
  1096  	if err != nil {
  1097  		t.Fatal(err)
  1098  	}
  1099  }
  1100  
  1101  func TestFinalForPrintf(t *testing.T) {
  1102  	tmpl, err := New("").Parse(`{{"x" | printf}}`)
  1103  	if err != nil {
  1104  		t.Fatal(err)
  1105  	}
  1106  	var b bytes.Buffer
  1107  	err = tmpl.Execute(&b, 0)
  1108  	if err != nil {
  1109  		t.Fatal(err)
  1110  	}
  1111  }
  1112  
  1113  type cmpTest struct {
  1114  	expr  string
  1115  	truth string
  1116  	ok    bool
  1117  }
  1118  
  1119  var cmpTests = []cmpTest{
  1120  	{"eq true true", "true", true},
  1121  	{"eq true false", "false", true},
  1122  	{"eq 1+2i 1+2i", "true", true},
  1123  	{"eq 1+2i 1+3i", "false", true},
  1124  	{"eq 1.5 1.5", "true", true},
  1125  	{"eq 1.5 2.5", "false", true},
  1126  	{"eq 1 1", "true", true},
  1127  	{"eq 1 2", "false", true},
  1128  	{"eq `xy` `xy`", "true", true},
  1129  	{"eq `xy` `xyz`", "false", true},
  1130  	{"eq .Uthree .Uthree", "true", true},
  1131  	{"eq .Uthree .Ufour", "false", true},
  1132  	{"eq 3 4 5 6 3", "true", true},
  1133  	{"eq 3 4 5 6 7", "false", true},
  1134  	{"ne true true", "false", true},
  1135  	{"ne true false", "true", true},
  1136  	{"ne 1+2i 1+2i", "false", true},
  1137  	{"ne 1+2i 1+3i", "true", true},
  1138  	{"ne 1.5 1.5", "false", true},
  1139  	{"ne 1.5 2.5", "true", true},
  1140  	{"ne 1 1", "false", true},
  1141  	{"ne 1 2", "true", true},
  1142  	{"ne `xy` `xy`", "false", true},
  1143  	{"ne `xy` `xyz`", "true", true},
  1144  	{"ne .Uthree .Uthree", "false", true},
  1145  	{"ne .Uthree .Ufour", "true", true},
  1146  	{"lt 1.5 1.5", "false", true},
  1147  	{"lt 1.5 2.5", "true", true},
  1148  	{"lt 1 1", "false", true},
  1149  	{"lt 1 2", "true", true},
  1150  	{"lt `xy` `xy`", "false", true},
  1151  	{"lt `xy` `xyz`", "true", true},
  1152  	{"lt .Uthree .Uthree", "false", true},
  1153  	{"lt .Uthree .Ufour", "true", true},
  1154  	{"le 1.5 1.5", "true", true},
  1155  	{"le 1.5 2.5", "true", true},
  1156  	{"le 2.5 1.5", "false", true},
  1157  	{"le 1 1", "true", true},
  1158  	{"le 1 2", "true", true},
  1159  	{"le 2 1", "false", true},
  1160  	{"le `xy` `xy`", "true", true},
  1161  	{"le `xy` `xyz`", "true", true},
  1162  	{"le `xyz` `xy`", "false", true},
  1163  	{"le .Uthree .Uthree", "true", true},
  1164  	{"le .Uthree .Ufour", "true", true},
  1165  	{"le .Ufour .Uthree", "false", true},
  1166  	{"gt 1.5 1.5", "false", true},
  1167  	{"gt 1.5 2.5", "false", true},
  1168  	{"gt 1 1", "false", true},
  1169  	{"gt 2 1", "true", true},
  1170  	{"gt 1 2", "false", true},
  1171  	{"gt `xy` `xy`", "false", true},
  1172  	{"gt `xy` `xyz`", "false", true},
  1173  	{"gt .Uthree .Uthree", "false", true},
  1174  	{"gt .Uthree .Ufour", "false", true},
  1175  	{"gt .Ufour .Uthree", "true", true},
  1176  	{"ge 1.5 1.5", "true", true},
  1177  	{"ge 1.5 2.5", "false", true},
  1178  	{"ge 2.5 1.5", "true", true},
  1179  	{"ge 1 1", "true", true},
  1180  	{"ge 1 2", "false", true},
  1181  	{"ge 2 1", "true", true},
  1182  	{"ge `xy` `xy`", "true", true},
  1183  	{"ge `xy` `xyz`", "false", true},
  1184  	{"ge `xyz` `xy`", "true", true},
  1185  	{"ge .Uthree .Uthree", "true", true},
  1186  	{"ge .Uthree .Ufour", "false", true},
  1187  	{"ge .Ufour .Uthree", "true", true},
  1188  	// Mixing signed and unsigned integers.
  1189  	{"eq .Uthree .Three", "true", true},
  1190  	{"eq .Three .Uthree", "true", true},
  1191  	{"le .Uthree .Three", "true", true},
  1192  	{"le .Three .Uthree", "true", true},
  1193  	{"ge .Uthree .Three", "true", true},
  1194  	{"ge .Three .Uthree", "true", true},
  1195  	{"lt .Uthree .Three", "false", true},
  1196  	{"lt .Three .Uthree", "false", true},
  1197  	{"gt .Uthree .Three", "false", true},
  1198  	{"gt .Three .Uthree", "false", true},
  1199  	{"eq .Ufour .Three", "false", true},
  1200  	{"lt .Ufour .Three", "false", true},
  1201  	{"gt .Ufour .Three", "true", true},
  1202  	{"eq .NegOne .Uthree", "false", true},
  1203  	{"eq .Uthree .NegOne", "false", true},
  1204  	{"ne .NegOne .Uthree", "true", true},
  1205  	{"ne .Uthree .NegOne", "true", true},
  1206  	{"lt .NegOne .Uthree", "true", true},
  1207  	{"lt .Uthree .NegOne", "false", true},
  1208  	{"le .NegOne .Uthree", "true", true},
  1209  	{"le .Uthree .NegOne", "false", true},
  1210  	{"gt .NegOne .Uthree", "false", true},
  1211  	{"gt .Uthree .NegOne", "true", true},
  1212  	{"ge .NegOne .Uthree", "false", true},
  1213  	{"ge .Uthree .NegOne", "true", true},
  1214  	{"eq (index `x` 0) 'x'", "true", true}, // The example that triggered this rule.
  1215  	{"eq (index `x` 0) 'y'", "false", true},
  1216  	{"eq .V1 .V2", "true", true},
  1217  	{"eq .Ptr .Ptr", "true", true},
  1218  	{"eq .Ptr .NilPtr", "false", true},
  1219  	{"eq .NilPtr .NilPtr", "true", true},
  1220  	{"eq .Iface1 .Iface1", "true", true},
  1221  	{"eq .Iface1 .NilIface", "false", true},
  1222  	{"eq .NilIface .NilIface", "true", true},
  1223  	{"eq .NilIface .Iface1", "false", true},
  1224  	{"eq .NilIface 0", "false", true},
  1225  	{"eq 0 .NilIface", "false", true},
  1226  	{"eq .Map .Map", "true", true},        // Uncomparable types but nil is OK.
  1227  	{"eq .Map nil", "true", true},         // Uncomparable types but nil is OK.
  1228  	{"eq nil .Map", "true", true},         // Uncomparable types but nil is OK.
  1229  	{"eq .Map .NonNilMap", "false", true}, // Uncomparable types but nil is OK.
  1230  	// Errors
  1231  	{"eq `xy` 1", "", false},                // Different types.
  1232  	{"eq 2 2.0", "", false},                 // Different types.
  1233  	{"lt true true", "", false},             // Unordered types.
  1234  	{"lt 1+0i 1+0i", "", false},             // Unordered types.
  1235  	{"eq .Ptr 1", "", false},                // Incompatible types.
  1236  	{"eq .Ptr .NegOne", "", false},          // Incompatible types.
  1237  	{"eq .Map .V1", "", false},              // Uncomparable types.
  1238  	{"eq .NonNilMap .NonNilMap", "", false}, // Uncomparable types.
  1239  }
  1240  
  1241  func TestComparison(t *testing.T) {
  1242  	b := new(strings.Builder)
  1243  	var cmpStruct = struct {
  1244  		Uthree, Ufour    uint
  1245  		NegOne, Three    int
  1246  		Ptr, NilPtr      *int
  1247  		NonNilMap        map[int]int
  1248  		Map              map[int]int
  1249  		V1, V2           V
  1250  		Iface1, NilIface fmt.Stringer
  1251  	}{
  1252  		Uthree:    3,
  1253  		Ufour:     4,
  1254  		NegOne:    -1,
  1255  		Three:     3,
  1256  		Ptr:       new(int),
  1257  		NonNilMap: make(map[int]int),
  1258  		Iface1:    b,
  1259  	}
  1260  	for _, test := range cmpTests {
  1261  		text := fmt.Sprintf("{{if %s}}true{{else}}false{{end}}", test.expr)
  1262  		tmpl, err := New("empty").Parse(text)
  1263  		if err != nil {
  1264  			t.Fatalf("%q: %s", test.expr, err)
  1265  		}
  1266  		b.Reset()
  1267  		err = tmpl.Execute(b, &cmpStruct)
  1268  		if test.ok && err != nil {
  1269  			t.Errorf("%s errored incorrectly: %s", test.expr, err)
  1270  			continue
  1271  		}
  1272  		if !test.ok && err == nil {
  1273  			t.Errorf("%s did not error", test.expr)
  1274  			continue
  1275  		}
  1276  		if b.String() != test.truth {
  1277  			t.Errorf("%s: want %s; got %s", test.expr, test.truth, b.String())
  1278  		}
  1279  	}
  1280  }
  1281  
  1282  func TestMissingMapKey(t *testing.T) {
  1283  	data := map[string]int{
  1284  		"x": 99,
  1285  	}
  1286  	tmpl, err := New("t1").Parse("{{.x}} {{.y}}")
  1287  	if err != nil {
  1288  		t.Fatal(err)
  1289  	}
  1290  	var b strings.Builder
  1291  	// By default, just get "<no value>"
  1292  	err = tmpl.Execute(&b, data)
  1293  	if err != nil {
  1294  		t.Fatal(err)
  1295  	}
  1296  	want := "99 <no value>"
  1297  	got := b.String()
  1298  	if got != want {
  1299  		t.Errorf("got %q; expected %q", got, want)
  1300  	}
  1301  	// Same if we set the option explicitly to the default.
  1302  	tmpl.Option("missingkey=default")
  1303  	b.Reset()
  1304  	err = tmpl.Execute(&b, data)
  1305  	if err != nil {
  1306  		t.Fatal("default:", err)
  1307  	}
  1308  	want = "99 <no value>"
  1309  	got = b.String()
  1310  	if got != want {
  1311  		t.Errorf("got %q; expected %q", got, want)
  1312  	}
  1313  	// Next we ask for a zero value
  1314  	tmpl.Option("missingkey=zero")
  1315  	b.Reset()
  1316  	err = tmpl.Execute(&b, data)
  1317  	if err != nil {
  1318  		t.Fatal("zero:", err)
  1319  	}
  1320  	want = "99 0"
  1321  	got = b.String()
  1322  	if got != want {
  1323  		t.Errorf("got %q; expected %q", got, want)
  1324  	}
  1325  	// Now we ask for an error.
  1326  	tmpl.Option("missingkey=error")
  1327  	err = tmpl.Execute(&b, data)
  1328  	if err == nil {
  1329  		t.Errorf("expected error; got none")
  1330  	}
  1331  	// same Option, but now a nil interface: ask for an error
  1332  	err = tmpl.Execute(&b, nil)
  1333  	t.Log(err)
  1334  	if err == nil {
  1335  		t.Errorf("expected error for nil-interface; got none")
  1336  	}
  1337  }
  1338  
  1339  // Test that the error message for multiline unterminated string
  1340  // refers to the line number of the opening quote.
  1341  func TestUnterminatedStringError(t *testing.T) {
  1342  	_, err := New("X").Parse("hello\n\n{{`unterminated\n\n\n\n}}\n some more\n\n")
  1343  	if err == nil {
  1344  		t.Fatal("expected error")
  1345  	}
  1346  	str := err.Error()
  1347  	if !strings.Contains(str, "X:3: unterminated raw quoted string") {
  1348  		t.Fatalf("unexpected error: %s", str)
  1349  	}
  1350  }
  1351  
  1352  const alwaysErrorText = "always be failing"
  1353  
  1354  var alwaysError = errors.New(alwaysErrorText)
  1355  
  1356  type ErrorWriter int
  1357  
  1358  func (e ErrorWriter) Write(p []byte) (int, error) {
  1359  	return 0, alwaysError
  1360  }
  1361  
  1362  func TestExecuteGivesExecError(t *testing.T) {
  1363  	// First, a non-execution error shouldn't be an ExecError.
  1364  	tmpl, err := New("X").Parse("hello")
  1365  	if err != nil {
  1366  		t.Fatal(err)
  1367  	}
  1368  	err = tmpl.Execute(ErrorWriter(0), 0)
  1369  	if err == nil {
  1370  		t.Fatal("expected error; got none")
  1371  	}
  1372  	if err.Error() != alwaysErrorText {
  1373  		t.Errorf("expected %q error; got %q", alwaysErrorText, err)
  1374  	}
  1375  	// This one should be an ExecError.
  1376  	tmpl, err = New("X").Parse("hello, {{.X.Y}}")
  1377  	if err != nil {
  1378  		t.Fatal(err)
  1379  	}
  1380  	err = tmpl.Execute(io.Discard, 0)
  1381  	if err == nil {
  1382  		t.Fatal("expected error; got none")
  1383  	}
  1384  	eerr, ok := err.(ExecError)
  1385  	if !ok {
  1386  		t.Fatalf("did not expect ExecError %s", eerr)
  1387  	}
  1388  	expect := "field X in type int"
  1389  	if !strings.Contains(err.Error(), expect) {
  1390  		t.Errorf("expected %q; got %q", expect, err)
  1391  	}
  1392  }
  1393  
  1394  func funcNameTestFunc() int {
  1395  	return 0
  1396  }
  1397  
  1398  func TestGoodFuncNames(t *testing.T) {
  1399  	names := []string{
  1400  		"_",
  1401  		"a",
  1402  		"a1",
  1403  		"a1",
  1404  		"Ӵ",
  1405  	}
  1406  	for _, name := range names {
  1407  		tmpl := New("X").Funcs(
  1408  			FuncMap{
  1409  				name: funcNameTestFunc,
  1410  			},
  1411  		)
  1412  		if tmpl == nil {
  1413  			t.Fatalf("nil result for %q", name)
  1414  		}
  1415  	}
  1416  }
  1417  
  1418  func TestBadFuncNames(t *testing.T) {
  1419  	names := []string{
  1420  		"",
  1421  		"2",
  1422  		"a-b",
  1423  	}
  1424  	for _, name := range names {
  1425  		testBadFuncName(name, t)
  1426  	}
  1427  }
  1428  
  1429  func testBadFuncName(name string, t *testing.T) {
  1430  	t.Helper()
  1431  	defer func() {
  1432  		recover()
  1433  	}()
  1434  	New("X").Funcs(
  1435  		FuncMap{
  1436  			name: funcNameTestFunc,
  1437  		},
  1438  	)
  1439  	// If we get here, the name did not cause a panic, which is how Funcs
  1440  	// reports an error.
  1441  	t.Errorf("%q succeeded incorrectly as function name", name)
  1442  }
  1443  
  1444  func TestBlock(t *testing.T) {
  1445  	const (
  1446  		input   = `a({{block "inner" .}}bar({{.}})baz{{end}})b`
  1447  		want    = `a(bar(hello)baz)b`
  1448  		overlay = `{{define "inner"}}foo({{.}})bar{{end}}`
  1449  		want2   = `a(foo(goodbye)bar)b`
  1450  	)
  1451  	tmpl, err := New("outer").Parse(input)
  1452  	if err != nil {
  1453  		t.Fatal(err)
  1454  	}
  1455  	tmpl2, err := Must(tmpl.Clone()).Parse(overlay)
  1456  	if err != nil {
  1457  		t.Fatal(err)
  1458  	}
  1459  
  1460  	var buf strings.Builder
  1461  	if err := tmpl.Execute(&buf, "hello"); err != nil {
  1462  		t.Fatal(err)
  1463  	}
  1464  	if got := buf.String(); got != want {
  1465  		t.Errorf("got %q, want %q", got, want)
  1466  	}
  1467  
  1468  	buf.Reset()
  1469  	if err := tmpl2.Execute(&buf, "goodbye"); err != nil {
  1470  		t.Fatal(err)
  1471  	}
  1472  	if got := buf.String(); got != want2 {
  1473  		t.Errorf("got %q, want %q", got, want2)
  1474  	}
  1475  }
  1476  
  1477  func TestEvalFieldErrors(t *testing.T) {
  1478  	tests := []struct {
  1479  		name, src string
  1480  		value     any
  1481  		want      string
  1482  	}{
  1483  		{
  1484  			// Check that calling an invalid field on nil pointer
  1485  			// prints a field error instead of a distracting nil
  1486  			// pointer error. https://golang.org/issue/15125
  1487  			"MissingFieldOnNil",
  1488  			"{{.MissingField}}",
  1489  			(*T)(nil),
  1490  			"can't evaluate field MissingField in type *template.T",
  1491  		},
  1492  		{
  1493  			"MissingFieldOnNonNil",
  1494  			"{{.MissingField}}",
  1495  			&T{},
  1496  			"can't evaluate field MissingField in type *template.T",
  1497  		},
  1498  		{
  1499  			"ExistingFieldOnNil",
  1500  			"{{.X}}",
  1501  			(*T)(nil),
  1502  			"nil pointer evaluating *template.T.X",
  1503  		},
  1504  		{
  1505  			"MissingKeyOnNilMap",
  1506  			"{{.MissingKey}}",
  1507  			(*map[string]string)(nil),
  1508  			"nil pointer evaluating *map[string]string.MissingKey",
  1509  		},
  1510  		{
  1511  			"MissingKeyOnNilMapPtr",
  1512  			"{{.MissingKey}}",
  1513  			(*map[string]string)(nil),
  1514  			"nil pointer evaluating *map[string]string.MissingKey",
  1515  		},
  1516  		{
  1517  			"MissingKeyOnMapPtrToNil",
  1518  			"{{.MissingKey}}",
  1519  			&map[string]string{},
  1520  			"<nil>",
  1521  		},
  1522  	}
  1523  	for _, tc := range tests {
  1524  		t.Run(tc.name, func(t *testing.T) {
  1525  			tmpl := Must(New("tmpl").Parse(tc.src))
  1526  			err := tmpl.Execute(io.Discard, tc.value)
  1527  			got := "<nil>"
  1528  			if err != nil {
  1529  				got = err.Error()
  1530  			}
  1531  			if !strings.HasSuffix(got, tc.want) {
  1532  				t.Fatalf("got error %q, want %q", got, tc.want)
  1533  			}
  1534  		})
  1535  	}
  1536  }
  1537  
  1538  func TestMaxExecDepth(t *testing.T) {
  1539  	if testing.Short() {
  1540  		t.Skip("skipping in -short mode")
  1541  	}
  1542  	tmpl := Must(New("tmpl").Parse(`{{template "tmpl" .}}`))
  1543  	err := tmpl.Execute(io.Discard, nil)
  1544  	got := "<nil>"
  1545  	if err != nil {
  1546  		got = err.Error()
  1547  	}
  1548  	const want = "exceeded maximum template depth"
  1549  	if !strings.Contains(got, want) {
  1550  		t.Errorf("got error %q; want %q", got, want)
  1551  	}
  1552  }
  1553  
  1554  func TestAddrOfIndex(t *testing.T) {
  1555  	// golang.org/issue/14916.
  1556  	// Before index worked on reflect.Values, the .String could not be
  1557  	// found on the (incorrectly unaddressable) V value,
  1558  	// in contrast to range, which worked fine.
  1559  	// Also testing that passing a reflect.Value to tmpl.Execute works.
  1560  	texts := []string{
  1561  		`{{range .}}{{.String}}{{end}}`,
  1562  		`{{with index . 0}}{{.String}}{{end}}`,
  1563  	}
  1564  	for _, text := range texts {
  1565  		tmpl := Must(New("tmpl").Parse(text))
  1566  		var buf strings.Builder
  1567  		err := tmpl.Execute(&buf, reflect.ValueOf([]V{{1}}))
  1568  		if err != nil {
  1569  			t.Fatalf("%s: Execute: %v", text, err)
  1570  		}
  1571  		if buf.String() != "<1>" {
  1572  			t.Fatalf("%s: template output = %q, want %q", text, &buf, "<1>")
  1573  		}
  1574  	}
  1575  }
  1576  
  1577  func TestInterfaceValues(t *testing.T) {
  1578  	// golang.org/issue/17714.
  1579  	// Before index worked on reflect.Values, interface values
  1580  	// were always implicitly promoted to the underlying value,
  1581  	// except that nil interfaces were promoted to the zero reflect.Value.
  1582  	// Eliminating a round trip to interface{} and back to reflect.Value
  1583  	// eliminated this promotion, breaking these cases.
  1584  	tests := []struct {
  1585  		text string
  1586  		out  string
  1587  	}{
  1588  		{`{{index .Nil 1}}`, "ERROR: index of untyped nil"},
  1589  		{`{{index .Slice 2}}`, "2"},
  1590  		{`{{index .Slice .Two}}`, "2"},
  1591  		{`{{call .Nil 1}}`, "ERROR: call of nil"},
  1592  		{`{{call .PlusOne 1}}`, "2"},
  1593  		{`{{call .PlusOne .One}}`, "2"},
  1594  		{`{{and (index .Slice 0) true}}`, "0"},
  1595  		{`{{and .Zero true}}`, "0"},
  1596  		{`{{and (index .Slice 1) false}}`, "false"},
  1597  		{`{{and .One false}}`, "false"},
  1598  		{`{{or (index .Slice 0) false}}`, "false"},
  1599  		{`{{or .Zero false}}`, "false"},
  1600  		{`{{or (index .Slice 1) true}}`, "1"},
  1601  		{`{{or .One true}}`, "1"},
  1602  		{`{{not (index .Slice 0)}}`, "true"},
  1603  		{`{{not .Zero}}`, "true"},
  1604  		{`{{not (index .Slice 1)}}`, "false"},
  1605  		{`{{not .One}}`, "false"},
  1606  		{`{{eq (index .Slice 0) .Zero}}`, "true"},
  1607  		{`{{eq (index .Slice 1) .One}}`, "true"},
  1608  		{`{{ne (index .Slice 0) .Zero}}`, "false"},
  1609  		{`{{ne (index .Slice 1) .One}}`, "false"},
  1610  		{`{{ge (index .Slice 0) .One}}`, "false"},
  1611  		{`{{ge (index .Slice 1) .Zero}}`, "true"},
  1612  		{`{{gt (index .Slice 0) .One}}`, "false"},
  1613  		{`{{gt (index .Slice 1) .Zero}}`, "true"},
  1614  		{`{{le (index .Slice 0) .One}}`, "true"},
  1615  		{`{{le (index .Slice 1) .Zero}}`, "false"},
  1616  		{`{{lt (index .Slice 0) .One}}`, "true"},
  1617  		{`{{lt (index .Slice 1) .Zero}}`, "false"},
  1618  	}
  1619  
  1620  	for _, tt := range tests {
  1621  		tmpl := Must(New("tmpl").Parse(tt.text))
  1622  		var buf strings.Builder
  1623  		err := tmpl.Execute(&buf, map[string]any{
  1624  			"PlusOne": func(n int) int {
  1625  				return n + 1
  1626  			},
  1627  			"Slice": []int{0, 1, 2, 3},
  1628  			"One":   1,
  1629  			"Two":   2,
  1630  			"Nil":   nil,
  1631  			"Zero":  0,
  1632  		})
  1633  		if strings.HasPrefix(tt.out, "ERROR:") {
  1634  			e := strings.TrimSpace(strings.TrimPrefix(tt.out, "ERROR:"))
  1635  			if err == nil || !strings.Contains(err.Error(), e) {
  1636  				t.Errorf("%s: Execute: %v, want error %q", tt.text, err, e)
  1637  			}
  1638  			continue
  1639  		}
  1640  		if err != nil {
  1641  			t.Errorf("%s: Execute: %v", tt.text, err)
  1642  			continue
  1643  		}
  1644  		if buf.String() != tt.out {
  1645  			t.Errorf("%s: template output = %q, want %q", tt.text, &buf, tt.out)
  1646  		}
  1647  	}
  1648  }
  1649  
  1650  // Check that panics during calls are recovered and returned as errors.
  1651  func TestExecutePanicDuringCall(t *testing.T) {
  1652  	funcs := map[string]any{
  1653  		"doPanic": func() string {
  1654  			panic("custom panic string")
  1655  		},
  1656  	}
  1657  	tests := []struct {
  1658  		name    string
  1659  		input   string
  1660  		data    any
  1661  		wantErr string
  1662  	}{
  1663  		{
  1664  			"direct func call panics",
  1665  			"{{doPanic}}", (*T)(nil),
  1666  			`template: t:1:2: executing "t" at <doPanic>: error calling doPanic: custom panic string`,
  1667  		},
  1668  		{
  1669  			"indirect func call panics",
  1670  			"{{call doPanic}}", (*T)(nil),
  1671  			`template: t:1:7: executing "t" at <doPanic>: error calling doPanic: custom panic string`,
  1672  		},
  1673  		{
  1674  			"direct method call panics",
  1675  			"{{.GetU}}", (*T)(nil),
  1676  			`template: t:1:2: executing "t" at <.GetU>: error calling GetU: runtime error: invalid memory address or nil pointer dereference`,
  1677  		},
  1678  		{
  1679  			"indirect method call panics",
  1680  			"{{call .GetU}}", (*T)(nil),
  1681  			`template: t:1:7: executing "t" at <.GetU>: error calling GetU: runtime error: invalid memory address or nil pointer dereference`,
  1682  		},
  1683  		{
  1684  			"func field call panics",
  1685  			"{{call .PanicFunc}}", tVal,
  1686  			`template: t:1:2: executing "t" at <call .PanicFunc>: error calling call: test panic`,
  1687  		},
  1688  		{
  1689  			"method call on nil interface",
  1690  			"{{.NonEmptyInterfaceNil.Method0}}", tVal,
  1691  			`template: t:1:23: executing "t" at <.NonEmptyInterfaceNil.Method0>: nil pointer evaluating template.I.Method0`,
  1692  		},
  1693  	}
  1694  	for _, tc := range tests {
  1695  		b := new(bytes.Buffer)
  1696  		tmpl, err := New("t").Funcs(funcs).Parse(tc.input)
  1697  		if err != nil {
  1698  			t.Fatalf("parse error: %s", err)
  1699  		}
  1700  		err = tmpl.Execute(b, tc.data)
  1701  		if err == nil {
  1702  			t.Errorf("%s: expected error; got none", tc.name)
  1703  		} else if !strings.Contains(err.Error(), tc.wantErr) {
  1704  			if *debug {
  1705  				fmt.Printf("%s: test execute error: %s\n", tc.name, err)
  1706  			}
  1707  			t.Errorf("%s: expected error:\n%s\ngot:\n%s", tc.name, tc.wantErr, err)
  1708  		}
  1709  	}
  1710  }
  1711  
  1712  // Issue 31810. Check that a parenthesized first argument behaves properly.
  1713  func TestIssue31810(t *testing.T) {
  1714  	// A simple value with no arguments is fine.
  1715  	var b strings.Builder
  1716  	const text = "{{ (.)  }}"
  1717  	tmpl, err := New("").Parse(text)
  1718  	if err != nil {
  1719  		t.Error(err)
  1720  	}
  1721  	err = tmpl.Execute(&b, "result")
  1722  	if err != nil {
  1723  		t.Error(err)
  1724  	}
  1725  	if b.String() != "result" {
  1726  		t.Errorf("%s got %q, expected %q", text, b.String(), "result")
  1727  	}
  1728  
  1729  	// Even a plain function fails - need to use call.
  1730  	f := func() string { return "result" }
  1731  	b.Reset()
  1732  	err = tmpl.Execute(&b, f)
  1733  	if err == nil {
  1734  		t.Error("expected error with no call, got none")
  1735  	}
  1736  
  1737  	// Works if the function is explicitly called.
  1738  	const textCall = "{{ (call .)  }}"
  1739  	tmpl, err = New("").Parse(textCall)
  1740  	b.Reset()
  1741  	err = tmpl.Execute(&b, f)
  1742  	if err != nil {
  1743  		t.Error(err)
  1744  	}
  1745  	if b.String() != "result" {
  1746  		t.Errorf("%s got %q, expected %q", textCall, b.String(), "result")
  1747  	}
  1748  }
  1749  
  1750  // Issue 43065, range over send only channel
  1751  func TestIssue43065(t *testing.T) {
  1752  	var b bytes.Buffer
  1753  	tmp := Must(New("").Parse(`{{range .}}{{end}}`))
  1754  	ch := make(chan<- int)
  1755  	err := tmp.Execute(&b, ch)
  1756  	if err == nil {
  1757  		t.Error("expected err got nil")
  1758  	} else if !strings.Contains(err.Error(), "range over send-only channel") {
  1759  		t.Errorf("%s", err)
  1760  	}
  1761  }
  1762  
  1763  // Issue 39807: data race in html/template & text/template
  1764  func TestIssue39807(t *testing.T) {
  1765  	var wg sync.WaitGroup
  1766  
  1767  	tplFoo, err := New("foo").Parse(`{{ template "bar" . }}`)
  1768  	if err != nil {
  1769  		t.Error(err)
  1770  	}
  1771  
  1772  	tplBar, err := New("bar").Parse("bar")
  1773  	if err != nil {
  1774  		t.Error(err)
  1775  	}
  1776  
  1777  	gofuncs := 10
  1778  	numTemplates := 10
  1779  
  1780  	for i := 1; i <= gofuncs; i++ {
  1781  		wg.Add(1)
  1782  		go func() {
  1783  			defer wg.Done()
  1784  			for j := 0; j < numTemplates; j++ {
  1785  				_, err := tplFoo.AddParseTree(tplBar.Name(), tplBar.Tree)
  1786  				if err != nil {
  1787  					t.Error(err)
  1788  				}
  1789  				err = tplFoo.Execute(io.Discard, nil)
  1790  				if err != nil {
  1791  					t.Error(err)
  1792  				}
  1793  			}
  1794  		}()
  1795  	}
  1796  
  1797  	wg.Wait()
  1798  }
  1799  
  1800  // Issue 48215: embedded nil pointer causes panic.
  1801  // Fixed by adding FieldByIndexErr to the reflect package.
  1802  func TestIssue48215(t *testing.T) {
  1803  	type A struct {
  1804  		S string
  1805  	}
  1806  	type B struct {
  1807  		*A
  1808  	}
  1809  	tmpl, err := New("").Parse(`{{ .S }}`)
  1810  	if err != nil {
  1811  		t.Fatal(err)
  1812  	}
  1813  	err = tmpl.Execute(io.Discard, B{})
  1814  	// We expect an error, not a panic.
  1815  	if err == nil {
  1816  		t.Fatal("did not get error for nil embedded struct")
  1817  	}
  1818  	if !strings.Contains(err.Error(), "reflect: indirection through nil pointer to embedded struct field A") {
  1819  		t.Fatal(err)
  1820  	}
  1821  }
  1822  

View as plain text