Source file src/strings/strings_test.go

     1  // Copyright 2009 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 strings_test
     6  
     7  import (
     8  	"bytes"
     9  	"fmt"
    10  	"io"
    11  	"math/rand"
    12  	"reflect"
    13  	"strconv"
    14  	. "strings"
    15  	"testing"
    16  	"unicode"
    17  	"unicode/utf8"
    18  	"unsafe"
    19  )
    20  
    21  func eq(a, b []string) bool {
    22  	if len(a) != len(b) {
    23  		return false
    24  	}
    25  	for i := 0; i < len(a); i++ {
    26  		if a[i] != b[i] {
    27  			return false
    28  		}
    29  	}
    30  	return true
    31  }
    32  
    33  var abcd = "abcd"
    34  var faces = "☺☻☹"
    35  var commas = "1,2,3,4"
    36  var dots = "1....2....3....4"
    37  
    38  type IndexTest struct {
    39  	s   string
    40  	sep string
    41  	out int
    42  }
    43  
    44  var indexTests = []IndexTest{
    45  	{"", "", 0},
    46  	{"", "a", -1},
    47  	{"", "foo", -1},
    48  	{"fo", "foo", -1},
    49  	{"foo", "foo", 0},
    50  	{"oofofoofooo", "f", 2},
    51  	{"oofofoofooo", "foo", 4},
    52  	{"barfoobarfoo", "foo", 3},
    53  	{"foo", "", 0},
    54  	{"foo", "o", 1},
    55  	{"abcABCabc", "A", 3},
    56  	// cases with one byte strings - test special case in Index()
    57  	{"", "a", -1},
    58  	{"x", "a", -1},
    59  	{"x", "x", 0},
    60  	{"abc", "a", 0},
    61  	{"abc", "b", 1},
    62  	{"abc", "c", 2},
    63  	{"abc", "x", -1},
    64  	// test special cases in Index() for short strings
    65  	{"", "ab", -1},
    66  	{"bc", "ab", -1},
    67  	{"ab", "ab", 0},
    68  	{"xab", "ab", 1},
    69  	{"xab"[:2], "ab", -1},
    70  	{"", "abc", -1},
    71  	{"xbc", "abc", -1},
    72  	{"abc", "abc", 0},
    73  	{"xabc", "abc", 1},
    74  	{"xabc"[:3], "abc", -1},
    75  	{"xabxc", "abc", -1},
    76  	{"", "abcd", -1},
    77  	{"xbcd", "abcd", -1},
    78  	{"abcd", "abcd", 0},
    79  	{"xabcd", "abcd", 1},
    80  	{"xyabcd"[:5], "abcd", -1},
    81  	{"xbcqq", "abcqq", -1},
    82  	{"abcqq", "abcqq", 0},
    83  	{"xabcqq", "abcqq", 1},
    84  	{"xyabcqq"[:6], "abcqq", -1},
    85  	{"xabxcqq", "abcqq", -1},
    86  	{"xabcqxq", "abcqq", -1},
    87  	{"", "01234567", -1},
    88  	{"32145678", "01234567", -1},
    89  	{"01234567", "01234567", 0},
    90  	{"x01234567", "01234567", 1},
    91  	{"x0123456x01234567", "01234567", 9},
    92  	{"xx01234567"[:9], "01234567", -1},
    93  	{"", "0123456789", -1},
    94  	{"3214567844", "0123456789", -1},
    95  	{"0123456789", "0123456789", 0},
    96  	{"x0123456789", "0123456789", 1},
    97  	{"x012345678x0123456789", "0123456789", 11},
    98  	{"xyz0123456789"[:12], "0123456789", -1},
    99  	{"x01234567x89", "0123456789", -1},
   100  	{"", "0123456789012345", -1},
   101  	{"3214567889012345", "0123456789012345", -1},
   102  	{"0123456789012345", "0123456789012345", 0},
   103  	{"x0123456789012345", "0123456789012345", 1},
   104  	{"x012345678901234x0123456789012345", "0123456789012345", 17},
   105  	{"", "01234567890123456789", -1},
   106  	{"32145678890123456789", "01234567890123456789", -1},
   107  	{"01234567890123456789", "01234567890123456789", 0},
   108  	{"x01234567890123456789", "01234567890123456789", 1},
   109  	{"x0123456789012345678x01234567890123456789", "01234567890123456789", 21},
   110  	{"xyz01234567890123456789"[:22], "01234567890123456789", -1},
   111  	{"", "0123456789012345678901234567890", -1},
   112  	{"321456788901234567890123456789012345678911", "0123456789012345678901234567890", -1},
   113  	{"0123456789012345678901234567890", "0123456789012345678901234567890", 0},
   114  	{"x0123456789012345678901234567890", "0123456789012345678901234567890", 1},
   115  	{"x012345678901234567890123456789x0123456789012345678901234567890", "0123456789012345678901234567890", 32},
   116  	{"xyz0123456789012345678901234567890"[:33], "0123456789012345678901234567890", -1},
   117  	{"", "01234567890123456789012345678901", -1},
   118  	{"32145678890123456789012345678901234567890211", "01234567890123456789012345678901", -1},
   119  	{"01234567890123456789012345678901", "01234567890123456789012345678901", 0},
   120  	{"x01234567890123456789012345678901", "01234567890123456789012345678901", 1},
   121  	{"x0123456789012345678901234567890x01234567890123456789012345678901", "01234567890123456789012345678901", 33},
   122  	{"xyz01234567890123456789012345678901"[:34], "01234567890123456789012345678901", -1},
   123  	{"xxxxxx012345678901234567890123456789012345678901234567890123456789012", "012345678901234567890123456789012345678901234567890123456789012", 6},
   124  	{"", "0123456789012345678901234567890123456789", -1},
   125  	{"xx012345678901234567890123456789012345678901234567890123456789012", "0123456789012345678901234567890123456789", 2},
   126  	{"xx012345678901234567890123456789012345678901234567890123456789012"[:41], "0123456789012345678901234567890123456789", -1},
   127  	{"xx012345678901234567890123456789012345678901234567890123456789012", "0123456789012345678901234567890123456xxx", -1},
   128  	{"xx0123456789012345678901234567890123456789012345678901234567890120123456789012345678901234567890123456xxx", "0123456789012345678901234567890123456xxx", 65},
   129  	// test fallback to Rabin-Karp.
   130  	{"oxoxoxoxoxoxoxoxoxoxoxoy", "oy", 22},
   131  	{"oxoxoxoxoxoxoxoxoxoxoxox", "oy", -1},
   132  }
   133  
   134  var lastIndexTests = []IndexTest{
   135  	{"", "", 0},
   136  	{"", "a", -1},
   137  	{"", "foo", -1},
   138  	{"fo", "foo", -1},
   139  	{"foo", "foo", 0},
   140  	{"foo", "f", 0},
   141  	{"oofofoofooo", "f", 7},
   142  	{"oofofoofooo", "foo", 7},
   143  	{"barfoobarfoo", "foo", 9},
   144  	{"foo", "", 3},
   145  	{"foo", "o", 2},
   146  	{"abcABCabc", "A", 3},
   147  	{"abcABCabc", "a", 6},
   148  }
   149  
   150  var indexAnyTests = []IndexTest{
   151  	{"", "", -1},
   152  	{"", "a", -1},
   153  	{"", "abc", -1},
   154  	{"a", "", -1},
   155  	{"a", "a", 0},
   156  	{"\x80", "\xffb", 0},
   157  	{"aaa", "a", 0},
   158  	{"abc", "xyz", -1},
   159  	{"abc", "xcz", 2},
   160  	{"ab☺c", "x☺yz", 2},
   161  	{"a☺b☻c☹d", "cx", len("a☺b☻")},
   162  	{"a☺b☻c☹d", "uvw☻xyz", len("a☺b")},
   163  	{"aRegExp*", ".(|)*+?^$[]", 7},
   164  	{dots + dots + dots, " ", -1},
   165  	{"012abcba210", "\xffb", 4},
   166  	{"012\x80bcb\x80210", "\xffb", 3},
   167  	{"0123456\xcf\x80abc", "\xcfb\x80", 10},
   168  }
   169  
   170  var lastIndexAnyTests = []IndexTest{
   171  	{"", "", -1},
   172  	{"", "a", -1},
   173  	{"", "abc", -1},
   174  	{"a", "", -1},
   175  	{"a", "a", 0},
   176  	{"\x80", "\xffb", 0},
   177  	{"aaa", "a", 2},
   178  	{"abc", "xyz", -1},
   179  	{"abc", "ab", 1},
   180  	{"ab☺c", "x☺yz", 2},
   181  	{"a☺b☻c☹d", "cx", len("a☺b☻")},
   182  	{"a☺b☻c☹d", "uvw☻xyz", len("a☺b")},
   183  	{"a.RegExp*", ".(|)*+?^$[]", 8},
   184  	{dots + dots + dots, " ", -1},
   185  	{"012abcba210", "\xffb", 6},
   186  	{"012\x80bcb\x80210", "\xffb", 7},
   187  	{"0123456\xcf\x80abc", "\xcfb\x80", 10},
   188  }
   189  
   190  // Execute f on each test case.  funcName should be the name of f; it's used
   191  // in failure reports.
   192  func runIndexTests(t *testing.T, f func(s, sep string) int, funcName string, testCases []IndexTest) {
   193  	for _, test := range testCases {
   194  		actual := f(test.s, test.sep)
   195  		if actual != test.out {
   196  			t.Errorf("%s(%q,%q) = %v; want %v", funcName, test.s, test.sep, actual, test.out)
   197  		}
   198  	}
   199  }
   200  
   201  func TestIndex(t *testing.T)     { runIndexTests(t, Index, "Index", indexTests) }
   202  func TestLastIndex(t *testing.T) { runIndexTests(t, LastIndex, "LastIndex", lastIndexTests) }
   203  func TestIndexAny(t *testing.T)  { runIndexTests(t, IndexAny, "IndexAny", indexAnyTests) }
   204  func TestLastIndexAny(t *testing.T) {
   205  	runIndexTests(t, LastIndexAny, "LastIndexAny", lastIndexAnyTests)
   206  }
   207  
   208  func TestIndexByte(t *testing.T) {
   209  	for _, tt := range indexTests {
   210  		if len(tt.sep) != 1 {
   211  			continue
   212  		}
   213  		pos := IndexByte(tt.s, tt.sep[0])
   214  		if pos != tt.out {
   215  			t.Errorf(`IndexByte(%q, %q) = %v; want %v`, tt.s, tt.sep[0], pos, tt.out)
   216  		}
   217  	}
   218  }
   219  
   220  func TestLastIndexByte(t *testing.T) {
   221  	testCases := []IndexTest{
   222  		{"", "q", -1},
   223  		{"abcdef", "q", -1},
   224  		{"abcdefabcdef", "a", len("abcdef")},      // something in the middle
   225  		{"abcdefabcdef", "f", len("abcdefabcde")}, // last byte
   226  		{"zabcdefabcdef", "z", 0},                 // first byte
   227  		{"a☺b☻c☹d", "b", len("a☺")},               // non-ascii
   228  	}
   229  	for _, test := range testCases {
   230  		actual := LastIndexByte(test.s, test.sep[0])
   231  		if actual != test.out {
   232  			t.Errorf("LastIndexByte(%q,%c) = %v; want %v", test.s, test.sep[0], actual, test.out)
   233  		}
   234  	}
   235  }
   236  
   237  func simpleIndex(s, sep string) int {
   238  	n := len(sep)
   239  	for i := n; i <= len(s); i++ {
   240  		if s[i-n:i] == sep {
   241  			return i - n
   242  		}
   243  	}
   244  	return -1
   245  }
   246  
   247  func TestIndexRandom(t *testing.T) {
   248  	const chars = "abcdefghijklmnopqrstuvwxyz0123456789"
   249  	for times := 0; times < 10; times++ {
   250  		for strLen := 5 + rand.Intn(5); strLen < 140; strLen += 10 { // Arbitrary
   251  			s1 := make([]byte, strLen)
   252  			for i := range s1 {
   253  				s1[i] = chars[rand.Intn(len(chars))]
   254  			}
   255  			s := string(s1)
   256  			for i := 0; i < 50; i++ {
   257  				begin := rand.Intn(len(s) + 1)
   258  				end := begin + rand.Intn(len(s)+1-begin)
   259  				sep := s[begin:end]
   260  				if i%4 == 0 {
   261  					pos := rand.Intn(len(sep) + 1)
   262  					sep = sep[:pos] + "A" + sep[pos:]
   263  				}
   264  				want := simpleIndex(s, sep)
   265  				res := Index(s, sep)
   266  				if res != want {
   267  					t.Errorf("Index(%s,%s) = %d; want %d", s, sep, res, want)
   268  				}
   269  			}
   270  		}
   271  	}
   272  }
   273  
   274  func TestIndexRune(t *testing.T) {
   275  	tests := []struct {
   276  		in   string
   277  		rune rune
   278  		want int
   279  	}{
   280  		{"", 'a', -1},
   281  		{"", '☺', -1},
   282  		{"foo", '☹', -1},
   283  		{"foo", 'o', 1},
   284  		{"foo☺bar", '☺', 3},
   285  		{"foo☺☻☹bar", '☹', 9},
   286  		{"a A x", 'A', 2},
   287  		{"some_text=some_value", '=', 9},
   288  		{"☺a", 'a', 3},
   289  		{"a☻☺b", '☺', 4},
   290  
   291  		// RuneError should match any invalid UTF-8 byte sequence.
   292  		{"�", '�', 0},
   293  		{"\xff", '�', 0},
   294  		{"☻x�", '�', len("☻x")},
   295  		{"☻x\xe2\x98", '�', len("☻x")},
   296  		{"☻x\xe2\x98�", '�', len("☻x")},
   297  		{"☻x\xe2\x98x", '�', len("☻x")},
   298  
   299  		// Invalid rune values should never match.
   300  		{"a☺b☻c☹d\xe2\x98�\xff�\xed\xa0\x80", -1, -1},
   301  		{"a☺b☻c☹d\xe2\x98�\xff�\xed\xa0\x80", 0xD800, -1}, // Surrogate pair
   302  		{"a☺b☻c☹d\xe2\x98�\xff�\xed\xa0\x80", utf8.MaxRune + 1, -1},
   303  	}
   304  	for _, tt := range tests {
   305  		if got := IndexRune(tt.in, tt.rune); got != tt.want {
   306  			t.Errorf("IndexRune(%q, %d) = %v; want %v", tt.in, tt.rune, got, tt.want)
   307  		}
   308  	}
   309  
   310  	haystack := "test世界"
   311  	allocs := testing.AllocsPerRun(1000, func() {
   312  		if i := IndexRune(haystack, 's'); i != 2 {
   313  			t.Fatalf("'s' at %d; want 2", i)
   314  		}
   315  		if i := IndexRune(haystack, '世'); i != 4 {
   316  			t.Fatalf("'世' at %d; want 4", i)
   317  		}
   318  	})
   319  	if allocs != 0 && testing.CoverMode() == "" {
   320  		t.Errorf("expected no allocations, got %f", allocs)
   321  	}
   322  }
   323  
   324  const benchmarkString = "some_text=some☺value"
   325  
   326  func BenchmarkIndexRune(b *testing.B) {
   327  	if got := IndexRune(benchmarkString, '☺'); got != 14 {
   328  		b.Fatalf("wrong index: expected 14, got=%d", got)
   329  	}
   330  	for i := 0; i < b.N; i++ {
   331  		IndexRune(benchmarkString, '☺')
   332  	}
   333  }
   334  
   335  var benchmarkLongString = Repeat(" ", 100) + benchmarkString
   336  
   337  func BenchmarkIndexRuneLongString(b *testing.B) {
   338  	if got := IndexRune(benchmarkLongString, '☺'); got != 114 {
   339  		b.Fatalf("wrong index: expected 114, got=%d", got)
   340  	}
   341  	for i := 0; i < b.N; i++ {
   342  		IndexRune(benchmarkLongString, '☺')
   343  	}
   344  }
   345  
   346  func BenchmarkIndexRuneFastPath(b *testing.B) {
   347  	if got := IndexRune(benchmarkString, 'v'); got != 17 {
   348  		b.Fatalf("wrong index: expected 17, got=%d", got)
   349  	}
   350  	for i := 0; i < b.N; i++ {
   351  		IndexRune(benchmarkString, 'v')
   352  	}
   353  }
   354  
   355  func BenchmarkIndex(b *testing.B) {
   356  	if got := Index(benchmarkString, "v"); got != 17 {
   357  		b.Fatalf("wrong index: expected 17, got=%d", got)
   358  	}
   359  	for i := 0; i < b.N; i++ {
   360  		Index(benchmarkString, "v")
   361  	}
   362  }
   363  
   364  func BenchmarkLastIndex(b *testing.B) {
   365  	if got := Index(benchmarkString, "v"); got != 17 {
   366  		b.Fatalf("wrong index: expected 17, got=%d", got)
   367  	}
   368  	for i := 0; i < b.N; i++ {
   369  		LastIndex(benchmarkString, "v")
   370  	}
   371  }
   372  
   373  func BenchmarkIndexByte(b *testing.B) {
   374  	if got := IndexByte(benchmarkString, 'v'); got != 17 {
   375  		b.Fatalf("wrong index: expected 17, got=%d", got)
   376  	}
   377  	for i := 0; i < b.N; i++ {
   378  		IndexByte(benchmarkString, 'v')
   379  	}
   380  }
   381  
   382  type SplitTest struct {
   383  	s   string
   384  	sep string
   385  	n   int
   386  	a   []string
   387  }
   388  
   389  var splittests = []SplitTest{
   390  	{"", "", -1, []string{}},
   391  	{abcd, "", 2, []string{"a", "bcd"}},
   392  	{abcd, "", 4, []string{"a", "b", "c", "d"}},
   393  	{abcd, "", -1, []string{"a", "b", "c", "d"}},
   394  	{faces, "", -1, []string{"☺", "☻", "☹"}},
   395  	{faces, "", 3, []string{"☺", "☻", "☹"}},
   396  	{faces, "", 17, []string{"☺", "☻", "☹"}},
   397  	{"☺�☹", "", -1, []string{"☺", "�", "☹"}},
   398  	{abcd, "a", 0, nil},
   399  	{abcd, "a", -1, []string{"", "bcd"}},
   400  	{abcd, "z", -1, []string{"abcd"}},
   401  	{commas, ",", -1, []string{"1", "2", "3", "4"}},
   402  	{dots, "...", -1, []string{"1", ".2", ".3", ".4"}},
   403  	{faces, "☹", -1, []string{"☺☻", ""}},
   404  	{faces, "~", -1, []string{faces}},
   405  	{"1 2 3 4", " ", 3, []string{"1", "2", "3 4"}},
   406  	{"1 2", " ", 3, []string{"1", "2"}},
   407  }
   408  
   409  func TestSplit(t *testing.T) {
   410  	for _, tt := range splittests {
   411  		a := SplitN(tt.s, tt.sep, tt.n)
   412  		if !eq(a, tt.a) {
   413  			t.Errorf("Split(%q, %q, %d) = %v; want %v", tt.s, tt.sep, tt.n, a, tt.a)
   414  			continue
   415  		}
   416  		if tt.n == 0 {
   417  			continue
   418  		}
   419  		s := Join(a, tt.sep)
   420  		if s != tt.s {
   421  			t.Errorf("Join(Split(%q, %q, %d), %q) = %q", tt.s, tt.sep, tt.n, tt.sep, s)
   422  		}
   423  		if tt.n < 0 {
   424  			b := Split(tt.s, tt.sep)
   425  			if !reflect.DeepEqual(a, b) {
   426  				t.Errorf("Split disagrees with SplitN(%q, %q, %d) = %v; want %v", tt.s, tt.sep, tt.n, b, a)
   427  			}
   428  		}
   429  	}
   430  }
   431  
   432  var splitaftertests = []SplitTest{
   433  	{abcd, "a", -1, []string{"a", "bcd"}},
   434  	{abcd, "z", -1, []string{"abcd"}},
   435  	{abcd, "", -1, []string{"a", "b", "c", "d"}},
   436  	{commas, ",", -1, []string{"1,", "2,", "3,", "4"}},
   437  	{dots, "...", -1, []string{"1...", ".2...", ".3...", ".4"}},
   438  	{faces, "☹", -1, []string{"☺☻☹", ""}},
   439  	{faces, "~", -1, []string{faces}},
   440  	{faces, "", -1, []string{"☺", "☻", "☹"}},
   441  	{"1 2 3 4", " ", 3, []string{"1 ", "2 ", "3 4"}},
   442  	{"1 2 3", " ", 3, []string{"1 ", "2 ", "3"}},
   443  	{"1 2", " ", 3, []string{"1 ", "2"}},
   444  	{"123", "", 2, []string{"1", "23"}},
   445  	{"123", "", 17, []string{"1", "2", "3"}},
   446  }
   447  
   448  func TestSplitAfter(t *testing.T) {
   449  	for _, tt := range splitaftertests {
   450  		a := SplitAfterN(tt.s, tt.sep, tt.n)
   451  		if !eq(a, tt.a) {
   452  			t.Errorf(`Split(%q, %q, %d) = %v; want %v`, tt.s, tt.sep, tt.n, a, tt.a)
   453  			continue
   454  		}
   455  		s := Join(a, "")
   456  		if s != tt.s {
   457  			t.Errorf(`Join(Split(%q, %q, %d), %q) = %q`, tt.s, tt.sep, tt.n, tt.sep, s)
   458  		}
   459  		if tt.n < 0 {
   460  			b := SplitAfter(tt.s, tt.sep)
   461  			if !reflect.DeepEqual(a, b) {
   462  				t.Errorf("SplitAfter disagrees with SplitAfterN(%q, %q, %d) = %v; want %v", tt.s, tt.sep, tt.n, b, a)
   463  			}
   464  		}
   465  	}
   466  }
   467  
   468  type FieldsTest struct {
   469  	s string
   470  	a []string
   471  }
   472  
   473  var fieldstests = []FieldsTest{
   474  	{"", []string{}},
   475  	{" ", []string{}},
   476  	{" \t ", []string{}},
   477  	{"\u2000", []string{}},
   478  	{"  abc  ", []string{"abc"}},
   479  	{"1 2 3 4", []string{"1", "2", "3", "4"}},
   480  	{"1  2  3  4", []string{"1", "2", "3", "4"}},
   481  	{"1\t\t2\t\t3\t4", []string{"1", "2", "3", "4"}},
   482  	{"1\u20002\u20013\u20024", []string{"1", "2", "3", "4"}},
   483  	{"\u2000\u2001\u2002", []string{}},
   484  	{"\n™\t™\n", []string{"™", "™"}},
   485  	{"\n\u20001™2\u2000 \u2001 ™", []string{"1™2", "™"}},
   486  	{"\n1\uFFFD \uFFFD2\u20003\uFFFD4", []string{"1\uFFFD", "\uFFFD2", "3\uFFFD4"}},
   487  	{"1\xFF\u2000\xFF2\xFF \xFF", []string{"1\xFF", "\xFF2\xFF", "\xFF"}},
   488  	{faces, []string{faces}},
   489  }
   490  
   491  func TestFields(t *testing.T) {
   492  	for _, tt := range fieldstests {
   493  		a := Fields(tt.s)
   494  		if !eq(a, tt.a) {
   495  			t.Errorf("Fields(%q) = %v; want %v", tt.s, a, tt.a)
   496  			continue
   497  		}
   498  	}
   499  }
   500  
   501  var FieldsFuncTests = []FieldsTest{
   502  	{"", []string{}},
   503  	{"XX", []string{}},
   504  	{"XXhiXXX", []string{"hi"}},
   505  	{"aXXbXXXcX", []string{"a", "b", "c"}},
   506  }
   507  
   508  func TestFieldsFunc(t *testing.T) {
   509  	for _, tt := range fieldstests {
   510  		a := FieldsFunc(tt.s, unicode.IsSpace)
   511  		if !eq(a, tt.a) {
   512  			t.Errorf("FieldsFunc(%q, unicode.IsSpace) = %v; want %v", tt.s, a, tt.a)
   513  			continue
   514  		}
   515  	}
   516  	pred := func(c rune) bool { return c == 'X' }
   517  	for _, tt := range FieldsFuncTests {
   518  		a := FieldsFunc(tt.s, pred)
   519  		if !eq(a, tt.a) {
   520  			t.Errorf("FieldsFunc(%q) = %v, want %v", tt.s, a, tt.a)
   521  		}
   522  	}
   523  }
   524  
   525  // Test case for any function which accepts and returns a single string.
   526  type StringTest struct {
   527  	in, out string
   528  }
   529  
   530  // Execute f on each test case.  funcName should be the name of f; it's used
   531  // in failure reports.
   532  func runStringTests(t *testing.T, f func(string) string, funcName string, testCases []StringTest) {
   533  	for _, tc := range testCases {
   534  		actual := f(tc.in)
   535  		if actual != tc.out {
   536  			t.Errorf("%s(%q) = %q; want %q", funcName, tc.in, actual, tc.out)
   537  		}
   538  	}
   539  }
   540  
   541  var upperTests = []StringTest{
   542  	{"", ""},
   543  	{"ONLYUPPER", "ONLYUPPER"},
   544  	{"abc", "ABC"},
   545  	{"AbC123", "ABC123"},
   546  	{"azAZ09_", "AZAZ09_"},
   547  	{"longStrinGwitHmixofsmaLLandcAps", "LONGSTRINGWITHMIXOFSMALLANDCAPS"},
   548  	{"long\u0250string\u0250with\u0250nonascii\u2C6Fchars", "LONG\u2C6FSTRING\u2C6FWITH\u2C6FNONASCII\u2C6FCHARS"},
   549  	{"\u0250\u0250\u0250\u0250\u0250", "\u2C6F\u2C6F\u2C6F\u2C6F\u2C6F"}, // grows one byte per char
   550  	{"a\u0080\U0010FFFF", "A\u0080\U0010FFFF"},                           // test utf8.RuneSelf and utf8.MaxRune
   551  }
   552  
   553  var lowerTests = []StringTest{
   554  	{"", ""},
   555  	{"abc", "abc"},
   556  	{"AbC123", "abc123"},
   557  	{"azAZ09_", "azaz09_"},
   558  	{"longStrinGwitHmixofsmaLLandcAps", "longstringwithmixofsmallandcaps"},
   559  	{"LONG\u2C6FSTRING\u2C6FWITH\u2C6FNONASCII\u2C6FCHARS", "long\u0250string\u0250with\u0250nonascii\u0250chars"},
   560  	{"\u2C6D\u2C6D\u2C6D\u2C6D\u2C6D", "\u0251\u0251\u0251\u0251\u0251"}, // shrinks one byte per char
   561  	{"A\u0080\U0010FFFF", "a\u0080\U0010FFFF"},                           // test utf8.RuneSelf and utf8.MaxRune
   562  }
   563  
   564  const space = "\t\v\r\f\n\u0085\u00a0\u2000\u3000"
   565  
   566  var trimSpaceTests = []StringTest{
   567  	{"", ""},
   568  	{"abc", "abc"},
   569  	{space + "abc" + space, "abc"},
   570  	{" ", ""},
   571  	{" \t\r\n \t\t\r\r\n\n ", ""},
   572  	{" \t\r\n x\t\t\r\r\n\n ", "x"},
   573  	{" \u2000\t\r\n x\t\t\r\r\ny\n \u3000", "x\t\t\r\r\ny"},
   574  	{"1 \t\r\n2", "1 \t\r\n2"},
   575  	{" x\x80", "x\x80"},
   576  	{" x\xc0", "x\xc0"},
   577  	{"x \xc0\xc0 ", "x \xc0\xc0"},
   578  	{"x \xc0", "x \xc0"},
   579  	{"x \xc0 ", "x \xc0"},
   580  	{"x \xc0\xc0 ", "x \xc0\xc0"},
   581  	{"x ☺\xc0\xc0 ", "x ☺\xc0\xc0"},
   582  	{"x ☺ ", "x ☺"},
   583  }
   584  
   585  func tenRunes(ch rune) string {
   586  	r := make([]rune, 10)
   587  	for i := range r {
   588  		r[i] = ch
   589  	}
   590  	return string(r)
   591  }
   592  
   593  // User-defined self-inverse mapping function
   594  func rot13(r rune) rune {
   595  	step := rune(13)
   596  	if r >= 'a' && r <= 'z' {
   597  		return ((r - 'a' + step) % 26) + 'a'
   598  	}
   599  	if r >= 'A' && r <= 'Z' {
   600  		return ((r - 'A' + step) % 26) + 'A'
   601  	}
   602  	return r
   603  }
   604  
   605  func TestMap(t *testing.T) {
   606  	// Run a couple of awful growth/shrinkage tests
   607  	a := tenRunes('a')
   608  	// 1.  Grow. This triggers two reallocations in Map.
   609  	maxRune := func(rune) rune { return unicode.MaxRune }
   610  	m := Map(maxRune, a)
   611  	expect := tenRunes(unicode.MaxRune)
   612  	if m != expect {
   613  		t.Errorf("growing: expected %q got %q", expect, m)
   614  	}
   615  
   616  	// 2. Shrink
   617  	minRune := func(rune) rune { return 'a' }
   618  	m = Map(minRune, tenRunes(unicode.MaxRune))
   619  	expect = a
   620  	if m != expect {
   621  		t.Errorf("shrinking: expected %q got %q", expect, m)
   622  	}
   623  
   624  	// 3. Rot13
   625  	m = Map(rot13, "a to zed")
   626  	expect = "n gb mrq"
   627  	if m != expect {
   628  		t.Errorf("rot13: expected %q got %q", expect, m)
   629  	}
   630  
   631  	// 4. Rot13^2
   632  	m = Map(rot13, Map(rot13, "a to zed"))
   633  	expect = "a to zed"
   634  	if m != expect {
   635  		t.Errorf("rot13: expected %q got %q", expect, m)
   636  	}
   637  
   638  	// 5. Drop
   639  	dropNotLatin := func(r rune) rune {
   640  		if unicode.Is(unicode.Latin, r) {
   641  			return r
   642  		}
   643  		return -1
   644  	}
   645  	m = Map(dropNotLatin, "Hello, 세계")
   646  	expect = "Hello"
   647  	if m != expect {
   648  		t.Errorf("drop: expected %q got %q", expect, m)
   649  	}
   650  
   651  	// 6. Identity
   652  	identity := func(r rune) rune {
   653  		return r
   654  	}
   655  	orig := "Input string that we expect not to be copied."
   656  	m = Map(identity, orig)
   657  	if (*reflect.StringHeader)(unsafe.Pointer(&orig)).Data !=
   658  		(*reflect.StringHeader)(unsafe.Pointer(&m)).Data {
   659  		t.Error("unexpected copy during identity map")
   660  	}
   661  
   662  	// 7. Handle invalid UTF-8 sequence
   663  	replaceNotLatin := func(r rune) rune {
   664  		if unicode.Is(unicode.Latin, r) {
   665  			return r
   666  		}
   667  		return utf8.RuneError
   668  	}
   669  	m = Map(replaceNotLatin, "Hello\255World")
   670  	expect = "Hello\uFFFDWorld"
   671  	if m != expect {
   672  		t.Errorf("replace invalid sequence: expected %q got %q", expect, m)
   673  	}
   674  
   675  	// 8. Check utf8.RuneSelf and utf8.MaxRune encoding
   676  	encode := func(r rune) rune {
   677  		switch r {
   678  		case utf8.RuneSelf:
   679  			return unicode.MaxRune
   680  		case unicode.MaxRune:
   681  			return utf8.RuneSelf
   682  		}
   683  		return r
   684  	}
   685  	s := string(rune(utf8.RuneSelf)) + string(utf8.MaxRune)
   686  	r := string(utf8.MaxRune) + string(rune(utf8.RuneSelf)) // reverse of s
   687  	m = Map(encode, s)
   688  	if m != r {
   689  		t.Errorf("encoding not handled correctly: expected %q got %q", r, m)
   690  	}
   691  	m = Map(encode, r)
   692  	if m != s {
   693  		t.Errorf("encoding not handled correctly: expected %q got %q", s, m)
   694  	}
   695  
   696  	// 9. Check mapping occurs in the front, middle and back
   697  	trimSpaces := func(r rune) rune {
   698  		if unicode.IsSpace(r) {
   699  			return -1
   700  		}
   701  		return r
   702  	}
   703  	m = Map(trimSpaces, "   abc    123   ")
   704  	expect = "abc123"
   705  	if m != expect {
   706  		t.Errorf("trimSpaces: expected %q got %q", expect, m)
   707  	}
   708  }
   709  
   710  func TestToUpper(t *testing.T) { runStringTests(t, ToUpper, "ToUpper", upperTests) }
   711  
   712  func TestToLower(t *testing.T) { runStringTests(t, ToLower, "ToLower", lowerTests) }
   713  
   714  var toValidUTF8Tests = []struct {
   715  	in   string
   716  	repl string
   717  	out  string
   718  }{
   719  	{"", "\uFFFD", ""},
   720  	{"abc", "\uFFFD", "abc"},
   721  	{"\uFDDD", "\uFFFD", "\uFDDD"},
   722  	{"a\xffb", "\uFFFD", "a\uFFFDb"},
   723  	{"a\xffb\uFFFD", "X", "aXb\uFFFD"},
   724  	{"a☺\xffb☺\xC0\xAFc☺\xff", "", "a☺b☺c☺"},
   725  	{"a☺\xffb☺\xC0\xAFc☺\xff", "日本語", "a☺日本語b☺日本語c☺日本語"},
   726  	{"\xC0\xAF", "\uFFFD", "\uFFFD"},
   727  	{"\xE0\x80\xAF", "\uFFFD", "\uFFFD"},
   728  	{"\xed\xa0\x80", "abc", "abc"},
   729  	{"\xed\xbf\xbf", "\uFFFD", "\uFFFD"},
   730  	{"\xF0\x80\x80\xaf", "☺", "☺"},
   731  	{"\xF8\x80\x80\x80\xAF", "\uFFFD", "\uFFFD"},
   732  	{"\xFC\x80\x80\x80\x80\xAF", "\uFFFD", "\uFFFD"},
   733  }
   734  
   735  func TestToValidUTF8(t *testing.T) {
   736  	for _, tc := range toValidUTF8Tests {
   737  		got := ToValidUTF8(tc.in, tc.repl)
   738  		if got != tc.out {
   739  			t.Errorf("ToValidUTF8(%q, %q) = %q; want %q", tc.in, tc.repl, got, tc.out)
   740  		}
   741  	}
   742  }
   743  
   744  func BenchmarkToUpper(b *testing.B) {
   745  	for _, tc := range upperTests {
   746  		b.Run(tc.in, func(b *testing.B) {
   747  			for i := 0; i < b.N; i++ {
   748  				actual := ToUpper(tc.in)
   749  				if actual != tc.out {
   750  					b.Errorf("ToUpper(%q) = %q; want %q", tc.in, actual, tc.out)
   751  				}
   752  			}
   753  		})
   754  	}
   755  }
   756  
   757  func BenchmarkToLower(b *testing.B) {
   758  	for _, tc := range lowerTests {
   759  		b.Run(tc.in, func(b *testing.B) {
   760  			for i := 0; i < b.N; i++ {
   761  				actual := ToLower(tc.in)
   762  				if actual != tc.out {
   763  					b.Errorf("ToLower(%q) = %q; want %q", tc.in, actual, tc.out)
   764  				}
   765  			}
   766  		})
   767  	}
   768  }
   769  
   770  func BenchmarkMapNoChanges(b *testing.B) {
   771  	identity := func(r rune) rune {
   772  		return r
   773  	}
   774  	for i := 0; i < b.N; i++ {
   775  		Map(identity, "Some string that won't be modified.")
   776  	}
   777  }
   778  
   779  func TestSpecialCase(t *testing.T) {
   780  	lower := "abcçdefgğhıijklmnoöprsştuüvyz"
   781  	upper := "ABCÇDEFGĞHIİJKLMNOÖPRSŞTUÜVYZ"
   782  	u := ToUpperSpecial(unicode.TurkishCase, upper)
   783  	if u != upper {
   784  		t.Errorf("Upper(upper) is %s not %s", u, upper)
   785  	}
   786  	u = ToUpperSpecial(unicode.TurkishCase, lower)
   787  	if u != upper {
   788  		t.Errorf("Upper(lower) is %s not %s", u, upper)
   789  	}
   790  	l := ToLowerSpecial(unicode.TurkishCase, lower)
   791  	if l != lower {
   792  		t.Errorf("Lower(lower) is %s not %s", l, lower)
   793  	}
   794  	l = ToLowerSpecial(unicode.TurkishCase, upper)
   795  	if l != lower {
   796  		t.Errorf("Lower(upper) is %s not %s", l, lower)
   797  	}
   798  }
   799  
   800  func TestTrimSpace(t *testing.T) { runStringTests(t, TrimSpace, "TrimSpace", trimSpaceTests) }
   801  
   802  var trimTests = []struct {
   803  	f            string
   804  	in, arg, out string
   805  }{
   806  	{"Trim", "abba", "a", "bb"},
   807  	{"Trim", "abba", "ab", ""},
   808  	{"TrimLeft", "abba", "ab", ""},
   809  	{"TrimRight", "abba", "ab", ""},
   810  	{"TrimLeft", "abba", "a", "bba"},
   811  	{"TrimLeft", "abba", "b", "abba"},
   812  	{"TrimRight", "abba", "a", "abb"},
   813  	{"TrimRight", "abba", "b", "abba"},
   814  	{"Trim", "<tag>", "<>", "tag"},
   815  	{"Trim", "* listitem", " *", "listitem"},
   816  	{"Trim", `"quote"`, `"`, "quote"},
   817  	{"Trim", "\u2C6F\u2C6F\u0250\u0250\u2C6F\u2C6F", "\u2C6F", "\u0250\u0250"},
   818  	{"Trim", "\x80test\xff", "\xff", "test"},
   819  	{"Trim", " Ġ ", " ", "Ġ"},
   820  	{"Trim", " Ġİ0", "0 ", "Ġİ"},
   821  	//empty string tests
   822  	{"Trim", "abba", "", "abba"},
   823  	{"Trim", "", "123", ""},
   824  	{"Trim", "", "", ""},
   825  	{"TrimLeft", "abba", "", "abba"},
   826  	{"TrimLeft", "", "123", ""},
   827  	{"TrimLeft", "", "", ""},
   828  	{"TrimRight", "abba", "", "abba"},
   829  	{"TrimRight", "", "123", ""},
   830  	{"TrimRight", "", "", ""},
   831  	{"TrimRight", "☺\xc0", "☺", "☺\xc0"},
   832  	{"TrimPrefix", "aabb", "a", "abb"},
   833  	{"TrimPrefix", "aabb", "b", "aabb"},
   834  	{"TrimSuffix", "aabb", "a", "aabb"},
   835  	{"TrimSuffix", "aabb", "b", "aab"},
   836  }
   837  
   838  func TestTrim(t *testing.T) {
   839  	for _, tc := range trimTests {
   840  		name := tc.f
   841  		var f func(string, string) string
   842  		switch name {
   843  		case "Trim":
   844  			f = Trim
   845  		case "TrimLeft":
   846  			f = TrimLeft
   847  		case "TrimRight":
   848  			f = TrimRight
   849  		case "TrimPrefix":
   850  			f = TrimPrefix
   851  		case "TrimSuffix":
   852  			f = TrimSuffix
   853  		default:
   854  			t.Errorf("Undefined trim function %s", name)
   855  		}
   856  		actual := f(tc.in, tc.arg)
   857  		if actual != tc.out {
   858  			t.Errorf("%s(%q, %q) = %q; want %q", name, tc.in, tc.arg, actual, tc.out)
   859  		}
   860  	}
   861  }
   862  
   863  func BenchmarkTrim(b *testing.B) {
   864  	b.ReportAllocs()
   865  
   866  	for i := 0; i < b.N; i++ {
   867  		for _, tc := range trimTests {
   868  			name := tc.f
   869  			var f func(string, string) string
   870  			switch name {
   871  			case "Trim":
   872  				f = Trim
   873  			case "TrimLeft":
   874  				f = TrimLeft
   875  			case "TrimRight":
   876  				f = TrimRight
   877  			case "TrimPrefix":
   878  				f = TrimPrefix
   879  			case "TrimSuffix":
   880  				f = TrimSuffix
   881  			default:
   882  				b.Errorf("Undefined trim function %s", name)
   883  			}
   884  			actual := f(tc.in, tc.arg)
   885  			if actual != tc.out {
   886  				b.Errorf("%s(%q, %q) = %q; want %q", name, tc.in, tc.arg, actual, tc.out)
   887  			}
   888  		}
   889  	}
   890  }
   891  
   892  func BenchmarkToValidUTF8(b *testing.B) {
   893  	tests := []struct {
   894  		name  string
   895  		input string
   896  	}{
   897  		{"Valid", "typical"},
   898  		{"InvalidASCII", "foo\xffbar"},
   899  		{"InvalidNonASCII", "日本語\xff日本語"},
   900  	}
   901  	replacement := "\uFFFD"
   902  	b.ResetTimer()
   903  	for _, test := range tests {
   904  		b.Run(test.name, func(b *testing.B) {
   905  			for i := 0; i < b.N; i++ {
   906  				ToValidUTF8(test.input, replacement)
   907  			}
   908  		})
   909  	}
   910  }
   911  
   912  type predicate struct {
   913  	f    func(rune) bool
   914  	name string
   915  }
   916  
   917  var isSpace = predicate{unicode.IsSpace, "IsSpace"}
   918  var isDigit = predicate{unicode.IsDigit, "IsDigit"}
   919  var isUpper = predicate{unicode.IsUpper, "IsUpper"}
   920  var isValidRune = predicate{
   921  	func(r rune) bool {
   922  		return r != utf8.RuneError
   923  	},
   924  	"IsValidRune",
   925  }
   926  
   927  func not(p predicate) predicate {
   928  	return predicate{
   929  		func(r rune) bool {
   930  			return !p.f(r)
   931  		},
   932  		"not " + p.name,
   933  	}
   934  }
   935  
   936  var trimFuncTests = []struct {
   937  	f        predicate
   938  	in       string
   939  	trimOut  string
   940  	leftOut  string
   941  	rightOut string
   942  }{
   943  	{isSpace, space + " hello " + space,
   944  		"hello",
   945  		"hello " + space,
   946  		space + " hello"},
   947  	{isDigit, "\u0e50\u0e5212hello34\u0e50\u0e51",
   948  		"hello",
   949  		"hello34\u0e50\u0e51",
   950  		"\u0e50\u0e5212hello"},
   951  	{isUpper, "\u2C6F\u2C6F\u2C6F\u2C6FABCDhelloEF\u2C6F\u2C6FGH\u2C6F\u2C6F",
   952  		"hello",
   953  		"helloEF\u2C6F\u2C6FGH\u2C6F\u2C6F",
   954  		"\u2C6F\u2C6F\u2C6F\u2C6FABCDhello"},
   955  	{not(isSpace), "hello" + space + "hello",
   956  		space,
   957  		space + "hello",
   958  		"hello" + space},
   959  	{not(isDigit), "hello\u0e50\u0e521234\u0e50\u0e51helo",
   960  		"\u0e50\u0e521234\u0e50\u0e51",
   961  		"\u0e50\u0e521234\u0e50\u0e51helo",
   962  		"hello\u0e50\u0e521234\u0e50\u0e51"},
   963  	{isValidRune, "ab\xc0a\xc0cd",
   964  		"\xc0a\xc0",
   965  		"\xc0a\xc0cd",
   966  		"ab\xc0a\xc0"},
   967  	{not(isValidRune), "\xc0a\xc0",
   968  		"a",
   969  		"a\xc0",
   970  		"\xc0a"},
   971  	{isSpace, "",
   972  		"",
   973  		"",
   974  		""},
   975  	{isSpace, " ",
   976  		"",
   977  		"",
   978  		""},
   979  }
   980  
   981  func TestTrimFunc(t *testing.T) {
   982  	for _, tc := range trimFuncTests {
   983  		trimmers := []struct {
   984  			name string
   985  			trim func(s string, f func(r rune) bool) string
   986  			out  string
   987  		}{
   988  			{"TrimFunc", TrimFunc, tc.trimOut},
   989  			{"TrimLeftFunc", TrimLeftFunc, tc.leftOut},
   990  			{"TrimRightFunc", TrimRightFunc, tc.rightOut},
   991  		}
   992  		for _, trimmer := range trimmers {
   993  			actual := trimmer.trim(tc.in, tc.f.f)
   994  			if actual != trimmer.out {
   995  				t.Errorf("%s(%q, %q) = %q; want %q", trimmer.name, tc.in, tc.f.name, actual, trimmer.out)
   996  			}
   997  		}
   998  	}
   999  }
  1000  
  1001  var indexFuncTests = []struct {
  1002  	in          string
  1003  	f           predicate
  1004  	first, last int
  1005  }{
  1006  	{"", isValidRune, -1, -1},
  1007  	{"abc", isDigit, -1, -1},
  1008  	{"0123", isDigit, 0, 3},
  1009  	{"a1b", isDigit, 1, 1},
  1010  	{space, isSpace, 0, len(space) - 3}, // last rune in space is 3 bytes
  1011  	{"\u0e50\u0e5212hello34\u0e50\u0e51", isDigit, 0, 18},
  1012  	{"\u2C6F\u2C6F\u2C6F\u2C6FABCDhelloEF\u2C6F\u2C6FGH\u2C6F\u2C6F", isUpper, 0, 34},
  1013  	{"12\u0e50\u0e52hello34\u0e50\u0e51", not(isDigit), 8, 12},
  1014  
  1015  	// tests of invalid UTF-8
  1016  	{"\x801", isDigit, 1, 1},
  1017  	{"\x80abc", isDigit, -1, -1},
  1018  	{"\xc0a\xc0", isValidRune, 1, 1},
  1019  	{"\xc0a\xc0", not(isValidRune), 0, 2},
  1020  	{"\xc0☺\xc0", not(isValidRune), 0, 4},
  1021  	{"\xc0☺\xc0\xc0", not(isValidRune), 0, 5},
  1022  	{"ab\xc0a\xc0cd", not(isValidRune), 2, 4},
  1023  	{"a\xe0\x80cd", not(isValidRune), 1, 2},
  1024  	{"\x80\x80\x80\x80", not(isValidRune), 0, 3},
  1025  }
  1026  
  1027  func TestIndexFunc(t *testing.T) {
  1028  	for _, tc := range indexFuncTests {
  1029  		first := IndexFunc(tc.in, tc.f.f)
  1030  		if first != tc.first {
  1031  			t.Errorf("IndexFunc(%q, %s) = %d; want %d", tc.in, tc.f.name, first, tc.first)
  1032  		}
  1033  		last := LastIndexFunc(tc.in, tc.f.f)
  1034  		if last != tc.last {
  1035  			t.Errorf("LastIndexFunc(%q, %s) = %d; want %d", tc.in, tc.f.name, last, tc.last)
  1036  		}
  1037  	}
  1038  }
  1039  
  1040  func equal(m string, s1, s2 string, t *testing.T) bool {
  1041  	if s1 == s2 {
  1042  		return true
  1043  	}
  1044  	e1 := Split(s1, "")
  1045  	e2 := Split(s2, "")
  1046  	for i, c1 := range e1 {
  1047  		if i >= len(e2) {
  1048  			break
  1049  		}
  1050  		r1, _ := utf8.DecodeRuneInString(c1)
  1051  		r2, _ := utf8.DecodeRuneInString(e2[i])
  1052  		if r1 != r2 {
  1053  			t.Errorf("%s diff at %d: U+%04X U+%04X", m, i, r1, r2)
  1054  		}
  1055  	}
  1056  	return false
  1057  }
  1058  
  1059  func TestCaseConsistency(t *testing.T) {
  1060  	// Make a string of all the runes.
  1061  	numRunes := int(unicode.MaxRune + 1)
  1062  	if testing.Short() {
  1063  		numRunes = 1000
  1064  	}
  1065  	a := make([]rune, numRunes)
  1066  	for i := range a {
  1067  		a[i] = rune(i)
  1068  	}
  1069  	s := string(a)
  1070  	// convert the cases.
  1071  	upper := ToUpper(s)
  1072  	lower := ToLower(s)
  1073  
  1074  	// Consistency checks
  1075  	if n := utf8.RuneCountInString(upper); n != numRunes {
  1076  		t.Error("rune count wrong in upper:", n)
  1077  	}
  1078  	if n := utf8.RuneCountInString(lower); n != numRunes {
  1079  		t.Error("rune count wrong in lower:", n)
  1080  	}
  1081  	if !equal("ToUpper(upper)", ToUpper(upper), upper, t) {
  1082  		t.Error("ToUpper(upper) consistency fail")
  1083  	}
  1084  	if !equal("ToLower(lower)", ToLower(lower), lower, t) {
  1085  		t.Error("ToLower(lower) consistency fail")
  1086  	}
  1087  	/*
  1088  		  These fail because of non-one-to-oneness of the data, such as multiple
  1089  		  upper case 'I' mapping to 'i'.  We comment them out but keep them for
  1090  		  interest.
  1091  		  For instance: CAPITAL LETTER I WITH DOT ABOVE:
  1092  			unicode.ToUpper(unicode.ToLower('\u0130')) != '\u0130'
  1093  
  1094  		if !equal("ToUpper(lower)", ToUpper(lower), upper, t) {
  1095  			t.Error("ToUpper(lower) consistency fail");
  1096  		}
  1097  		if !equal("ToLower(upper)", ToLower(upper), lower, t) {
  1098  			t.Error("ToLower(upper) consistency fail");
  1099  		}
  1100  	*/
  1101  }
  1102  
  1103  var RepeatTests = []struct {
  1104  	in, out string
  1105  	count   int
  1106  }{
  1107  	{"", "", 0},
  1108  	{"", "", 1},
  1109  	{"", "", 2},
  1110  	{"-", "", 0},
  1111  	{"-", "-", 1},
  1112  	{"-", "----------", 10},
  1113  	{"abc ", "abc abc abc ", 3},
  1114  }
  1115  
  1116  func TestRepeat(t *testing.T) {
  1117  	for _, tt := range RepeatTests {
  1118  		a := Repeat(tt.in, tt.count)
  1119  		if !equal("Repeat(s)", a, tt.out, t) {
  1120  			t.Errorf("Repeat(%v, %d) = %v; want %v", tt.in, tt.count, a, tt.out)
  1121  			continue
  1122  		}
  1123  	}
  1124  }
  1125  
  1126  func repeat(s string, count int) (err error) {
  1127  	defer func() {
  1128  		if r := recover(); r != nil {
  1129  			switch v := r.(type) {
  1130  			case error:
  1131  				err = v
  1132  			default:
  1133  				err = fmt.Errorf("%s", v)
  1134  			}
  1135  		}
  1136  	}()
  1137  
  1138  	Repeat(s, count)
  1139  
  1140  	return
  1141  }
  1142  
  1143  // See Issue golang.org/issue/16237
  1144  func TestRepeatCatchesOverflow(t *testing.T) {
  1145  	tests := [...]struct {
  1146  		s      string
  1147  		count  int
  1148  		errStr string
  1149  	}{
  1150  		0: {"--", -2147483647, "negative"},
  1151  		1: {"", int(^uint(0) >> 1), ""},
  1152  		2: {"-", 10, ""},
  1153  		3: {"gopher", 0, ""},
  1154  		4: {"-", -1, "negative"},
  1155  		5: {"--", -102, "negative"},
  1156  		6: {string(make([]byte, 255)), int((^uint(0))/255 + 1), "overflow"},
  1157  	}
  1158  
  1159  	for i, tt := range tests {
  1160  		err := repeat(tt.s, tt.count)
  1161  		if tt.errStr == "" {
  1162  			if err != nil {
  1163  				t.Errorf("#%d panicked %v", i, err)
  1164  			}
  1165  			continue
  1166  		}
  1167  
  1168  		if err == nil || !Contains(err.Error(), tt.errStr) {
  1169  			t.Errorf("#%d expected %q got %q", i, tt.errStr, err)
  1170  		}
  1171  	}
  1172  }
  1173  
  1174  func runesEqual(a, b []rune) bool {
  1175  	if len(a) != len(b) {
  1176  		return false
  1177  	}
  1178  	for i, r := range a {
  1179  		if r != b[i] {
  1180  			return false
  1181  		}
  1182  	}
  1183  	return true
  1184  }
  1185  
  1186  var RunesTests = []struct {
  1187  	in    string
  1188  	out   []rune
  1189  	lossy bool
  1190  }{
  1191  	{"", []rune{}, false},
  1192  	{" ", []rune{32}, false},
  1193  	{"ABC", []rune{65, 66, 67}, false},
  1194  	{"abc", []rune{97, 98, 99}, false},
  1195  	{"\u65e5\u672c\u8a9e", []rune{26085, 26412, 35486}, false},
  1196  	{"ab\x80c", []rune{97, 98, 0xFFFD, 99}, true},
  1197  	{"ab\xc0c", []rune{97, 98, 0xFFFD, 99}, true},
  1198  }
  1199  
  1200  func TestRunes(t *testing.T) {
  1201  	for _, tt := range RunesTests {
  1202  		a := []rune(tt.in)
  1203  		if !runesEqual(a, tt.out) {
  1204  			t.Errorf("[]rune(%q) = %v; want %v", tt.in, a, tt.out)
  1205  			continue
  1206  		}
  1207  		if !tt.lossy {
  1208  			// can only test reassembly if we didn't lose information
  1209  			s := string(a)
  1210  			if s != tt.in {
  1211  				t.Errorf("string([]rune(%q)) = %x; want %x", tt.in, s, tt.in)
  1212  			}
  1213  		}
  1214  	}
  1215  }
  1216  
  1217  func TestReadByte(t *testing.T) {
  1218  	testStrings := []string{"", abcd, faces, commas}
  1219  	for _, s := range testStrings {
  1220  		reader := NewReader(s)
  1221  		if e := reader.UnreadByte(); e == nil {
  1222  			t.Errorf("Unreading %q at beginning: expected error", s)
  1223  		}
  1224  		var res bytes.Buffer
  1225  		for {
  1226  			b, e := reader.ReadByte()
  1227  			if e == io.EOF {
  1228  				break
  1229  			}
  1230  			if e != nil {
  1231  				t.Errorf("Reading %q: %s", s, e)
  1232  				break
  1233  			}
  1234  			res.WriteByte(b)
  1235  			// unread and read again
  1236  			e = reader.UnreadByte()
  1237  			if e != nil {
  1238  				t.Errorf("Unreading %q: %s", s, e)
  1239  				break
  1240  			}
  1241  			b1, e := reader.ReadByte()
  1242  			if e != nil {
  1243  				t.Errorf("Reading %q after unreading: %s", s, e)
  1244  				break
  1245  			}
  1246  			if b1 != b {
  1247  				t.Errorf("Reading %q after unreading: want byte %q, got %q", s, b, b1)
  1248  				break
  1249  			}
  1250  		}
  1251  		if res.String() != s {
  1252  			t.Errorf("Reader(%q).ReadByte() produced %q", s, res.String())
  1253  		}
  1254  	}
  1255  }
  1256  
  1257  func TestReadRune(t *testing.T) {
  1258  	testStrings := []string{"", abcd, faces, commas}
  1259  	for _, s := range testStrings {
  1260  		reader := NewReader(s)
  1261  		if e := reader.UnreadRune(); e == nil {
  1262  			t.Errorf("Unreading %q at beginning: expected error", s)
  1263  		}
  1264  		res := ""
  1265  		for {
  1266  			r, z, e := reader.ReadRune()
  1267  			if e == io.EOF {
  1268  				break
  1269  			}
  1270  			if e != nil {
  1271  				t.Errorf("Reading %q: %s", s, e)
  1272  				break
  1273  			}
  1274  			res += string(r)
  1275  			// unread and read again
  1276  			e = reader.UnreadRune()
  1277  			if e != nil {
  1278  				t.Errorf("Unreading %q: %s", s, e)
  1279  				break
  1280  			}
  1281  			r1, z1, e := reader.ReadRune()
  1282  			if e != nil {
  1283  				t.Errorf("Reading %q after unreading: %s", s, e)
  1284  				break
  1285  			}
  1286  			if r1 != r {
  1287  				t.Errorf("Reading %q after unreading: want rune %q, got %q", s, r, r1)
  1288  				break
  1289  			}
  1290  			if z1 != z {
  1291  				t.Errorf("Reading %q after unreading: want size %d, got %d", s, z, z1)
  1292  				break
  1293  			}
  1294  		}
  1295  		if res != s {
  1296  			t.Errorf("Reader(%q).ReadRune() produced %q", s, res)
  1297  		}
  1298  	}
  1299  }
  1300  
  1301  var UnreadRuneErrorTests = []struct {
  1302  	name string
  1303  	f    func(*Reader)
  1304  }{
  1305  	{"Read", func(r *Reader) { r.Read([]byte{0}) }},
  1306  	{"ReadByte", func(r *Reader) { r.ReadByte() }},
  1307  	{"UnreadRune", func(r *Reader) { r.UnreadRune() }},
  1308  	{"Seek", func(r *Reader) { r.Seek(0, io.SeekCurrent) }},
  1309  	{"WriteTo", func(r *Reader) { r.WriteTo(&bytes.Buffer{}) }},
  1310  }
  1311  
  1312  func TestUnreadRuneError(t *testing.T) {
  1313  	for _, tt := range UnreadRuneErrorTests {
  1314  		reader := NewReader("0123456789")
  1315  		if _, _, err := reader.ReadRune(); err != nil {
  1316  			// should not happen
  1317  			t.Fatal(err)
  1318  		}
  1319  		tt.f(reader)
  1320  		err := reader.UnreadRune()
  1321  		if err == nil {
  1322  			t.Errorf("Unreading after %s: expected error", tt.name)
  1323  		}
  1324  	}
  1325  }
  1326  
  1327  var ReplaceTests = []struct {
  1328  	in       string
  1329  	old, new string
  1330  	n        int
  1331  	out      string
  1332  }{
  1333  	{"hello", "l", "L", 0, "hello"},
  1334  	{"hello", "l", "L", -1, "heLLo"},
  1335  	{"hello", "x", "X", -1, "hello"},
  1336  	{"", "x", "X", -1, ""},
  1337  	{"radar", "r", "<r>", -1, "<r>ada<r>"},
  1338  	{"", "", "<>", -1, "<>"},
  1339  	{"banana", "a", "<>", -1, "b<>n<>n<>"},
  1340  	{"banana", "a", "<>", 1, "b<>nana"},
  1341  	{"banana", "a", "<>", 1000, "b<>n<>n<>"},
  1342  	{"banana", "an", "<>", -1, "b<><>a"},
  1343  	{"banana", "ana", "<>", -1, "b<>na"},
  1344  	{"banana", "", "<>", -1, "<>b<>a<>n<>a<>n<>a<>"},
  1345  	{"banana", "", "<>", 10, "<>b<>a<>n<>a<>n<>a<>"},
  1346  	{"banana", "", "<>", 6, "<>b<>a<>n<>a<>n<>a"},
  1347  	{"banana", "", "<>", 5, "<>b<>a<>n<>a<>na"},
  1348  	{"banana", "", "<>", 1, "<>banana"},
  1349  	{"banana", "a", "a", -1, "banana"},
  1350  	{"banana", "a", "a", 1, "banana"},
  1351  	{"☺☻☹", "", "<>", -1, "<>☺<>☻<>☹<>"},
  1352  }
  1353  
  1354  func TestReplace(t *testing.T) {
  1355  	for _, tt := range ReplaceTests {
  1356  		if s := Replace(tt.in, tt.old, tt.new, tt.n); s != tt.out {
  1357  			t.Errorf("Replace(%q, %q, %q, %d) = %q, want %q", tt.in, tt.old, tt.new, tt.n, s, tt.out)
  1358  		}
  1359  		if tt.n == -1 {
  1360  			s := ReplaceAll(tt.in, tt.old, tt.new)
  1361  			if s != tt.out {
  1362  				t.Errorf("ReplaceAll(%q, %q, %q) = %q, want %q", tt.in, tt.old, tt.new, s, tt.out)
  1363  			}
  1364  		}
  1365  	}
  1366  }
  1367  
  1368  var TitleTests = []struct {
  1369  	in, out string
  1370  }{
  1371  	{"", ""},
  1372  	{"a", "A"},
  1373  	{" aaa aaa aaa ", " Aaa Aaa Aaa "},
  1374  	{" Aaa Aaa Aaa ", " Aaa Aaa Aaa "},
  1375  	{"123a456", "123a456"},
  1376  	{"double-blind", "Double-Blind"},
  1377  	{"ÿøû", "Ÿøû"},
  1378  	{"with_underscore", "With_underscore"},
  1379  	{"unicode \xe2\x80\xa8 line separator", "Unicode \xe2\x80\xa8 Line Separator"},
  1380  }
  1381  
  1382  func TestTitle(t *testing.T) {
  1383  	for _, tt := range TitleTests {
  1384  		if s := Title(tt.in); s != tt.out {
  1385  			t.Errorf("Title(%q) = %q, want %q", tt.in, s, tt.out)
  1386  		}
  1387  	}
  1388  }
  1389  
  1390  var ContainsTests = []struct {
  1391  	str, substr string
  1392  	expected    bool
  1393  }{
  1394  	{"abc", "bc", true},
  1395  	{"abc", "bcd", false},
  1396  	{"abc", "", true},
  1397  	{"", "a", false},
  1398  
  1399  	// cases to cover code in runtime/asm_amd64.s:indexShortStr
  1400  	// 2-byte needle
  1401  	{"xxxxxx", "01", false},
  1402  	{"01xxxx", "01", true},
  1403  	{"xx01xx", "01", true},
  1404  	{"xxxx01", "01", true},
  1405  	{"01xxxxx"[1:], "01", false},
  1406  	{"xxxxx01"[:6], "01", false},
  1407  	// 3-byte needle
  1408  	{"xxxxxxx", "012", false},
  1409  	{"012xxxx", "012", true},
  1410  	{"xx012xx", "012", true},
  1411  	{"xxxx012", "012", true},
  1412  	{"012xxxxx"[1:], "012", false},
  1413  	{"xxxxx012"[:7], "012", false},
  1414  	// 4-byte needle
  1415  	{"xxxxxxxx", "0123", false},
  1416  	{"0123xxxx", "0123", true},
  1417  	{"xx0123xx", "0123", true},
  1418  	{"xxxx0123", "0123", true},
  1419  	{"0123xxxxx"[1:], "0123", false},
  1420  	{"xxxxx0123"[:8], "0123", false},
  1421  	// 5-7-byte needle
  1422  	{"xxxxxxxxx", "01234", false},
  1423  	{"01234xxxx", "01234", true},
  1424  	{"xx01234xx", "01234", true},
  1425  	{"xxxx01234", "01234", true},
  1426  	{"01234xxxxx"[1:], "01234", false},
  1427  	{"xxxxx01234"[:9], "01234", false},
  1428  	// 8-byte needle
  1429  	{"xxxxxxxxxxxx", "01234567", false},
  1430  	{"01234567xxxx", "01234567", true},
  1431  	{"xx01234567xx", "01234567", true},
  1432  	{"xxxx01234567", "01234567", true},
  1433  	{"01234567xxxxx"[1:], "01234567", false},
  1434  	{"xxxxx01234567"[:12], "01234567", false},
  1435  	// 9-15-byte needle
  1436  	{"xxxxxxxxxxxxx", "012345678", false},
  1437  	{"012345678xxxx", "012345678", true},
  1438  	{"xx012345678xx", "012345678", true},
  1439  	{"xxxx012345678", "012345678", true},
  1440  	{"012345678xxxxx"[1:], "012345678", false},
  1441  	{"xxxxx012345678"[:13], "012345678", false},
  1442  	// 16-byte needle
  1443  	{"xxxxxxxxxxxxxxxxxxxx", "0123456789ABCDEF", false},
  1444  	{"0123456789ABCDEFxxxx", "0123456789ABCDEF", true},
  1445  	{"xx0123456789ABCDEFxx", "0123456789ABCDEF", true},
  1446  	{"xxxx0123456789ABCDEF", "0123456789ABCDEF", true},
  1447  	{"0123456789ABCDEFxxxxx"[1:], "0123456789ABCDEF", false},
  1448  	{"xxxxx0123456789ABCDEF"[:20], "0123456789ABCDEF", false},
  1449  	// 17-31-byte needle
  1450  	{"xxxxxxxxxxxxxxxxxxxxx", "0123456789ABCDEFG", false},
  1451  	{"0123456789ABCDEFGxxxx", "0123456789ABCDEFG", true},
  1452  	{"xx0123456789ABCDEFGxx", "0123456789ABCDEFG", true},
  1453  	{"xxxx0123456789ABCDEFG", "0123456789ABCDEFG", true},
  1454  	{"0123456789ABCDEFGxxxxx"[1:], "0123456789ABCDEFG", false},
  1455  	{"xxxxx0123456789ABCDEFG"[:21], "0123456789ABCDEFG", false},
  1456  
  1457  	// partial match cases
  1458  	{"xx01x", "012", false},                             // 3
  1459  	{"xx0123x", "01234", false},                         // 5-7
  1460  	{"xx01234567x", "012345678", false},                 // 9-15
  1461  	{"xx0123456789ABCDEFx", "0123456789ABCDEFG", false}, // 17-31, issue 15679
  1462  }
  1463  
  1464  func TestContains(t *testing.T) {
  1465  	for _, ct := range ContainsTests {
  1466  		if Contains(ct.str, ct.substr) != ct.expected {
  1467  			t.Errorf("Contains(%s, %s) = %v, want %v",
  1468  				ct.str, ct.substr, !ct.expected, ct.expected)
  1469  		}
  1470  	}
  1471  }
  1472  
  1473  var ContainsAnyTests = []struct {
  1474  	str, substr string
  1475  	expected    bool
  1476  }{
  1477  	{"", "", false},
  1478  	{"", "a", false},
  1479  	{"", "abc", false},
  1480  	{"a", "", false},
  1481  	{"a", "a", true},
  1482  	{"aaa", "a", true},
  1483  	{"abc", "xyz", false},
  1484  	{"abc", "xcz", true},
  1485  	{"a☺b☻c☹d", "uvw☻xyz", true},
  1486  	{"aRegExp*", ".(|)*+?^$[]", true},
  1487  	{dots + dots + dots, " ", false},
  1488  }
  1489  
  1490  func TestContainsAny(t *testing.T) {
  1491  	for _, ct := range ContainsAnyTests {
  1492  		if ContainsAny(ct.str, ct.substr) != ct.expected {
  1493  			t.Errorf("ContainsAny(%s, %s) = %v, want %v",
  1494  				ct.str, ct.substr, !ct.expected, ct.expected)
  1495  		}
  1496  	}
  1497  }
  1498  
  1499  var ContainsRuneTests = []struct {
  1500  	str      string
  1501  	r        rune
  1502  	expected bool
  1503  }{
  1504  	{"", 'a', false},
  1505  	{"a", 'a', true},
  1506  	{"aaa", 'a', true},
  1507  	{"abc", 'y', false},
  1508  	{"abc", 'c', true},
  1509  	{"a☺b☻c☹d", 'x', false},
  1510  	{"a☺b☻c☹d", '☻', true},
  1511  	{"aRegExp*", '*', true},
  1512  }
  1513  
  1514  func TestContainsRune(t *testing.T) {
  1515  	for _, ct := range ContainsRuneTests {
  1516  		if ContainsRune(ct.str, ct.r) != ct.expected {
  1517  			t.Errorf("ContainsRune(%q, %q) = %v, want %v",
  1518  				ct.str, ct.r, !ct.expected, ct.expected)
  1519  		}
  1520  	}
  1521  }
  1522  
  1523  var EqualFoldTests = []struct {
  1524  	s, t string
  1525  	out  bool
  1526  }{
  1527  	{"abc", "abc", true},
  1528  	{"ABcd", "ABcd", true},
  1529  	{"123abc", "123ABC", true},
  1530  	{"αβδ", "ΑΒΔ", true},
  1531  	{"abc", "xyz", false},
  1532  	{"abc", "XYZ", false},
  1533  	{"abcdefghijk", "abcdefghijX", false},
  1534  	{"abcdefghijk", "abcdefghij\u212A", true},
  1535  	{"abcdefghijK", "abcdefghij\u212A", true},
  1536  	{"abcdefghijkz", "abcdefghij\u212Ay", false},
  1537  	{"abcdefghijKz", "abcdefghij\u212Ay", false},
  1538  	{"1", "2", false},
  1539  	{"utf-8", "US-ASCII", false},
  1540  }
  1541  
  1542  func TestEqualFold(t *testing.T) {
  1543  	for _, tt := range EqualFoldTests {
  1544  		if out := EqualFold(tt.s, tt.t); out != tt.out {
  1545  			t.Errorf("EqualFold(%#q, %#q) = %v, want %v", tt.s, tt.t, out, tt.out)
  1546  		}
  1547  		if out := EqualFold(tt.t, tt.s); out != tt.out {
  1548  			t.Errorf("EqualFold(%#q, %#q) = %v, want %v", tt.t, tt.s, out, tt.out)
  1549  		}
  1550  	}
  1551  }
  1552  
  1553  func BenchmarkEqualFold(b *testing.B) {
  1554  	for i := 0; i < b.N; i++ {
  1555  		for _, tt := range EqualFoldTests {
  1556  			if out := EqualFold(tt.s, tt.t); out != tt.out {
  1557  				b.Fatal("wrong result")
  1558  			}
  1559  		}
  1560  	}
  1561  }
  1562  
  1563  var CountTests = []struct {
  1564  	s, sep string
  1565  	num    int
  1566  }{
  1567  	{"", "", 1},
  1568  	{"", "notempty", 0},
  1569  	{"notempty", "", 9},
  1570  	{"smaller", "not smaller", 0},
  1571  	{"12345678987654321", "6", 2},
  1572  	{"611161116", "6", 3},
  1573  	{"notequal", "NotEqual", 0},
  1574  	{"equal", "equal", 1},
  1575  	{"abc1231231123q", "123", 3},
  1576  	{"11111", "11", 2},
  1577  }
  1578  
  1579  func TestCount(t *testing.T) {
  1580  	for _, tt := range CountTests {
  1581  		if num := Count(tt.s, tt.sep); num != tt.num {
  1582  			t.Errorf("Count(%q, %q) = %d, want %d", tt.s, tt.sep, num, tt.num)
  1583  		}
  1584  	}
  1585  }
  1586  
  1587  var cutTests = []struct {
  1588  	s, sep        string
  1589  	before, after string
  1590  	found         bool
  1591  }{
  1592  	{"abc", "b", "a", "c", true},
  1593  	{"abc", "a", "", "bc", true},
  1594  	{"abc", "c", "ab", "", true},
  1595  	{"abc", "abc", "", "", true},
  1596  	{"abc", "", "", "abc", true},
  1597  	{"abc", "d", "abc", "", false},
  1598  	{"", "d", "", "", false},
  1599  	{"", "", "", "", true},
  1600  }
  1601  
  1602  func TestCut(t *testing.T) {
  1603  	for _, tt := range cutTests {
  1604  		if before, after, found := Cut(tt.s, tt.sep); before != tt.before || after != tt.after || found != tt.found {
  1605  			t.Errorf("Cut(%q, %q) = %q, %q, %v, want %q, %q, %v", tt.s, tt.sep, before, after, found, tt.before, tt.after, tt.found)
  1606  		}
  1607  	}
  1608  }
  1609  
  1610  func makeBenchInputHard() string {
  1611  	tokens := [...]string{
  1612  		"<a>", "<p>", "<b>", "<strong>",
  1613  		"</a>", "</p>", "</b>", "</strong>",
  1614  		"hello", "world",
  1615  	}
  1616  	x := make([]byte, 0, 1<<20)
  1617  	for {
  1618  		i := rand.Intn(len(tokens))
  1619  		if len(x)+len(tokens[i]) >= 1<<20 {
  1620  			break
  1621  		}
  1622  		x = append(x, tokens[i]...)
  1623  	}
  1624  	return string(x)
  1625  }
  1626  
  1627  var benchInputHard = makeBenchInputHard()
  1628  
  1629  func benchmarkIndexHard(b *testing.B, sep string) {
  1630  	for i := 0; i < b.N; i++ {
  1631  		Index(benchInputHard, sep)
  1632  	}
  1633  }
  1634  
  1635  func benchmarkLastIndexHard(b *testing.B, sep string) {
  1636  	for i := 0; i < b.N; i++ {
  1637  		LastIndex(benchInputHard, sep)
  1638  	}
  1639  }
  1640  
  1641  func benchmarkCountHard(b *testing.B, sep string) {
  1642  	for i := 0; i < b.N; i++ {
  1643  		Count(benchInputHard, sep)
  1644  	}
  1645  }
  1646  
  1647  func BenchmarkIndexHard1(b *testing.B) { benchmarkIndexHard(b, "<>") }
  1648  func BenchmarkIndexHard2(b *testing.B) { benchmarkIndexHard(b, "</pre>") }
  1649  func BenchmarkIndexHard3(b *testing.B) { benchmarkIndexHard(b, "<b>hello world</b>") }
  1650  func BenchmarkIndexHard4(b *testing.B) {
  1651  	benchmarkIndexHard(b, "<pre><b>hello</b><strong>world</strong></pre>")
  1652  }
  1653  
  1654  func BenchmarkLastIndexHard1(b *testing.B) { benchmarkLastIndexHard(b, "<>") }
  1655  func BenchmarkLastIndexHard2(b *testing.B) { benchmarkLastIndexHard(b, "</pre>") }
  1656  func BenchmarkLastIndexHard3(b *testing.B) { benchmarkLastIndexHard(b, "<b>hello world</b>") }
  1657  
  1658  func BenchmarkCountHard1(b *testing.B) { benchmarkCountHard(b, "<>") }
  1659  func BenchmarkCountHard2(b *testing.B) { benchmarkCountHard(b, "</pre>") }
  1660  func BenchmarkCountHard3(b *testing.B) { benchmarkCountHard(b, "<b>hello world</b>") }
  1661  
  1662  var benchInputTorture = Repeat("ABC", 1<<10) + "123" + Repeat("ABC", 1<<10)
  1663  var benchNeedleTorture = Repeat("ABC", 1<<10+1)
  1664  
  1665  func BenchmarkIndexTorture(b *testing.B) {
  1666  	for i := 0; i < b.N; i++ {
  1667  		Index(benchInputTorture, benchNeedleTorture)
  1668  	}
  1669  }
  1670  
  1671  func BenchmarkCountTorture(b *testing.B) {
  1672  	for i := 0; i < b.N; i++ {
  1673  		Count(benchInputTorture, benchNeedleTorture)
  1674  	}
  1675  }
  1676  
  1677  func BenchmarkCountTortureOverlapping(b *testing.B) {
  1678  	A := Repeat("ABC", 1<<20)
  1679  	B := Repeat("ABC", 1<<10)
  1680  	for i := 0; i < b.N; i++ {
  1681  		Count(A, B)
  1682  	}
  1683  }
  1684  
  1685  func BenchmarkCountByte(b *testing.B) {
  1686  	indexSizes := []int{10, 32, 4 << 10, 4 << 20, 64 << 20}
  1687  	benchStr := Repeat(benchmarkString,
  1688  		(indexSizes[len(indexSizes)-1]+len(benchmarkString)-1)/len(benchmarkString))
  1689  	benchFunc := func(b *testing.B, benchStr string) {
  1690  		b.SetBytes(int64(len(benchStr)))
  1691  		for i := 0; i < b.N; i++ {
  1692  			Count(benchStr, "=")
  1693  		}
  1694  	}
  1695  	for _, size := range indexSizes {
  1696  		b.Run(fmt.Sprintf("%d", size), func(b *testing.B) {
  1697  			benchFunc(b, benchStr[:size])
  1698  		})
  1699  	}
  1700  
  1701  }
  1702  
  1703  var makeFieldsInput = func() string {
  1704  	x := make([]byte, 1<<20)
  1705  	// Input is ~10% space, ~10% 2-byte UTF-8, rest ASCII non-space.
  1706  	for i := range x {
  1707  		switch rand.Intn(10) {
  1708  		case 0:
  1709  			x[i] = ' '
  1710  		case 1:
  1711  			if i > 0 && x[i-1] == 'x' {
  1712  				copy(x[i-1:], "χ")
  1713  				break
  1714  			}
  1715  			fallthrough
  1716  		default:
  1717  			x[i] = 'x'
  1718  		}
  1719  	}
  1720  	return string(x)
  1721  }
  1722  
  1723  var makeFieldsInputASCII = func() string {
  1724  	x := make([]byte, 1<<20)
  1725  	// Input is ~10% space, rest ASCII non-space.
  1726  	for i := range x {
  1727  		if rand.Intn(10) == 0 {
  1728  			x[i] = ' '
  1729  		} else {
  1730  			x[i] = 'x'
  1731  		}
  1732  	}
  1733  	return string(x)
  1734  }
  1735  
  1736  var stringdata = []struct{ name, data string }{
  1737  	{"ASCII", makeFieldsInputASCII()},
  1738  	{"Mixed", makeFieldsInput()},
  1739  }
  1740  
  1741  func BenchmarkFields(b *testing.B) {
  1742  	for _, sd := range stringdata {
  1743  		b.Run(sd.name, func(b *testing.B) {
  1744  			for j := 1 << 4; j <= 1<<20; j <<= 4 {
  1745  				b.Run(fmt.Sprintf("%d", j), func(b *testing.B) {
  1746  					b.ReportAllocs()
  1747  					b.SetBytes(int64(j))
  1748  					data := sd.data[:j]
  1749  					for i := 0; i < b.N; i++ {
  1750  						Fields(data)
  1751  					}
  1752  				})
  1753  			}
  1754  		})
  1755  	}
  1756  }
  1757  
  1758  func BenchmarkFieldsFunc(b *testing.B) {
  1759  	for _, sd := range stringdata {
  1760  		b.Run(sd.name, func(b *testing.B) {
  1761  			for j := 1 << 4; j <= 1<<20; j <<= 4 {
  1762  				b.Run(fmt.Sprintf("%d", j), func(b *testing.B) {
  1763  					b.ReportAllocs()
  1764  					b.SetBytes(int64(j))
  1765  					data := sd.data[:j]
  1766  					for i := 0; i < b.N; i++ {
  1767  						FieldsFunc(data, unicode.IsSpace)
  1768  					}
  1769  				})
  1770  			}
  1771  		})
  1772  	}
  1773  }
  1774  
  1775  func BenchmarkSplitEmptySeparator(b *testing.B) {
  1776  	for i := 0; i < b.N; i++ {
  1777  		Split(benchInputHard, "")
  1778  	}
  1779  }
  1780  
  1781  func BenchmarkSplitSingleByteSeparator(b *testing.B) {
  1782  	for i := 0; i < b.N; i++ {
  1783  		Split(benchInputHard, "/")
  1784  	}
  1785  }
  1786  
  1787  func BenchmarkSplitMultiByteSeparator(b *testing.B) {
  1788  	for i := 0; i < b.N; i++ {
  1789  		Split(benchInputHard, "hello")
  1790  	}
  1791  }
  1792  
  1793  func BenchmarkSplitNSingleByteSeparator(b *testing.B) {
  1794  	for i := 0; i < b.N; i++ {
  1795  		SplitN(benchInputHard, "/", 10)
  1796  	}
  1797  }
  1798  
  1799  func BenchmarkSplitNMultiByteSeparator(b *testing.B) {
  1800  	for i := 0; i < b.N; i++ {
  1801  		SplitN(benchInputHard, "hello", 10)
  1802  	}
  1803  }
  1804  
  1805  func BenchmarkRepeat(b *testing.B) {
  1806  	s := "0123456789"
  1807  	for _, n := range []int{5, 10} {
  1808  		for _, c := range []int{1, 2, 6} {
  1809  			b.Run(fmt.Sprintf("%dx%d", n, c), func(b *testing.B) {
  1810  				for i := 0; i < b.N; i++ {
  1811  					Repeat(s[:n], c)
  1812  				}
  1813  			})
  1814  		}
  1815  	}
  1816  }
  1817  
  1818  func BenchmarkIndexAnyASCII(b *testing.B) {
  1819  	x := Repeat("#", 2048) // Never matches set
  1820  	cs := "0123456789abcdefghijklmnopqrstuvwxyz0123456789abcdefghijklmnopqrstuvwxyz"
  1821  	for k := 1; k <= 2048; k <<= 4 {
  1822  		for j := 1; j <= 64; j <<= 1 {
  1823  			b.Run(fmt.Sprintf("%d:%d", k, j), func(b *testing.B) {
  1824  				for i := 0; i < b.N; i++ {
  1825  					IndexAny(x[:k], cs[:j])
  1826  				}
  1827  			})
  1828  		}
  1829  	}
  1830  }
  1831  
  1832  func BenchmarkIndexAnyUTF8(b *testing.B) {
  1833  	x := Repeat("#", 2048) // Never matches set
  1834  	cs := "你好世界, hello world. 你好世界, hello world. 你好世界, hello world."
  1835  	for k := 1; k <= 2048; k <<= 4 {
  1836  		for j := 1; j <= 64; j <<= 1 {
  1837  			b.Run(fmt.Sprintf("%d:%d", k, j), func(b *testing.B) {
  1838  				for i := 0; i < b.N; i++ {
  1839  					IndexAny(x[:k], cs[:j])
  1840  				}
  1841  			})
  1842  		}
  1843  	}
  1844  }
  1845  
  1846  func BenchmarkLastIndexAnyASCII(b *testing.B) {
  1847  	x := Repeat("#", 2048) // Never matches set
  1848  	cs := "0123456789abcdefghijklmnopqrstuvwxyz0123456789abcdefghijklmnopqrstuvwxyz"
  1849  	for k := 1; k <= 2048; k <<= 4 {
  1850  		for j := 1; j <= 64; j <<= 1 {
  1851  			b.Run(fmt.Sprintf("%d:%d", k, j), func(b *testing.B) {
  1852  				for i := 0; i < b.N; i++ {
  1853  					LastIndexAny(x[:k], cs[:j])
  1854  				}
  1855  			})
  1856  		}
  1857  	}
  1858  }
  1859  
  1860  func BenchmarkLastIndexAnyUTF8(b *testing.B) {
  1861  	x := Repeat("#", 2048) // Never matches set
  1862  	cs := "你好世界, hello world. 你好世界, hello world. 你好世界, hello world."
  1863  	for k := 1; k <= 2048; k <<= 4 {
  1864  		for j := 1; j <= 64; j <<= 1 {
  1865  			b.Run(fmt.Sprintf("%d:%d", k, j), func(b *testing.B) {
  1866  				for i := 0; i < b.N; i++ {
  1867  					LastIndexAny(x[:k], cs[:j])
  1868  				}
  1869  			})
  1870  		}
  1871  	}
  1872  }
  1873  
  1874  func BenchmarkTrimASCII(b *testing.B) {
  1875  	cs := "0123456789abcdef"
  1876  	for k := 1; k <= 4096; k <<= 4 {
  1877  		for j := 1; j <= 16; j <<= 1 {
  1878  			b.Run(fmt.Sprintf("%d:%d", k, j), func(b *testing.B) {
  1879  				x := Repeat(cs[:j], k) // Always matches set
  1880  				for i := 0; i < b.N; i++ {
  1881  					Trim(x[:k], cs[:j])
  1882  				}
  1883  			})
  1884  		}
  1885  	}
  1886  }
  1887  
  1888  func BenchmarkTrimByte(b *testing.B) {
  1889  	x := "  the quick brown fox   "
  1890  	for i := 0; i < b.N; i++ {
  1891  		Trim(x, " ")
  1892  	}
  1893  }
  1894  
  1895  func BenchmarkIndexPeriodic(b *testing.B) {
  1896  	key := "aa"
  1897  	for _, skip := range [...]int{2, 4, 8, 16, 32, 64} {
  1898  		b.Run(fmt.Sprintf("IndexPeriodic%d", skip), func(b *testing.B) {
  1899  			s := Repeat("a"+Repeat(" ", skip-1), 1<<16/skip)
  1900  			for i := 0; i < b.N; i++ {
  1901  				Index(s, key)
  1902  			}
  1903  		})
  1904  	}
  1905  }
  1906  
  1907  func BenchmarkJoin(b *testing.B) {
  1908  	vals := []string{"red", "yellow", "pink", "green", "purple", "orange", "blue"}
  1909  	for l := 0; l <= len(vals); l++ {
  1910  		b.Run(strconv.Itoa(l), func(b *testing.B) {
  1911  			b.ReportAllocs()
  1912  			vals := vals[:l]
  1913  			for i := 0; i < b.N; i++ {
  1914  				Join(vals, " and ")
  1915  			}
  1916  		})
  1917  	}
  1918  }
  1919  
  1920  func BenchmarkTrimSpace(b *testing.B) {
  1921  	tests := []struct{ name, input string }{
  1922  		{"NoTrim", "typical"},
  1923  		{"ASCII", "  foo bar  "},
  1924  		{"SomeNonASCII", "    \u2000\t\r\n x\t\t\r\r\ny\n \u3000    "},
  1925  		{"JustNonASCII", "\u2000\u2000\u2000☺☺☺☺\u3000\u3000\u3000"},
  1926  	}
  1927  	for _, test := range tests {
  1928  		b.Run(test.name, func(b *testing.B) {
  1929  			for i := 0; i < b.N; i++ {
  1930  				TrimSpace(test.input)
  1931  			}
  1932  		})
  1933  	}
  1934  }
  1935  
  1936  var stringSink string
  1937  
  1938  func BenchmarkReplaceAll(b *testing.B) {
  1939  	b.ReportAllocs()
  1940  	for i := 0; i < b.N; i++ {
  1941  		stringSink = ReplaceAll("banana", "a", "<>")
  1942  	}
  1943  }
  1944  

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