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Source file src/strings/strings_test.go

Documentation: strings

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

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