src/pkg/bytes/bytes_test.go - go - Git at Google

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 package bytes_test

 import (
 	. "bytes"
 	"strings"
 	"testing"
 	"unicode"
 )

 func eq(a, b []string) bool {
 	if len(a) != len(b) {
 		return false
 	}
 	for i := 0; i < len(a); i++ {
 		if a[i] != b[i] {
 			return false
 		}
 	}
 	return true
 }

 func arrayOfString(a [][]byte) []string {
 	result := make([]string, len(a))
 	for j := 0; j < len(a); j++ {
 		result[j] = string(a[j])
 	}
 	return result
 }

 // For ease of reading, the test cases use strings that are converted to byte
 // arrays before invoking the functions.

 var abcd = "abcd"
 var faces = "☺☻☹"
 var commas = "1,2,3,4"
 var dots = "1....2....3....4"

 type BinOpTest struct {
 	a string
 	b string
 	i int
 }

 var comparetests = []BinOpTest{
 	BinOpTest{"", "", 0},
 	BinOpTest{"a", "", 1},
 	BinOpTest{"", "a", -1},
 	BinOpTest{"abc", "abc", 0},
 	BinOpTest{"ab", "abc", -1},
 	BinOpTest{"abc", "ab", 1},
 	BinOpTest{"x", "ab", 1},
 	BinOpTest{"ab", "x", -1},
 	BinOpTest{"x", "a", 1},
 	BinOpTest{"b", "x", -1},
 }

 func TestCompare(t *testing.T) {
 	for _, tt := range comparetests {
 		a := strings.Bytes(tt.a)
 		b := strings.Bytes(tt.b)
 		cmp := Compare(a, b)
 		eql := Equal(a, b)
 		if cmp != tt.i {
 			t.Errorf(`Compare(%q, %q) = %v`, tt.a, tt.b, cmp)
 		}
 		if eql != (tt.i == 0) {
 			t.Errorf(`Equal(%q, %q) = %v`, tt.a, tt.b, eql)
 		}
 	}
 }

 var indextests = []BinOpTest{
 	BinOpTest{"", "", 0},
 	BinOpTest{"a", "", 0},
 	BinOpTest{"", "a", -1},
 	BinOpTest{"abc", "abc", 0},
 	BinOpTest{"ab", "abc", -1},
 	BinOpTest{"abc", "bc", 1},
 	BinOpTest{"x", "ab", -1},
 	// one-byte tests for IndexByte
 	BinOpTest{"ab", "x", -1},
 	BinOpTest{"", "a", -1},
 	BinOpTest{"x", "a", -1},
 	BinOpTest{"x", "x", 0},
 	BinOpTest{"abc", "a", 0},
 	BinOpTest{"abc", "b", 1},
 	BinOpTest{"abc", "c", 2},
 	BinOpTest{"abc", "x", -1},
 }

 func TestIndex(t *testing.T) {
 	for _, tt := range indextests {
 		a := strings.Bytes(tt.a)
 		b := strings.Bytes(tt.b)
 		pos := Index(a, b)
 		if pos != tt.i {
 			t.Errorf(`Index(%q, %q) = %v`, tt.a, tt.b, pos)
 		}
 	}
 }

 func TestIndexByte(t *testing.T) {
 	for _, tt := range indextests {
 		if len(tt.b) != 1 {
 			continue
 		}
 		a := strings.Bytes(tt.a)
 		b := tt.b[0]
 		pos := IndexByte(a, b)
 		if pos != tt.i {
 			t.Errorf(`IndexByte(%q, '%c') = %v`, tt.a, b, pos)
 		}
 		posp := IndexBytePortable(a, b)
 		if posp != tt.i {
 			t.Errorf(`indexBytePortable(%q, '%c') = %v`, tt.a, b, posp)
 		}
 	}
 }

 func BenchmarkIndexByte4K(b *testing.B) { bmIndex(b, IndexByte, 4<<10) }

 func BenchmarkIndexByte4M(b *testing.B) { bmIndex(b, IndexByte, 4<<20) }

 func BenchmarkIndexByte64M(b *testing.B) { bmIndex(b, IndexByte, 64<<20) }

 func BenchmarkIndexBytePortable4K(b *testing.B) {
 	bmIndex(b, IndexBytePortable, 4<<10)
 }

 func BenchmarkIndexBytePortable4M(b *testing.B) {
 	bmIndex(b, IndexBytePortable, 4<<20)
 }

 func BenchmarkIndexBytePortable64M(b *testing.B) {
 	bmIndex(b, IndexBytePortable, 64<<20)
 }

 var bmbuf []byte

 func bmIndex(b *testing.B, index func([]byte, byte) int, n int) {
 	if len(bmbuf) < n {
 		bmbuf = make([]byte, n)
 	}
 	b.SetBytes(int64(n))
 	buf := bmbuf[0:n]
 	buf[n-1] = 'x'
 	for i := 0; i < b.N; i++ {
 		j := index(buf, 'x')
 		if j != n-1 {
 			panic("bad index", j)
 		}
 	}
 	buf[n-1] = '0'
 }

 type ExplodeTest struct {
 	s string
 	n int
 	a []string
 }

 var explodetests = []ExplodeTest{
 	ExplodeTest{abcd, 0, []string{"a", "b", "c", "d"}},
 	ExplodeTest{faces, 0, []string{"☺", "☻", "☹"}},
 	ExplodeTest{abcd, 2, []string{"a", "bcd"}},
 }

 func TestExplode(t *testing.T) {
 	for _, tt := range (explodetests) {
 		a := Split(strings.Bytes(tt.s), nil, tt.n)
 		result := arrayOfString(a)
 		if !eq(result, tt.a) {
 			t.Errorf(`Explode("%s", %d) = %v; want %v`, tt.s, tt.n, result, tt.a)
 			continue
 		}
 		s := Join(a, []byte{})
 		if string(s) != tt.s {
 			t.Errorf(`Join(Explode("%s", %d), "") = "%s"`, tt.s, tt.n, s)
 		}
 	}
 }


 type SplitTest struct {
 	s   string
 	sep string
 	n   int
 	a   []string
 }

 var splittests = []SplitTest{
 	SplitTest{abcd, "a", 0, []string{"", "bcd"}},
 	SplitTest{abcd, "z", 0, []string{"abcd"}},
 	SplitTest{abcd, "", 0, []string{"a", "b", "c", "d"}},
 	SplitTest{commas, ",", 0, []string{"1", "2", "3", "4"}},
 	SplitTest{dots, "...", 0, []string{"1", ".2", ".3", ".4"}},
 	SplitTest{faces, "☹", 0, []string{"☺☻", ""}},
 	SplitTest{faces, "~", 0, []string{faces}},
 	SplitTest{faces, "", 0, []string{"☺", "☻", "☹"}},
 	SplitTest{"1 2 3 4", " ", 3, []string{"1", "2", "3 4"}},
 	SplitTest{"1 2 3", " ", 3, []string{"1", "2", "3"}},
 	SplitTest{"1 2", " ", 3, []string{"1", "2"}},
 	SplitTest{"123", "", 2, []string{"1", "23"}},
 	SplitTest{"123", "", 17, []string{"1", "2", "3"}},
 }

 func TestSplit(t *testing.T) {
 	for _, tt := range splittests {
 		a := Split(strings.Bytes(tt.s), strings.Bytes(tt.sep), tt.n)
 		result := arrayOfString(a)
 		if !eq(result, tt.a) {
 			t.Errorf(`Split(%q, %q, %d) = %v; want %v`, tt.s, tt.sep, tt.n, result, tt.a)
 			continue
 		}
 		s := Join(a, strings.Bytes(tt.sep))
 		if string(s) != tt.s {
 			t.Errorf(`Join(Split(%q, %q, %d), %q) = %q`, tt.s, tt.sep, tt.n, tt.sep, s)
 		}
 	}
 }

 var splitaftertests = []SplitTest{
 	SplitTest{abcd, "a", 0, []string{"a", "bcd"}},
 	SplitTest{abcd, "z", 0, []string{"abcd"}},
 	SplitTest{abcd, "", 0, []string{"a", "b", "c", "d"}},
 	SplitTest{commas, ",", 0, []string{"1,", "2,", "3,", "4"}},
 	SplitTest{dots, "...", 0, []string{"1...", ".2...", ".3...", ".4"}},
 	SplitTest{faces, "☹", 0, []string{"☺☻☹", ""}},
 	SplitTest{faces, "~", 0, []string{faces}},
 	SplitTest{faces, "", 0, []string{"☺", "☻", "☹"}},
 	SplitTest{"1 2 3 4", " ", 3, []string{"1 ", "2 ", "3 4"}},
 	SplitTest{"1 2 3", " ", 3, []string{"1 ", "2 ", "3"}},
 	SplitTest{"1 2", " ", 3, []string{"1 ", "2"}},
 	SplitTest{"123", "", 2, []string{"1", "23"}},
 	SplitTest{"123", "", 17, []string{"1", "2", "3"}},
 }

 func TestSplitAfter(t *testing.T) {
 	for _, tt := range splitaftertests {
 		a := SplitAfter(strings.Bytes(tt.s), strings.Bytes(tt.sep), tt.n)
 		result := arrayOfString(a)
 		if !eq(result, tt.a) {
 			t.Errorf(`Split(%q, %q, %d) = %v; want %v`, tt.s, tt.sep, tt.n, result, tt.a)
 			continue
 		}
 		s := Join(a, nil)
 		if string(s) != tt.s {
 			t.Errorf(`Join(Split(%q, %q, %d), %q) = %q`, tt.s, tt.sep, tt.n, tt.sep, s)
 		}
 	}
 }

 type FieldsTest struct {
 	s string
 	a []string
 }

 var fieldstests = []FieldsTest{
 	FieldsTest{"", []string{}},
 	FieldsTest{" ", []string{}},
 	FieldsTest{" \t ", []string{}},
 	FieldsTest{"  abc  ", []string{"abc"}},
 	FieldsTest{"1 2 3 4", []string{"1", "2", "3", "4"}},
 	FieldsTest{"1  2  3  4", []string{"1", "2", "3", "4"}},
 	FieldsTest{"1\t\t2\t\t3\t4", []string{"1", "2", "3", "4"}},
 	FieldsTest{"1\u20002\u20013\u20024", []string{"1", "2", "3", "4"}},
 	FieldsTest{"\u2000\u2001\u2002", []string{}},
 	FieldsTest{"\n™\t™\n", []string{"™", "™"}},
 	FieldsTest{faces, []string{faces}},
 }

 func TestFields(t *testing.T) {
 	for _, tt := range fieldstests {
 		a := Fields(strings.Bytes(tt.s))
 		result := arrayOfString(a)
 		if !eq(result, tt.a) {
 			t.Errorf("Fields(%q) = %v; want %v", tt.s, a, tt.a)
 			continue
 		}
 	}
 }

 // Test case for any function which accepts and returns a byte array.
 // For ease of creation, we write the byte arrays as strings.
 type StringTest struct {
 	in, out string
 }

 var upperTests = []StringTest{
 	StringTest{"", ""},
 	StringTest{"abc", "ABC"},
 	StringTest{"AbC123", "ABC123"},
 	StringTest{"azAZ09_", "AZAZ09_"},
 	StringTest{"\u0250\u0250\u0250\u0250\u0250", "\u2C6F\u2C6F\u2C6F\u2C6F\u2C6F"}, // grows one byte per char
 }

 var lowerTests = []StringTest{
 	StringTest{"", ""},
 	StringTest{"abc", "abc"},
 	StringTest{"AbC123", "abc123"},
 	StringTest{"azAZ09_", "azaz09_"},
 	StringTest{"\u2C6D\u2C6D\u2C6D\u2C6D\u2C6D", "\u0251\u0251\u0251\u0251\u0251"}, // shrinks one byte per char
 }

 const space = "\t\v\r\f\n\u0085\u00a0\u2000\u3000"

 var trimSpaceTests = []StringTest{
 	StringTest{"", ""},
 	StringTest{"abc", "abc"},
 	StringTest{space + "abc" + space, "abc"},
 	StringTest{" ", ""},
 	StringTest{" \t\r\n \t\t\r\r\n\n ", ""},
 	StringTest{" \t\r\n x\t\t\r\r\n\n ", "x"},
 	StringTest{" \u2000\t\r\n x\t\t\r\r\ny\n \u3000", "x\t\t\r\r\ny"},
 	StringTest{"1 \t\r\n2", "1 \t\r\n2"},
 	StringTest{" x\x80", "x\x80"}, // invalid UTF-8 on end
 	StringTest{" x\xc0", "x\xc0"}, // invalid UTF-8 on end
 }

 // Bytes returns a new slice containing the bytes in s.
 // Borrowed from strings to avoid dependency.
 func Bytes(s string) []byte {
 	b := make([]byte, len(s))
 	for i := 0; i < len(s); i++ {
 		b[i] = s[i]
 	}
 	return b
 }

 // Execute f on each test case.  funcName should be the name of f; it's used
 // in failure reports.
 func runStringTests(t *testing.T, f func([]byte) []byte, funcName string, testCases []StringTest) {
 	for _, tc := range testCases {
 		actual := string(f(Bytes(tc.in)))
 		if actual != tc.out {
 			t.Errorf("%s(%q) = %q; want %q", funcName, tc.in, actual, tc.out)
 		}
 	}
 }

 func tenRunes(rune int) string {
 	r := make([]int, 10)
 	for i := range r {
 		r[i] = rune
 	}
 	return string(r)
 }

 // User-defined self-inverse mapping function
 func rot13(rune int) int {
 	step := 13
 	if rune >= 'a' && rune <= 'z' {
 		return ((rune - 'a' + step) % 26) + 'a'
 	}
 	if rune >= 'A' && rune <= 'Z' {
 		return ((rune - 'A' + step) % 26) + 'A'
 	}
 	return rune
 }

 func TestMap(t *testing.T) {
 	// Run a couple of awful growth/shrinkage tests
 	a := tenRunes('a')

 	// 1.  Grow.  This triggers two reallocations in Map.
 	maxRune := func(rune int) int { return unicode.MaxRune }
 	m := Map(maxRune, Bytes(a))
 	expect := tenRunes(unicode.MaxRune)
 	if string(m) != expect {
 		t.Errorf("growing: expected %q got %q", expect, m)
 	}

 	// 2. Shrink
 	minRune := func(rune int) int { return 'a' }
 	m = Map(minRune, Bytes(tenRunes(unicode.MaxRune)))
 	expect = a
 	if string(m) != expect {
 		t.Errorf("shrinking: expected %q got %q", expect, m)
 	}

 	// 3. Rot13
 	m = Map(rot13, Bytes("a to zed"))
 	expect = "n gb mrq"
 	if string(m) != expect {
 		t.Errorf("rot13: expected %q got %q", expect, m)
 	}

 	// 4. Rot13^2
 	m = Map(rot13, Map(rot13, Bytes("a to zed")))
 	expect = "a to zed"
 	if string(m) != expect {
 		t.Errorf("rot13: expected %q got %q", expect, m)
 	}

 	// 5. Drop
 	dropNotLatin := func(rune int) int {
 		if unicode.Is(unicode.Latin, rune) {
 			return rune
 		}
 		return -1
 	}
 	m = Map(dropNotLatin, Bytes("Hello, 세계"))
 	expect = "Hello"
 	if string(m) != expect {
 		t.Errorf("drop: expected %q got %q", expect, m)
 	}
 }

 func TestToUpper(t *testing.T) { runStringTests(t, ToUpper, "ToUpper", upperTests) }

 func TestToLower(t *testing.T) { runStringTests(t, ToLower, "ToLower", lowerTests) }

 func TestTrimSpace(t *testing.T) { runStringTests(t, TrimSpace, "TrimSpace", trimSpaceTests) }

 type AddTest struct {
 	s, t string
 	cap  int
 }

 var addtests = []AddTest{
 	AddTest{"", "", 0},
 	AddTest{"a", "", 1},
 	AddTest{"a", "b", 1},
 	AddTest{"abc", "def", 100},
 }

 func TestAdd(t *testing.T) {
 	for _, test := range addtests {
 		b := make([]byte, len(test.s), test.cap)
 		for i := 0; i < len(test.s); i++ {
 			b[i] = test.s[i]
 		}
 		b = Add(b, strings.Bytes(test.t))
 		if string(b) != test.s+test.t {
 			t.Errorf("Add(%q,%q) = %q", test.s, test.t, string(b))
 		}
 	}
 }

 func TestAddByte(t *testing.T) {
 	const N = 2e5
 	b := make([]byte, 0)
 	for i := 0; i < N; i++ {
 		b = AddByte(b, byte(i))
 	}
 	if len(b) != N {
 		t.Errorf("AddByte: too small; expected %d got %d", N, len(b))
 	}
 	for i, c := range b {
 		if c != byte(i) {
 			t.Fatalf("AddByte: b[%d] should be %d is %d", i, c, byte(i))
 		}
 	}
 }

 type RepeatTest struct {
 	in, out string
 	count   int
 }

 var RepeatTests = []RepeatTest{
 	RepeatTest{"", "", 0},
 	RepeatTest{"", "", 1},
 	RepeatTest{"", "", 2},
 	RepeatTest{"-", "", 0},
 	RepeatTest{"-", "-", 1},
 	RepeatTest{"-", "----------", 10},
 	RepeatTest{"abc ", "abc abc abc ", 3},
 }

 func TestRepeat(t *testing.T) {
 	for _, tt := range RepeatTests {
 		tin := strings.Bytes(tt.in)
 		tout := strings.Bytes(tt.out)
 		a := Repeat(tin, tt.count)
 		if !Equal(a, tout) {
 			t.Errorf("Repeat(%q, %d) = %q; want %q", tin, tt.count, a, tout)
 			continue
 		}
 	}
 }

 func runesEqual(a, b []int) bool {
 	if len(a) != len(b) {
 		return false
 	}
 	for i, r := range a {
 		if r != b[i] {
 			return false
 		}
 	}
 	return true
 }

 type RunesTest struct {
 	in    string
 	out   []int
 	lossy bool
 }

 var RunesTests = []RunesTest{
 	RunesTest{"", []int{}, false},
 	RunesTest{" ", []int{32}, false},
 	RunesTest{"ABC", []int{65, 66, 67}, false},
 	RunesTest{"abc", []int{97, 98, 99}, false},
 	RunesTest{"\u65e5\u672c\u8a9e", []int{26085, 26412, 35486}, false},
 	RunesTest{"ab\x80c", []int{97, 98, 0xFFFD, 99}, true},
 	RunesTest{"ab\xc0c", []int{97, 98, 0xFFFD, 99}, true},
 }

 func TestRunes(t *testing.T) {
 	for _, tt := range RunesTests {
 		tin := strings.Bytes(tt.in)
 		a := Runes(tin)
 		if !runesEqual(a, tt.out) {
 			t.Errorf("Runes(%q) = %v; want %v", tin, a, tt.out)
 			continue
 		}
 		if !tt.lossy {
 			// can only test reassembly if we didn't lose information
 			s := string(a)
 			if s != tt.in {
 				t.Errorf("string(Runes(%q)) = %x; want %x", tin, s, tin)
 			}
 		}
 	}
 }
	// Copyright 2009 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	package bytes_test

	import (
	. "bytes"
	"strings"
	"testing"
	"unicode"
	)

	func eq(a, b []string) bool {
	if len(a) != len(b) {
	return false
	}
	for i := 0; i < len(a); i++ {
	if a[i] != b[i] {
	return false
	}
	}
	return true
	}

	func arrayOfString(a [][]byte) []string {
	result := make([]string, len(a))
	for j := 0; j < len(a); j++ {
	result[j] = string(a[j])
	}
	return result
	}

	// For ease of reading, the test cases use strings that are converted to byte
	// arrays before invoking the functions.

	var abcd = "abcd"
	var faces = "☺☻☹"
	var commas = "1,2,3,4"
	var dots = "1....2....3....4"

	type BinOpTest struct {
	a string
	b string
	i int
	}

	var comparetests = []BinOpTest{
	BinOpTest{"", "", 0},
	BinOpTest{"a", "", 1},
	BinOpTest{"", "a", -1},
	BinOpTest{"abc", "abc", 0},
	BinOpTest{"ab", "abc", -1},
	BinOpTest{"abc", "ab", 1},
	BinOpTest{"x", "ab", 1},
	BinOpTest{"ab", "x", -1},
	BinOpTest{"x", "a", 1},
	BinOpTest{"b", "x", -1},
	}

	func TestCompare(t *testing.T) {
	for _, tt := range comparetests {
	a := strings.Bytes(tt.a)
	b := strings.Bytes(tt.b)
	cmp := Compare(a, b)
	eql := Equal(a, b)
	if cmp != tt.i {
	t.Errorf(`Compare(%q, %q) = %v`, tt.a, tt.b, cmp)
	}
	if eql != (tt.i == 0) {
	t.Errorf(`Equal(%q, %q) = %v`, tt.a, tt.b, eql)
	}
	}
	}

	var indextests = []BinOpTest{
	BinOpTest{"", "", 0},
	BinOpTest{"a", "", 0},
	BinOpTest{"", "a", -1},
	BinOpTest{"abc", "abc", 0},
	BinOpTest{"ab", "abc", -1},
	BinOpTest{"abc", "bc", 1},
	BinOpTest{"x", "ab", -1},
	// one-byte tests for IndexByte
	BinOpTest{"ab", "x", -1},
	BinOpTest{"", "a", -1},
	BinOpTest{"x", "a", -1},
	BinOpTest{"x", "x", 0},
	BinOpTest{"abc", "a", 0},
	BinOpTest{"abc", "b", 1},
	BinOpTest{"abc", "c", 2},
	BinOpTest{"abc", "x", -1},
	}

	func TestIndex(t *testing.T) {
	for _, tt := range indextests {
	a := strings.Bytes(tt.a)
	b := strings.Bytes(tt.b)
	pos := Index(a, b)
	if pos != tt.i {
	t.Errorf(`Index(%q, %q) = %v`, tt.a, tt.b, pos)
	}
	}
	}

	func TestIndexByte(t *testing.T) {
	for _, tt := range indextests {
	if len(tt.b) != 1 {
	continue
	}
	a := strings.Bytes(tt.a)
	b := tt.b[0]
	pos := IndexByte(a, b)
	if pos != tt.i {
	t.Errorf(`IndexByte(%q, '%c') = %v`, tt.a, b, pos)
	}
	posp := IndexBytePortable(a, b)
	if posp != tt.i {
	t.Errorf(`indexBytePortable(%q, '%c') = %v`, tt.a, b, posp)
	}
	}
	}

	func BenchmarkIndexByte4K(b *testing.B) { bmIndex(b, IndexByte, 4<<10) }

	func BenchmarkIndexByte4M(b *testing.B) { bmIndex(b, IndexByte, 4<<20) }

	func BenchmarkIndexByte64M(b *testing.B) { bmIndex(b, IndexByte, 64<<20) }

	func BenchmarkIndexBytePortable4K(b *testing.B) {
	bmIndex(b, IndexBytePortable, 4<<10)
	}

	func BenchmarkIndexBytePortable4M(b *testing.B) {
	bmIndex(b, IndexBytePortable, 4<<20)
	}

	func BenchmarkIndexBytePortable64M(b *testing.B) {
	bmIndex(b, IndexBytePortable, 64<<20)
	}

	var bmbuf []byte

	func bmIndex(b *testing.B, index func([]byte, byte) int, n int) {
	if len(bmbuf) < n {
	bmbuf = make([]byte, n)
	}
	b.SetBytes(int64(n))
	buf := bmbuf[0:n]
	buf[n-1] = 'x'
	for i := 0; i < b.N; i++ {
	j := index(buf, 'x')
	if j != n-1 {
	panic("bad index", j)
	}
	}
	buf[n-1] = '0'
	}

	type ExplodeTest struct {
	s string
	n int
	a []string
	}

	var explodetests = []ExplodeTest{
	ExplodeTest{abcd, 0, []string{"a", "b", "c", "d"}},
	ExplodeTest{faces, 0, []string{"☺", "☻", "☹"}},
	ExplodeTest{abcd, 2, []string{"a", "bcd"}},
	}

	func TestExplode(t *testing.T) {
	for _, tt := range (explodetests) {
	a := Split(strings.Bytes(tt.s), nil, tt.n)
	result := arrayOfString(a)
	if !eq(result, tt.a) {
	t.Errorf(`Explode("%s", %d) = %v; want %v`, tt.s, tt.n, result, tt.a)
	continue
	}
	s := Join(a, []byte{})
	if string(s) != tt.s {
	t.Errorf(`Join(Explode("%s", %d), "") = "%s"`, tt.s, tt.n, s)
	}
	}
	}


	type SplitTest struct {
	s string
	sep string
	n int
	a []string
	}

	var splittests = []SplitTest{
	SplitTest{abcd, "a", 0, []string{"", "bcd"}},
	SplitTest{abcd, "z", 0, []string{"abcd"}},
	SplitTest{abcd, "", 0, []string{"a", "b", "c", "d"}},
	SplitTest{commas, ",", 0, []string{"1", "2", "3", "4"}},
	SplitTest{dots, "...", 0, []string{"1", ".2", ".3", ".4"}},
	SplitTest{faces, "☹", 0, []string{"☺☻", ""}},
	SplitTest{faces, "~", 0, []string{faces}},
	SplitTest{faces, "", 0, []string{"☺", "☻", "☹"}},
	SplitTest{"1 2 3 4", " ", 3, []string{"1", "2", "3 4"}},
	SplitTest{"1 2 3", " ", 3, []string{"1", "2", "3"}},
	SplitTest{"1 2", " ", 3, []string{"1", "2"}},
	SplitTest{"123", "", 2, []string{"1", "23"}},
	SplitTest{"123", "", 17, []string{"1", "2", "3"}},
	}

	func TestSplit(t *testing.T) {
	for _, tt := range splittests {
	a := Split(strings.Bytes(tt.s), strings.Bytes(tt.sep), tt.n)
	result := arrayOfString(a)
	if !eq(result, tt.a) {
	t.Errorf(`Split(%q, %q, %d) = %v; want %v`, tt.s, tt.sep, tt.n, result, tt.a)
	continue
	}
	s := Join(a, strings.Bytes(tt.sep))
	if string(s) != tt.s {
	t.Errorf(`Join(Split(%q, %q, %d), %q) = %q`, tt.s, tt.sep, tt.n, tt.sep, s)
	}
	}
	}

	var splitaftertests = []SplitTest{
	SplitTest{abcd, "a", 0, []string{"a", "bcd"}},
	SplitTest{abcd, "z", 0, []string{"abcd"}},
	SplitTest{abcd, "", 0, []string{"a", "b", "c", "d"}},
	SplitTest{commas, ",", 0, []string{"1,", "2,", "3,", "4"}},
	SplitTest{dots, "...", 0, []string{"1...", ".2...", ".3...", ".4"}},
	SplitTest{faces, "☹", 0, []string{"☺☻☹", ""}},
	SplitTest{faces, "~", 0, []string{faces}},
	SplitTest{faces, "", 0, []string{"☺", "☻", "☹"}},
	SplitTest{"1 2 3 4", " ", 3, []string{"1 ", "2 ", "3 4"}},
	SplitTest{"1 2 3", " ", 3, []string{"1 ", "2 ", "3"}},
	SplitTest{"1 2", " ", 3, []string{"1 ", "2"}},
	SplitTest{"123", "", 2, []string{"1", "23"}},
	SplitTest{"123", "", 17, []string{"1", "2", "3"}},
	}

	func TestSplitAfter(t *testing.T) {
	for _, tt := range splitaftertests {
	a := SplitAfter(strings.Bytes(tt.s), strings.Bytes(tt.sep), tt.n)
	result := arrayOfString(a)
	if !eq(result, tt.a) {
	t.Errorf(`Split(%q, %q, %d) = %v; want %v`, tt.s, tt.sep, tt.n, result, tt.a)
	continue
	}
	s := Join(a, nil)
	if string(s) != tt.s {
	t.Errorf(`Join(Split(%q, %q, %d), %q) = %q`, tt.s, tt.sep, tt.n, tt.sep, s)
	}
	}
	}

	type FieldsTest struct {
	s string
	a []string
	}

	var fieldstests = []FieldsTest{
	FieldsTest{"", []string{}},
	FieldsTest{" ", []string{}},
	FieldsTest{" \t ", []string{}},
	FieldsTest{" abc ", []string{"abc"}},
	FieldsTest{"1 2 3 4", []string{"1", "2", "3", "4"}},
	FieldsTest{"1 2 3 4", []string{"1", "2", "3", "4"}},
	FieldsTest{"1\t\t2\t\t3\t4", []string{"1", "2", "3", "4"}},
	FieldsTest{"1\u20002\u20013\u20024", []string{"1", "2", "3", "4"}},
	FieldsTest{"\u2000\u2001\u2002", []string{}},
	FieldsTest{"\n™\t™\n", []string{"™", "™"}},
	FieldsTest{faces, []string{faces}},
	}

	func TestFields(t *testing.T) {
	for _, tt := range fieldstests {
	a := Fields(strings.Bytes(tt.s))
	result := arrayOfString(a)
	if !eq(result, tt.a) {
	t.Errorf("Fields(%q) = %v; want %v", tt.s, a, tt.a)
	continue
	}
	}
	}

	// Test case for any function which accepts and returns a byte array.
	// For ease of creation, we write the byte arrays as strings.
	type StringTest struct {
	in, out string
	}

	var upperTests = []StringTest{
	StringTest{"", ""},
	StringTest{"abc", "ABC"},
	StringTest{"AbC123", "ABC123"},
	StringTest{"azAZ09_", "AZAZ09_"},
	StringTest{"\u0250\u0250\u0250\u0250\u0250", "\u2C6F\u2C6F\u2C6F\u2C6F\u2C6F"}, // grows one byte per char
	}

	var lowerTests = []StringTest{
	StringTest{"", ""},
	StringTest{"abc", "abc"},
	StringTest{"AbC123", "abc123"},
	StringTest{"azAZ09_", "azaz09_"},
	StringTest{"\u2C6D\u2C6D\u2C6D\u2C6D\u2C6D", "\u0251\u0251\u0251\u0251\u0251"}, // shrinks one byte per char
	}

	const space = "\t\v\r\f\n\u0085\u00a0\u2000\u3000"

	var trimSpaceTests = []StringTest{
	StringTest{"", ""},
	StringTest{"abc", "abc"},
	StringTest{space + "abc" + space, "abc"},
	StringTest{" ", ""},
	StringTest{" \t\r\n \t\t\r\r\n\n ", ""},
	StringTest{" \t\r\n x\t\t\r\r\n\n ", "x"},
	StringTest{" \u2000\t\r\n x\t\t\r\r\ny\n \u3000", "x\t\t\r\r\ny"},
	StringTest{"1 \t\r\n2", "1 \t\r\n2"},
	StringTest{" x\x80", "x\x80"}, // invalid UTF-8 on end
	StringTest{" x\xc0", "x\xc0"}, // invalid UTF-8 on end
	}

	// Bytes returns a new slice containing the bytes in s.
	// Borrowed from strings to avoid dependency.
	func Bytes(s string) []byte {
	b := make([]byte, len(s))
	for i := 0; i < len(s); i++ {
	b[i] = s[i]
	}
	return b
	}

	// Execute f on each test case. funcName should be the name of f; it's used
	// in failure reports.
	func runStringTests(t *testing.T, f func([]byte) []byte, funcName string, testCases []StringTest) {
	for _, tc := range testCases {
	actual := string(f(Bytes(tc.in)))
	if actual != tc.out {
	t.Errorf("%s(%q) = %q; want %q", funcName, tc.in, actual, tc.out)
	}
	}
	}

	func tenRunes(rune int) string {
	r := make([]int, 10)
	for i := range r {
	r[i] = rune
	}
	return string(r)
	}

	// User-defined self-inverse mapping function
	func rot13(rune int) int {
	step := 13
	if rune >= 'a' && rune <= 'z' {
	return ((rune - 'a' + step) % 26) + 'a'
	}
	if rune >= 'A' && rune <= 'Z' {
	return ((rune - 'A' + step) % 26) + 'A'
	}
	return rune
	}

	func TestMap(t *testing.T) {
	// Run a couple of awful growth/shrinkage tests
	a := tenRunes('a')

	// 1. Grow. This triggers two reallocations in Map.
	maxRune := func(rune int) int { return unicode.MaxRune }
	m := Map(maxRune, Bytes(a))
	expect := tenRunes(unicode.MaxRune)
	if string(m) != expect {
	t.Errorf("growing: expected %q got %q", expect, m)
	}

	// 2. Shrink
	minRune := func(rune int) int { return 'a' }
	m = Map(minRune, Bytes(tenRunes(unicode.MaxRune)))
	expect = a
	if string(m) != expect {
	t.Errorf("shrinking: expected %q got %q", expect, m)
	}

	// 3. Rot13
	m = Map(rot13, Bytes("a to zed"))
	expect = "n gb mrq"
	if string(m) != expect {
	t.Errorf("rot13: expected %q got %q", expect, m)
	}

	// 4. Rot13^2
	m = Map(rot13, Map(rot13, Bytes("a to zed")))
	expect = "a to zed"
	if string(m) != expect {
	t.Errorf("rot13: expected %q got %q", expect, m)
	}

	// 5. Drop
	dropNotLatin := func(rune int) int {
	if unicode.Is(unicode.Latin, rune) {
	return rune
	}
	return -1
	}
	m = Map(dropNotLatin, Bytes("Hello, 세계"))
	expect = "Hello"
	if string(m) != expect {
	t.Errorf("drop: expected %q got %q", expect, m)
	}
	}

	func TestToUpper(t *testing.T) { runStringTests(t, ToUpper, "ToUpper", upperTests) }

	func TestToLower(t *testing.T) { runStringTests(t, ToLower, "ToLower", lowerTests) }

	func TestTrimSpace(t *testing.T) { runStringTests(t, TrimSpace, "TrimSpace", trimSpaceTests) }

	type AddTest struct {
	s, t string
	cap int
	}

	var addtests = []AddTest{
	AddTest{"", "", 0},
	AddTest{"a", "", 1},
	AddTest{"a", "b", 1},
	AddTest{"abc", "def", 100},
	}

	func TestAdd(t *testing.T) {
	for _, test := range addtests {
	b := make([]byte, len(test.s), test.cap)
	for i := 0; i < len(test.s); i++ {
	b[i] = test.s[i]
	}
	b = Add(b, strings.Bytes(test.t))
	if string(b) != test.s+test.t {
	t.Errorf("Add(%q,%q) = %q", test.s, test.t, string(b))
	}
	}
	}

	func TestAddByte(t *testing.T) {
	const N = 2e5
	b := make([]byte, 0)
	for i := 0; i < N; i++ {
	b = AddByte(b, byte(i))
	}
	if len(b) != N {
	t.Errorf("AddByte: too small; expected %d got %d", N, len(b))
	}
	for i, c := range b {
	if c != byte(i) {
	t.Fatalf("AddByte: b[%d] should be %d is %d", i, c, byte(i))
	}
	}
	}

	type RepeatTest struct {
	in, out string
	count int
	}

	var RepeatTests = []RepeatTest{
	RepeatTest{"", "", 0},
	RepeatTest{"", "", 1},
	RepeatTest{"", "", 2},
	RepeatTest{"-", "", 0},
	RepeatTest{"-", "-", 1},
	RepeatTest{"-", "----------", 10},
	RepeatTest{"abc ", "abc abc abc ", 3},
	}

	func TestRepeat(t *testing.T) {
	for _, tt := range RepeatTests {
	tin := strings.Bytes(tt.in)
	tout := strings.Bytes(tt.out)
	a := Repeat(tin, tt.count)
	if !Equal(a, tout) {
	t.Errorf("Repeat(%q, %d) = %q; want %q", tin, tt.count, a, tout)
	continue
	}
	}
	}

	func runesEqual(a, b []int) bool {
	if len(a) != len(b) {
	return false
	}
	for i, r := range a {
	if r != b[i] {
	return false
	}
	}
	return true
	}

	type RunesTest struct {
	in string
	out []int
	lossy bool
	}

	var RunesTests = []RunesTest{
	RunesTest{"", []int{}, false},
	RunesTest{" ", []int{32}, false},
	RunesTest{"ABC", []int{65, 66, 67}, false},
	RunesTest{"abc", []int{97, 98, 99}, false},
	RunesTest{"\u65e5\u672c\u8a9e", []int{26085, 26412, 35486}, false},
	RunesTest{"ab\x80c", []int{97, 98, 0xFFFD, 99}, true},
	RunesTest{"ab\xc0c", []int{97, 98, 0xFFFD, 99}, true},
	}

	func TestRunes(t *testing.T) {
	for _, tt := range RunesTests {
	tin := strings.Bytes(tt.in)
	a := Runes(tin)
	if !runesEqual(a, tt.out) {
	t.Errorf("Runes(%q) = %v; want %v", tin, a, tt.out)
	continue
	}
	if !tt.lossy {
	// can only test reassembly if we didn't lose information
	s := string(a)
	if s != tt.in {
	t.Errorf("string(Runes(%q)) = %x; want %x", tin, s, tin)
	}
	}
	}
	}