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// 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"
        "reflect"
        "testing"
        "unicode"
        "unicode/utf8"
)

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{
        {"", "", 0},
        {"a", "", 1},
        {"", "a", -1},
        {"abc", "abc", 0},
        {"ab", "abc", -1},
        {"abc", "ab", 1},
        {"x", "ab", 1},
        {"ab", "x", -1},
        {"x", "a", 1},
        {"b", "x", -1},
}

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

var indexTests = []BinOpTest{
        {"", "", 0},
        {"", "a", -1},
        {"", "foo", -1},
        {"fo", "foo", -1},
        {"foo", "foo", 0},
        {"oofofoofooo", "f", 2},
        {"oofofoofooo", "foo", 4},
        {"barfoobarfoo", "foo", 3},
        {"foo", "", 0},
        {"foo", "o", 1},
        {"abcABCabc", "A", 3},
        // cases with one byte strings - test IndexByte and special case in Index()
        {"", "a", -1},
        {"x", "a", -1},
        {"x", "x", 0},
        {"abc", "a", 0},
        {"abc", "b", 1},
        {"abc", "c", 2},
        {"abc", "x", -1},
        {"barfoobarfooyyyzzzyyyzzzyyyzzzyyyxxxzzzyyy", "x", 33},
        {"foofyfoobarfoobar", "y", 4},
        {"oooooooooooooooooooooo", "r", -1},
}

var lastIndexTests = []BinOpTest{
        {"", "", 0},
        {"", "a", -1},
        {"", "foo", -1},
        {"fo", "foo", -1},
        {"foo", "foo", 0},
        {"foo", "f", 0},
        {"oofofoofooo", "f", 7},
        {"oofofoofooo", "foo", 7},
        {"barfoobarfoo", "foo", 9},
        {"foo", "", 3},
        {"foo", "o", 2},
        {"abcABCabc", "A", 3},
        {"abcABCabc", "a", 6},
}

var indexAnyTests = []BinOpTest{
        {"", "", -1},
        {"", "a", -1},
        {"", "abc", -1},
        {"a", "", -1},
        {"a", "a", 0},
        {"aaa", "a", 0},
        {"abc", "xyz", -1},
        {"abc", "xcz", 2},
        {"ab☺c", "x☺yz", 2},
        {"aRegExp*", ".(|)*+?^$[]", 7},
        {dots + dots + dots, " ", -1},
}

var lastIndexAnyTests = []BinOpTest{
        {"", "", -1},
        {"", "a", -1},
        {"", "abc", -1},
        {"a", "", -1},
        {"a", "a", 0},
        {"aaa", "a", 2},
        {"abc", "xyz", -1},
        {"abc", "ab", 1},
        {"a☺b☻c☹d", "uvw☻xyz", 2 + len("☺")},
        {"a.RegExp*", ".(|)*+?^$[]", 8},
        {dots + dots + dots, " ", -1},
}

var indexRuneTests = []BinOpTest{
        {"", "a", -1},
        {"", "☺", -1},
        {"foo", "☹", -1},
        {"foo", "o", 1},
        {"foo☺bar", "☺", 3},
        {"foo☺☻☹bar", "☹", 9},
}

// Execute f on each test case.  funcName should be the name of f; it's used
// in failure reports.
func runIndexTests(t *testing.T, f func(s, sep []byte) int, funcName string, testCases []BinOpTest) {
        for _, test := range testCases {
                a := []byte(test.a)
                b := []byte(test.b)
                actual := f(a, b)
                if actual != test.i {
                        t.Errorf("%s(%q,%q) = %v; want %v", funcName, a, b, actual, test.i)
                }
        }
}

func runIndexAnyTests(t *testing.T, f func(s []byte, chars string) int, funcName string, testCases []BinOpTest) {
        for _, test := range testCases {
                a := []byte(test.a)
                actual := f(a, test.b)
                if actual != test.i {
                        t.Errorf("%s(%q,%q) = %v; want %v", funcName, a, test.b, actual, test.i)
                }
        }
}

func TestIndex(t *testing.T)     { runIndexTests(t, Index, "Index", indexTests) }
func TestLastIndex(t *testing.T) { runIndexTests(t, LastIndex, "LastIndex", lastIndexTests) }
func TestIndexAny(t *testing.T)  { runIndexAnyTests(t, IndexAny, "IndexAny", indexAnyTests) }
func TestLastIndexAny(t *testing.T) {
        runIndexAnyTests(t, LastIndexAny, "LastIndexAny", lastIndexAnyTests)
}

func TestIndexByte(t *testing.T) {
        for _, tt := range indexTests {
                if len(tt.b) != 1 {
                        continue
                }
                a := []byte(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)
                }
        }
}

// test a larger buffer with different sizes and alignments
func TestIndexByteBig(t *testing.T) {
        var n = 1024
        if testing.Short() {
                n = 128
        }
        b := make([]byte, n)
        for i := 0; i < n; i++ {
                // different start alignments
                b1 := b[i:]
                for j := 0; j < len(b1); j++ {
                        b1[j] = 'x'
                        pos := IndexByte(b1, 'x')
                        if pos != j {
                                t.Errorf("IndexByte(%q, 'x') = %v", b1, pos)
                        }
                        b1[j] = 0
                        pos = IndexByte(b1, 'x')
                        if pos != -1 {
                                t.Errorf("IndexByte(%q, 'x') = %v", b1, pos)
                        }
                }
                // different end alignments
                b1 = b[:i]
                for j := 0; j < len(b1); j++ {
                        b1[j] = 'x'
                        pos := IndexByte(b1, 'x')
                        if pos != j {
                                t.Errorf("IndexByte(%q, 'x') = %v", b1, pos)
                        }
                        b1[j] = 0
                        pos = IndexByte(b1, 'x')
                        if pos != -1 {
                                t.Errorf("IndexByte(%q, 'x') = %v", b1, pos)
                        }
                }
                // different start and end alignments
                b1 = b[i/2 : n-(i+1)/2]
                for j := 0; j < len(b1); j++ {
                        b1[j] = 'x'
                        pos := IndexByte(b1, 'x')
                        if pos != j {
                                t.Errorf("IndexByte(%q, 'x') = %v", b1, pos)
                        }
                        b1[j] = 0
                        pos = IndexByte(b1, 'x')
                        if pos != -1 {
                                t.Errorf("IndexByte(%q, 'x') = %v", b1, pos)
                        }
                }
        }
}

func TestIndexRune(t *testing.T) {
        for _, tt := range indexRuneTests {
                a := []byte(tt.a)
                r, _ := utf8.DecodeRuneInString(tt.b)
                pos := IndexRune(a, r)
                if pos != tt.i {
                        t.Errorf(`IndexRune(%q, '%c') = %v`, tt.a, r, pos)
                }
        }
}

var bmbuf []byte

func BenchmarkIndexByte32(b *testing.B)          { bmIndexByte(b, IndexByte, 32) }
func BenchmarkIndexByte4K(b *testing.B)          { bmIndexByte(b, IndexByte, 4<<10) }
func BenchmarkIndexByte4M(b *testing.B)          { bmIndexByte(b, IndexByte, 4<<20) }
func BenchmarkIndexByte64M(b *testing.B)         { bmIndexByte(b, IndexByte, 64<<20) }
func BenchmarkIndexBytePortable32(b *testing.B)  { bmIndexByte(b, IndexBytePortable, 32) }
func BenchmarkIndexBytePortable4K(b *testing.B)  { bmIndexByte(b, IndexBytePortable, 4<<10) }
func BenchmarkIndexBytePortable4M(b *testing.B)  { bmIndexByte(b, IndexBytePortable, 4<<20) }
func BenchmarkIndexBytePortable64M(b *testing.B) { bmIndexByte(b, IndexBytePortable, 64<<20) }

func bmIndexByte(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 {
                        b.Fatal("bad index", j)
                }
        }
        buf[n-1] = '\x00'
}

func BenchmarkEqual32(b *testing.B)          { bmEqual(b, Equal, 32) }
func BenchmarkEqual4K(b *testing.B)          { bmEqual(b, Equal, 4<<10) }
func BenchmarkEqual4M(b *testing.B)          { bmEqual(b, Equal, 4<<20) }
func BenchmarkEqual64M(b *testing.B)         { bmEqual(b, Equal, 64<<20) }
func BenchmarkEqualPort32(b *testing.B)      { bmEqual(b, EqualPortable, 32) }
func BenchmarkEqualPort4K(b *testing.B)      { bmEqual(b, EqualPortable, 4<<10) }
func BenchmarkEqualPortable4M(b *testing.B)  { bmEqual(b, EqualPortable, 4<<20) }
func BenchmarkEqualPortable64M(b *testing.B) { bmEqual(b, EqualPortable, 64<<20) }

func bmEqual(b *testing.B, equal func([]byte, []byte) bool, n int) {
        if len(bmbuf) < 2*n {
                bmbuf = make([]byte, 2*n)
        }
        b.SetBytes(int64(n))
        buf1 := bmbuf[0:n]
        buf2 := bmbuf[n : 2*n]
        buf1[n-1] = 'x'
        buf2[n-1] = 'x'
        for i := 0; i < b.N; i++ {
                eq := equal(buf1, buf2)
                if !eq {
                        b.Fatal("bad equal")
                }
        }
        buf1[n-1] = '\x00'
        buf2[n-1] = '\x00'
}

func BenchmarkIndex32(b *testing.B)  { bmIndex(b, Index, 32) }
func BenchmarkIndex4K(b *testing.B)  { bmIndex(b, Index, 4<<10) }
func BenchmarkIndex4M(b *testing.B)  { bmIndex(b, Index, 4<<20) }
func BenchmarkIndex64M(b *testing.B) { bmIndex(b, Index, 64<<20) }

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, buf[n-7:])
                if j != n-7 {
                        b.Fatal("bad index", j)
                }
        }
        buf[n-1] = '\x00'
}

func BenchmarkIndexEasy32(b *testing.B)  { bmIndexEasy(b, Index, 32) }
func BenchmarkIndexEasy4K(b *testing.B)  { bmIndexEasy(b, Index, 4<<10) }
func BenchmarkIndexEasy4M(b *testing.B)  { bmIndexEasy(b, Index, 4<<20) }
func BenchmarkIndexEasy64M(b *testing.B) { bmIndexEasy(b, Index, 64<<20) }

func bmIndexEasy(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'
        buf[n-7] = 'x'
        for i := 0; i < b.N; i++ {
                j := index(buf, buf[n-7:])
                if j != n-7 {
                        b.Fatal("bad index", j)
                }
        }
        buf[n-1] = '\x00'
        buf[n-7] = '\x00'
}

func BenchmarkCount32(b *testing.B)  { bmCount(b, Count, 32) }
func BenchmarkCount4K(b *testing.B)  { bmCount(b, Count, 4<<10) }
func BenchmarkCount4M(b *testing.B)  { bmCount(b, Count, 4<<20) }
func BenchmarkCount64M(b *testing.B) { bmCount(b, Count, 64<<20) }

func bmCount(b *testing.B, count 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 := count(buf, buf[n-7:])
                if j != 1 {
                        b.Fatal("bad count", j)
                }
        }
        buf[n-1] = '\x00'
}

func BenchmarkCountEasy32(b *testing.B)  { bmCountEasy(b, Count, 32) }
func BenchmarkCountEasy4K(b *testing.B)  { bmCountEasy(b, Count, 4<<10) }
func BenchmarkCountEasy4M(b *testing.B)  { bmCountEasy(b, Count, 4<<20) }
func BenchmarkCountEasy64M(b *testing.B) { bmCountEasy(b, Count, 64<<20) }

func bmCountEasy(b *testing.B, count 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'
        buf[n-7] = 'x'
        for i := 0; i < b.N; i++ {
                j := count(buf, buf[n-7:])
                if j != 1 {
                        b.Fatal("bad count", j)
                }
        }
        buf[n-1] = '\x00'
        buf[n-7] = '\x00'
}

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

var explodetests = []ExplodeTest{
        {"", -1, []string{}},
        {abcd, -1, []string{"a", "b", "c", "d"}},
        {faces, -1, []string{"☺", "☻", "☹"}},
        {abcd, 2, []string{"a", "bcd"}},
}

func TestExplode(t *testing.T) {
        for _, tt := range explodetests {
                a := SplitN([]byte(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{
        {abcd, "a", 0, nil},
        {abcd, "a", -1, []string{"", "bcd"}},
        {abcd, "z", -1, []string{"abcd"}},
        {abcd, "", -1, []string{"a", "b", "c", "d"}},
        {commas, ",", -1, []string{"1", "2", "3", "4"}},
        {dots, "...", -1, []string{"1", ".2", ".3", ".4"}},
        {faces, "☹", -1, []string{"☺☻", ""}},
        {faces, "~", -1, []string{faces}},
        {faces, "", -1, []string{"☺", "☻", "☹"}},
        {"1 2 3 4", " ", 3, []string{"1", "2", "3 4"}},
        {"1 2", " ", 3, []string{"1", "2"}},
        {"123", "", 2, []string{"1", "23"}},
        {"123", "", 17, []string{"1", "2", "3"}},
}

func TestSplit(t *testing.T) {
        for _, tt := range splittests {
                a := SplitN([]byte(tt.s), []byte(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
                }
                if tt.n == 0 {
                        continue
                }
                s := Join(a, []byte(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)
                }
                if tt.n < 0 {
                        b := Split([]byte(tt.s), []byte(tt.sep))
                        if !reflect.DeepEqual(a, b) {
                                t.Errorf("Split disagrees withSplitN(%q, %q, %d) = %v; want %v", tt.s, tt.sep, tt.n, b, a)
                        }
                }
        }
}

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

func TestSplitAfter(t *testing.T) {
        for _, tt := range splitaftertests {
                a := SplitAfterN([]byte(tt.s), []byte(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)
                }
                if tt.n < 0 {
                        b := SplitAfter([]byte(tt.s), []byte(tt.sep))
                        if !reflect.DeepEqual(a, b) {
                                t.Errorf("SplitAfter disagrees withSplitAfterN(%q, %q, %d) = %v; want %v", tt.s, tt.sep, tt.n, b, a)
                        }
                }
        }
}

type FieldsTest struct {
        s string
        a []string
}

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

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

func TestFieldsFunc(t *testing.T) {
        pred := func(c rune) bool { return c == 'X' }
        var fieldsFuncTests = []FieldsTest{
                {"", []string{}},
                {"XX", []string{}},
                {"XXhiXXX", []string{"hi"}},
                {"aXXbXXXcX", []string{"a", "b", "c"}},
        }
        for _, tt := range fieldsFuncTests {
                a := FieldsFunc([]byte(tt.s), pred)
                result := arrayOfString(a)
                if !eq(result, tt.a) {
                        t.Errorf("FieldsFunc(%q) = %v, want %v", tt.s, a, tt.a)
                }
        }
}

// 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{
        {"", ""},
        {"abc", "ABC"},
        {"AbC123", "ABC123"},
        {"azAZ09_", "AZAZ09_"},
        {"\u0250\u0250\u0250\u0250\u0250", "\u2C6F\u2C6F\u2C6F\u2C6F\u2C6F"}, // grows one byte per char
}

var lowerTests = []StringTest{
        {"", ""},
        {"abc", "abc"},
        {"AbC123", "abc123"},
        {"azAZ09_", "azaz09_"},
        {"\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{
        {"", ""},
        {"abc", "abc"},
        {space + "abc" + space, "abc"},
        {" ", ""},
        {" \t\r\n \t\t\r\r\n\n ", ""},
        {" \t\r\n x\t\t\r\r\n\n ", "x"},
        {" \u2000\t\r\n x\t\t\r\r\ny\n \u3000", "x\t\t\r\r\ny"},
        {"1 \t\r\n2", "1 \t\r\n2"},
        {" x\x80", "x\x80"},
        {" x\xc0", "x\xc0"},
        {"x \xc0\xc0 ", "x \xc0\xc0"},
        {"x \xc0", "x \xc0"},
        {"x \xc0 ", "x \xc0"},
        {"x \xc0\xc0 ", "x \xc0\xc0"},
        {"x ☺\xc0\xc0 ", "x ☺\xc0\xc0"},
        {"x ☺ ", "x ☺"},
}

// 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([]byte(tc.in)))
                if actual != tc.out {
                        t.Errorf("%s(%q) = %q; want %q", funcName, tc.in, actual, tc.out)
                }
        }
}

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

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

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(r rune) rune { return unicode.MaxRune }
        m := Map(maxRune, []byte(a))
        expect := tenRunes(unicode.MaxRune)
        if string(m) != expect {
                t.Errorf("growing: expected %q got %q", expect, m)
        }

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

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

        // 5. Drop
        dropNotLatin := func(r rune) rune {
                if unicode.Is(unicode.Latin, r) {
                        return r
                }
                return -1
        }
        m = Map(dropNotLatin, []byte("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 RepeatTest struct {
        in, out string
        count   int
}

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

func TestRepeat(t *testing.T) {
        for _, tt := range RepeatTests {
                tin := []byte(tt.in)
                tout := []byte(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 []rune) 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   []rune
        lossy bool
}

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

func TestRunes(t *testing.T) {
        for _, tt := range RunesTests {
                tin := []byte(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)
                        }
                }
        }
}

type TrimTest struct {
        f               string
        in, cutset, out string
}

var trimTests = []TrimTest{
        {"Trim", "abba", "a", "bb"},
        {"Trim", "abba", "ab", ""},
        {"TrimLeft", "abba", "ab", ""},
        {"TrimRight", "abba", "ab", ""},
        {"TrimLeft", "abba", "a", "bba"},
        {"TrimRight", "abba", "a", "abb"},
        {"Trim", "<tag>", "<>", "tag"},
        {"Trim", "* listitem", " *", "listitem"},
        {"Trim", `"quote"`, `"`, "quote"},
        {"Trim", "\u2C6F\u2C6F\u0250\u0250\u2C6F\u2C6F", "\u2C6F", "\u0250\u0250"},
        //empty string tests
        {"Trim", "abba", "", "abba"},
        {"Trim", "", "123", ""},
        {"Trim", "", "", ""},
        {"TrimLeft", "abba", "", "abba"},
        {"TrimLeft", "", "123", ""},
        {"TrimLeft", "", "", ""},
        {"TrimRight", "abba", "", "abba"},
        {"TrimRight", "", "123", ""},
        {"TrimRight", "", "", ""},
        {"TrimRight", "☺\xc0", "☺", "☺\xc0"},
}

func TestTrim(t *testing.T) {
        for _, tc := range trimTests {
                name := tc.f
                var f func([]byte, string) []byte
                switch name {
                case "Trim":
                        f = Trim
                case "TrimLeft":
                        f = TrimLeft
                case "TrimRight":
                        f = TrimRight
                default:
                        t.Errorf("Undefined trim function %s", name)
                }
                actual := string(f([]byte(tc.in), tc.cutset))
                if actual != tc.out {
                        t.Errorf("%s(%q, %q) = %q; want %q", name, tc.in, tc.cutset, actual, tc.out)
                }
        }
}

type predicate struct {
        f    func(r rune) bool
        name string
}

var isSpace = predicate{unicode.IsSpace, "IsSpace"}
var isDigit = predicate{unicode.IsDigit, "IsDigit"}
var isUpper = predicate{unicode.IsUpper, "IsUpper"}
var isValidRune = predicate{
        func(r rune) bool {
                return r != utf8.RuneError
        },
        "IsValidRune",
}

type TrimFuncTest struct {
        f       predicate
        in, out string
}

func not(p predicate) predicate {
        return predicate{
                func(r rune) bool {
                        return !p.f(r)
                },
                "not " + p.name,
        }
}

var trimFuncTests = []TrimFuncTest{
        {isSpace, space + " hello " + space, "hello"},
        {isDigit, "\u0e50\u0e5212hello34\u0e50\u0e51", "hello"},
        {isUpper, "\u2C6F\u2C6F\u2C6F\u2C6FABCDhelloEF\u2C6F\u2C6FGH\u2C6F\u2C6F", "hello"},
        {not(isSpace), "hello" + space + "hello", space},
        {not(isDigit), "hello\u0e50\u0e521234\u0e50\u0e51helo", "\u0e50\u0e521234\u0e50\u0e51"},
        {isValidRune, "ab\xc0a\xc0cd", "\xc0a\xc0"},
        {not(isValidRune), "\xc0a\xc0", "a"},
}

func TestTrimFunc(t *testing.T) {
        for _, tc := range trimFuncTests {
                actual := string(TrimFunc([]byte(tc.in), tc.f.f))
                if actual != tc.out {
                        t.Errorf("TrimFunc(%q, %q) = %q; want %q", tc.in, tc.f.name, actual, tc.out)
                }
        }
}

type IndexFuncTest struct {
        in          string
        f           predicate
        first, last int
}

var indexFuncTests = []IndexFuncTest{
        {"", isValidRune, -1, -1},
        {"abc", isDigit, -1, -1},
        {"0123", isDigit, 0, 3},
        {"a1b", isDigit, 1, 1},
        {space, isSpace, 0, len(space) - 3}, // last rune in space is 3 bytes
        {"\u0e50\u0e5212hello34\u0e50\u0e51", isDigit, 0, 18},
        {"\u2C6F\u2C6F\u2C6F\u2C6FABCDhelloEF\u2C6F\u2C6FGH\u2C6F\u2C6F", isUpper, 0, 34},
        {"12\u0e50\u0e52hello34\u0e50\u0e51", not(isDigit), 8, 12},

        // tests of invalid UTF-8
        {"\x801", isDigit, 1, 1},
        {"\x80abc", isDigit, -1, -1},
        {"\xc0a\xc0", isValidRune, 1, 1},
        {"\xc0a\xc0", not(isValidRune), 0, 2},
        {"\xc0☺\xc0", not(isValidRune), 0, 4},
        {"\xc0☺\xc0\xc0", not(isValidRune), 0, 5},
        {"ab\xc0a\xc0cd", not(isValidRune), 2, 4},
        {"a\xe0\x80cd", not(isValidRune), 1, 2},
}

func TestIndexFunc(t *testing.T) {
        for _, tc := range indexFuncTests {
                first := IndexFunc([]byte(tc.in), tc.f.f)
                if first != tc.first {
                        t.Errorf("IndexFunc(%q, %s) = %d; want %d", tc.in, tc.f.name, first, tc.first)
                }
                last := LastIndexFunc([]byte(tc.in), tc.f.f)
                if last != tc.last {
                        t.Errorf("LastIndexFunc(%q, %s) = %d; want %d", tc.in, tc.f.name, last, tc.last)
                }
        }
}

type ReplaceTest struct {
        in       string
        old, new string
        n        int
        out      string
}

var ReplaceTests = []ReplaceTest{
        {"hello", "l", "L", 0, "hello"},
        {"hello", "l", "L", -1, "heLLo"},
        {"hello", "x", "X", -1, "hello"},
        {"", "x", "X", -1, ""},
        {"radar", "r", "<r>", -1, "<r>ada<r>"},
        {"", "", "<>", -1, "<>"},
        {"banana", "a", "<>", -1, "b<>n<>n<>"},
        {"banana", "a", "<>", 1, "b<>nana"},
        {"banana", "a", "<>", 1000, "b<>n<>n<>"},
        {"banana", "an", "<>", -1, "b<><>a"},
        {"banana", "ana", "<>", -1, "b<>na"},
        {"banana", "", "<>", -1, "<>b<>a<>n<>a<>n<>a<>"},
        {"banana", "", "<>", 10, "<>b<>a<>n<>a<>n<>a<>"},
        {"banana", "", "<>", 6, "<>b<>a<>n<>a<>n<>a"},
        {"banana", "", "<>", 5, "<>b<>a<>n<>a<>na"},
        {"banana", "", "<>", 1, "<>banana"},
        {"banana", "a", "a", -1, "banana"},
        {"banana", "a", "a", 1, "banana"},
        {"☺☻☹", "", "<>", -1, "<>☺<>☻<>☹<>"},
}

func TestReplace(t *testing.T) {
        for _, tt := range ReplaceTests {
                in := append([]byte(tt.in), "<spare>"...)
                in = in[:len(tt.in)]
                out := Replace(in, []byte(tt.old), []byte(tt.new), tt.n)
                if s := string(out); s != tt.out {
                        t.Errorf("Replace(%q, %q, %q, %d) = %q, want %q", tt.in, tt.old, tt.new, tt.n, s, tt.out)
                }
                if cap(in) == cap(out) && &in[:1][0] == &out[:1][0] {
                        t.Errorf("Replace(%q, %q, %q, %d) didn't copy", tt.in, tt.old, tt.new, tt.n)
                }
        }
}

type TitleTest struct {
        in, out string
}

var TitleTests = []TitleTest{
        {"", ""},
        {"a", "A"},
        {" aaa aaa aaa ", " Aaa Aaa Aaa "},
        {" Aaa Aaa Aaa ", " Aaa Aaa Aaa "},
        {"123a456", "123a456"},
        {"double-blind", "Double-Blind"},
        {"ÿøû", "Ÿøû"},
}

func TestTitle(t *testing.T) {
        for _, tt := range TitleTests {
                if s := string(Title([]byte(tt.in))); s != tt.out {
                        t.Errorf("Title(%q) = %q, want %q", tt.in, s, tt.out)
                }
        }
}

var EqualFoldTests = []struct {
        s, t string
        out  bool
}{
        {"abc", "abc", true},
        {"ABcd", "ABcd", true},
        {"123abc", "123ABC", true},
        {"αβδ", "ΑΒΔ", true},
        {"abc", "xyz", false},
        {"abc", "XYZ", false},
        {"abcdefghijk", "abcdefghijX", false},
        {"abcdefghijk", "abcdefghij\u212A", true},
        {"abcdefghijK", "abcdefghij\u212A", true},
        {"abcdefghijkz", "abcdefghij\u212Ay", false},
        {"abcdefghijKz", "abcdefghij\u212Ay", false},
}

func TestEqualFold(t *testing.T) {
        for _, tt := range EqualFoldTests {
                if out := EqualFold([]byte(tt.s), []byte(tt.t)); out != tt.out {
                        t.Errorf("EqualFold(%#q, %#q) = %v, want %v", tt.s, tt.t, out, tt.out)
                }
                if out := EqualFold([]byte(tt.t), []byte(tt.s)); out != tt.out {
                        t.Errorf("EqualFold(%#q, %#q) = %v, want %v", tt.t, tt.s, out, tt.out)
                }
        }
}