src/pkg/strings/strings_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 strings_test

 import (
 	. "strings"
 	"testing"
 	"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
 }

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

 type IndexTest struct {
 	s   string
 	sep string
 	out int
 }

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

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

 // 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 string) int, funcName string, testCases []IndexTest) {
 	for _, test := range testCases {
 		actual := f(test.s, test.sep)
 		if actual != test.out {
 			t.Errorf("%s(%q,%q) = %v; want %v", funcName, test.s, test.sep, actual, test.out)
 		}
 	}
 }

 func TestIndex(t *testing.T) { runIndexTests(t, Index, "Index", indexTests) }

 func TestLastIndex(t *testing.T) { runIndexTests(t, LastIndex, "LastIndex", lastIndexTests) }


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

 var explodetests = []ExplodeTest{
 	ExplodeTest{abcd, 4, []string{"a", "b", "c", "d"}},
 	ExplodeTest{faces, 3, []string{"☺", "☻", "☹"}},
 	ExplodeTest{abcd, 2, []string{"a", "bcd"}},
 }

 func TestExplode(t *testing.T) {
 	for _, tt := range explodetests {
 		a := Split(tt.s, "", tt.n)
 		if !eq(a, tt.a) {
 			t.Errorf("explode(%q, %d) = %v; want %v", tt.s, tt.n, a, tt.a)
 			continue
 		}
 		s := Join(a, "")
 		if s != tt.s {
 			t.Errorf(`Join(explode(%q, %d), "") = %q`, 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, []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(tt.s, tt.sep, tt.n)
 		if !eq(a, tt.a) {
 			t.Errorf("Split(%q, %q, %d) = %v; want %v", tt.s, tt.sep, tt.n, a, tt.a)
 			continue
 		}
 		s := Join(a, tt.sep)
 		if 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(tt.s, tt.sep, tt.n)
 		if !eq(a, tt.a) {
 			t.Errorf(`Split(%q, %q, %d) = %v; want %v`, tt.s, tt.sep, tt.n, a, tt.a)
 			continue
 		}
 		s := Join(a, "")
 		if 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(tt.s)
 		if !eq(a, 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 single string.
 type StringTest struct {
 	in, out string
 }

 // 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(string) string, funcName string, testCases []StringTest) {
 	for _, tc := range testCases {
 		actual := f(tc.in)
 		if actual != tc.out {
 			t.Errorf("%s(%q) = %q; want %q", funcName, tc.in, actual, tc.out)
 		}
 	}
 }

 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
 }

 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, a)
 	expect := tenRunes(unicode.MaxRune)
 	if m != expect {
 		t.Errorf("growing: expected %q got %q", expect, m)
 	}

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

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

 	// 4. Rot13^2
 	m = Map(rot13, Map(rot13, "a to zed"))
 	expect = "a to zed"
 	if 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, "Hello, 세계")
 	expect = "Hello"
 	if 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) }

 func equal(m string, s1, s2 string, t *testing.T) bool {
 	if s1 == s2 {
 		return true
 	}
 	e1 := Split(s1, "", 0)
 	e2 := Split(s2, "", 0)
 	for i, c1 := range e1 {
 		if i > len(e2) {
 			break
 		}
 		r1, _ := utf8.DecodeRuneInString(c1)
 		r2, _ := utf8.DecodeRuneInString(e2[i])
 		if r1 != r2 {
 			t.Errorf("%s diff at %d: U+%04X U+%04X", m, i, r1, r2)
 		}
 	}
 	return false
 }

 func TestCaseConsistency(t *testing.T) {
 	// Make a string of all the runes.
 	a := make([]int, unicode.MaxRune+1)
 	for i := range a {
 		a[i] = i
 	}
 	s := string(a)
 	// convert the cases.
 	upper := ToUpper(s)
 	lower := ToLower(s)

 	// Consistency checks
 	if n := utf8.RuneCountInString(upper); n != unicode.MaxRune+1 {
 		t.Error("rune count wrong in upper:", n)
 	}
 	if n := utf8.RuneCountInString(lower); n != unicode.MaxRune+1 {
 		t.Error("rune count wrong in lower:", n)
 	}
 	if !equal("ToUpper(upper)", ToUpper(upper), upper, t) {
 		t.Error("ToUpper(upper) consistency fail")
 	}
 	if !equal("ToLower(lower)", ToLower(lower), lower, t) {
 		t.Error("ToLower(lower) consistency fail")
 	}
 	/*
 		  These fail because of non-one-to-oneness of the data, such as multiple
 		  upper case 'I' mapping to 'i'.  We comment them out but keep them for
 		  interest.
 		  For instance: CAPITAL LETTER I WITH DOT ABOVE:
 			unicode.ToUpper(unicode.ToLower('\u0130')) != '\u0130'

 		if !equal("ToUpper(lower)", ToUpper(lower), upper, t) {
 			t.Error("ToUpper(lower) consistency fail");
 		}
 		if !equal("ToLower(upper)", ToLower(upper), lower, t) {
 			t.Error("ToLower(upper) consistency fail");
 		}
 	*/
 }

 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 {
 		a := Repeat(tt.in, tt.count)
 		if !equal("Repeat(s)", a, tt.out, t) {
 			t.Errorf("Repeat(%v, %d) = %v; want %v", tt.in, tt.count, a, tt.out)
 			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 {
 		a := Runes(tt.in)
 		if !runesEqual(a, tt.out) {
 			t.Errorf("Runes(%q) = %v; want %v", tt.in, 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", tt.in, s, tt.in)
 			}
 		}
 	}
 }
	// 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 strings_test

	import (
	. "strings"
	"testing"
	"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
	}

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

	type IndexTest struct {
	s string
	sep string
	out int
	}

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

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

	// 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 string) int, funcName string, testCases []IndexTest) {
	for _, test := range testCases {
	actual := f(test.s, test.sep)
	if actual != test.out {
	t.Errorf("%s(%q,%q) = %v; want %v", funcName, test.s, test.sep, actual, test.out)
	}
	}
	}

	func TestIndex(t *testing.T) { runIndexTests(t, Index, "Index", indexTests) }

	func TestLastIndex(t *testing.T) { runIndexTests(t, LastIndex, "LastIndex", lastIndexTests) }


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

	var explodetests = []ExplodeTest{
	ExplodeTest{abcd, 4, []string{"a", "b", "c", "d"}},
	ExplodeTest{faces, 3, []string{"☺", "☻", "☹"}},
	ExplodeTest{abcd, 2, []string{"a", "bcd"}},
	}

	func TestExplode(t *testing.T) {
	for _, tt := range explodetests {
	a := Split(tt.s, "", tt.n)
	if !eq(a, tt.a) {
	t.Errorf("explode(%q, %d) = %v; want %v", tt.s, tt.n, a, tt.a)
	continue
	}
	s := Join(a, "")
	if s != tt.s {
	t.Errorf(`Join(explode(%q, %d), "") = %q`, 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, []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(tt.s, tt.sep, tt.n)
	if !eq(a, tt.a) {
	t.Errorf("Split(%q, %q, %d) = %v; want %v", tt.s, tt.sep, tt.n, a, tt.a)
	continue
	}
	s := Join(a, tt.sep)
	if 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(tt.s, tt.sep, tt.n)
	if !eq(a, tt.a) {
	t.Errorf(`Split(%q, %q, %d) = %v; want %v`, tt.s, tt.sep, tt.n, a, tt.a)
	continue
	}
	s := Join(a, "")
	if 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(tt.s)
	if !eq(a, 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 single string.
	type StringTest struct {
	in, out string
	}

	// 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(string) string, funcName string, testCases []StringTest) {
	for _, tc := range testCases {
	actual := f(tc.in)
	if actual != tc.out {
	t.Errorf("%s(%q) = %q; want %q", funcName, tc.in, actual, tc.out)
	}
	}
	}

	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
	}

	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, a)
	expect := tenRunes(unicode.MaxRune)
	if m != expect {
	t.Errorf("growing: expected %q got %q", expect, m)
	}

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

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

	// 4. Rot13^2
	m = Map(rot13, Map(rot13, "a to zed"))
	expect = "a to zed"
	if 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, "Hello, 세계")
	expect = "Hello"
	if 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) }

	func equal(m string, s1, s2 string, t *testing.T) bool {
	if s1 == s2 {
	return true
	}
	e1 := Split(s1, "", 0)
	e2 := Split(s2, "", 0)
	for i, c1 := range e1 {
	if i > len(e2) {
	break
	}
	r1, _ := utf8.DecodeRuneInString(c1)
	r2, _ := utf8.DecodeRuneInString(e2[i])
	if r1 != r2 {
	t.Errorf("%s diff at %d: U+%04X U+%04X", m, i, r1, r2)
	}
	}
	return false
	}

	func TestCaseConsistency(t *testing.T) {
	// Make a string of all the runes.
	a := make([]int, unicode.MaxRune+1)
	for i := range a {
	a[i] = i
	}
	s := string(a)
	// convert the cases.
	upper := ToUpper(s)
	lower := ToLower(s)

	// Consistency checks
	if n := utf8.RuneCountInString(upper); n != unicode.MaxRune+1 {
	t.Error("rune count wrong in upper:", n)
	}
	if n := utf8.RuneCountInString(lower); n != unicode.MaxRune+1 {
	t.Error("rune count wrong in lower:", n)
	}
	if !equal("ToUpper(upper)", ToUpper(upper), upper, t) {
	t.Error("ToUpper(upper) consistency fail")
	}
	if !equal("ToLower(lower)", ToLower(lower), lower, t) {
	t.Error("ToLower(lower) consistency fail")
	}
	/*
	These fail because of non-one-to-oneness of the data, such as multiple
	upper case 'I' mapping to 'i'. We comment them out but keep them for
	interest.
	For instance: CAPITAL LETTER I WITH DOT ABOVE:
	unicode.ToUpper(unicode.ToLower('\u0130')) != '\u0130'

	if !equal("ToUpper(lower)", ToUpper(lower), upper, t) {
	t.Error("ToUpper(lower) consistency fail");
	}
	if !equal("ToLower(upper)", ToLower(upper), lower, t) {
	t.Error("ToLower(upper) consistency fail");
	}
	*/
	}

	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 {
	a := Repeat(tt.in, tt.count)
	if !equal("Repeat(s)", a, tt.out, t) {
	t.Errorf("Repeat(%v, %d) = %v; want %v", tt.in, tt.count, a, tt.out)
	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 {
	a := Runes(tt.in)
	if !runesEqual(a, tt.out) {
	t.Errorf("Runes(%q) = %v; want %v", tt.in, 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", tt.in, s, tt.in)
	}
	}
	}
	}