length      int
		resExpected string
		errExpected error
	}{
		{"abcd", 1, 1, "a", nil},
		{"abcd", -1, 1, "a", nil},
		{"abcd", 999, 999, "", nil},
		{"", 999, 999, "", nil},
		{"测试abc", 1, 1, "测", nil},
		{"测试abc", 5, 5, "c", nil},
	}

	for i, tc := range evalCases {
		res, err := evalSQLSubstring(tc.s, tc.startIdx, tc.length)
		if res != tc.resExpected || err != tc.errExpected {

	a, b []byte
	i    int
}{
	{[]byte(""), []byte(""), 0},
	{[]byte("a"), []byte(""), 1},
	{[]byte(""), []byte("a"), -1},
	{[]byte("abc"), []byte("abc"), 0},
	{[]byte("abd"), []byte("abc"), 1},
	{[]byte("abc"), []byte("abd"), -1},
	{[]byte("ab"), []byte("abc"), -1},
	{[]byte("abc"), []byte("ab"), 1},
	{[]byte("x"), []byte("ab"), 1},
	{[]byte("ab"), []byte("x"), -1},
	{[]byte("x"), []byte("a"), 1},

		{"/abc/", "/abc"},

		// Remove doubled slash
		{"abc//def//ghi", "abc/def/ghi"},
		{"//abc", "/abc"},
		{"///abc", "/abc"},
		{"//abc//", "/abc"},
		{"abc//", "abc"},

		// Remove . elements
		{"abc/./def", "abc/def"},
		{"/./abc/def", "/abc/def"},
		{"abc/.", "abc"},

		// Remove .. elements
		{"abc/def/ghi/../jkl", "abc/def/jkl"},
		{"abc/def/../ghi/../jkl", "abc/jkl"},
		{"abc/def/..", "abc"},

		},
	}, {
		maker: makeSparse{makeReg{3, "abc"}, sparseHoles{{0, 2}, {5, 2}}, 7},
		tests: []testFnc{
			testRemaining{7, 3},
			testWrite{"\x00\x00abc\x00\x00", 7, nil},
			testRemaining{0, 0},
		},
	}, {
		maker: makeSparse{makeReg{3, "abc"}, sparseHoles{{0, 2}, {5, 2}}, 7},
		tests: []testFnc{
			testRemaining{7, 3},
			testReadFrom{fileOps{int64(2), "abc", int64(1), "\x00"}, 7, nil},
			testRemaining{0, 0},

		}
		err := s.Err()
		if err != nil {
			t.Errorf("#%d: %v", n, err)
		}
	}
}

var wordScanTests = []string{
	"",
	" ",
	"\n",
	"a",
	" a ",
	"abc def",
	" abc def ",
	" abc\tdef\nghi\rjkl\fmno\vpqr\u0085stu\u00a0\n",
}

// Test that the word splitter returns the same data as strings.Fields.
func TestScanWords(t *testing.T) {
	for n, test := range wordScanTests {

	// Write text to the filter one character at a time.
	var out strings.Builder
	f, exitStr := newExitCodeFilter(&out)
	// Embed a "fake" exit code in the middle to check that we don't get caught on it.
	pre := "abc" + exitStr + "123def"
	text := pre + exitStr + `1`
	for i := 0; i < len(text); i++ {
		_, err := f.Write([]byte{text[i]})
		if err != nil {
			t.Fatal(err)
		}
	}

	validCases := []string{
		"a",
		"_a",
		"abc_a",
		"a2",
		`"abc"`,
		`"abc\a""ac"`,
	}
	for i, tc := range validCases {
		err := p.ParseString(tc, &id)
		if err != nil {
			t.Fatalf("%d: %v", i, err)
		}
		// repr.Println(id, repr.Indent("  "), repr.OmitEmpty(true))
	}

	invalidCases := []string{
		"+a",
		"-a",
		"1a",
		`"ab`,
		`abc"`,
		`aa""a`,
		`"a"a"`,
	}

		expected string
	}{
		{bytes.NewBuffer([]byte("")), 0, ""},
		{bytes.NewBuffer([]byte("")), 1, ""},
		{bytes.NewBuffer([]byte("abc")), 0, "abc"},
		{bytes.NewBuffer([]byte("abc")), 1, "bc"},
		{bytes.NewBuffer([]byte("abc")), 2, "c"},
		{bytes.NewBuffer([]byte("abc")), 3, ""},
		{bytes.NewBuffer([]byte("abc")), 4, ""},
	}
	for i, testCase := range testCases {
		r := NewSkipReader(testCase.src, testCase.skipLen)

		{"uint8", uint8(math.MaxUint8), "255"},
		{"uint16", uint16(math.MaxUint16), "65535"},
		{"uint32", uint32(math.MaxUint32), "4294967295"},
		{"uint64", uint64(math.MaxUint64), "18446744073709551615"},
		{"string", "abc", "abc"},
		{"other", true, ""},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			if out := ToString(test.in); test.out != out {

		{
			bucketNames[0], "asia", "asia/europe/", "abc", "", 0,
			ListMultipartsInfo{},
			fmt.Errorf("Invalid combination of uploadID marker '%s' and marker '%s'", "abc", "asia/europe/"), false,
		},
		{
			// Contains a base64 padding character
			bucketNames[0], "asia", "asia/europe", "abc=", "", 0,
			ListMultipartsInfo{},
			fmt.Errorf("Malformed upload id %s", "abc="), false,
		},