prometheus/model/labels/regexp_test.go

// Copyright 2020 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package labels

import (
	"fmt"
	"math/rand"
	"strings"
	"testing"
	"time"
	"unicode/utf8"

	"github.com/grafana/regexp"
	"github.com/grafana/regexp/syntax"
	"github.com/stretchr/testify/require"
)

var (
	asciiRunes = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_")
	regexes    = []string{
		"",
		"foo",
		"^foo",
		"(foo|bar)",
		"foo.*",
		".*foo",
		"^.*foo$",
		"^.+foo$",
		".?",
		".*",
		".+",
		"foo.+",
		".+foo",
		"foo\n.+",
		"foo\n.*",
		".*foo.*",
		".+foo.+",
		"(?s:.*)",
		"(?s:.+)",
		"(?s:^.*foo$)",
		"(?i:foo)",
		"(?i:(foo|bar))",
		"(?i:(foo1|foo2|bar))",
		"^(?i:foo|oo)|(bar)$",
		"(?i:(foo1|foo2|aaa|bbb|ccc|ddd|eee|fff|ggg|hhh|iii|lll|mmm|nnn|ooo|ppp|qqq|rrr|sss|ttt|uuu|vvv|www|xxx|yyy|zzz))",
		"((.*)(bar|b|buzz)(.+)|foo)$",
		"^$",
		"(prometheus|api_prom)_api_v1_.+",
		"10\\.0\\.(1|2)\\.+",
		"10\\.0\\.(1|2).+",
		"((fo(bar))|.+foo)",
		// A long case sensitive alternation.
		"zQPbMkNO|NNSPdvMi|iWuuSoAl|qbvKMimS|IecrXtPa|seTckYqt|NxnyHkgB|fIDlOgKb|UhlWIygH|OtNoJxHG|cUTkFVIV|mTgFIHjr|jQkoIDtE|PPMKxRXl|AwMfwVkQ|CQyMrTQJ|BzrqxVSi|nTpcWuhF|PertdywG|ZZDgCtXN|WWdDPyyE|uVtNQsKk|BdeCHvPZ|wshRnFlH|aOUIitIp|RxZeCdXT|CFZMslCj|AVBZRDxl|IzIGCnhw|ythYuWiz|oztXVXhl|VbLkwqQx|qvaUgyVC|VawUjPWC|ecloYJuj|boCLTdSU|uPrKeAZx|hrMWLWBq|JOnUNHRM|rYnujkPq|dDEdZhIj|DRrfvugG|yEGfDxVV|YMYdJWuP|PHUQZNWM|AmKNrLis|zTxndVfn|FPsHoJnc|EIulZTua|KlAPhdzg|ScHJJCLt|NtTfMzME|eMCwuFdo|SEpJVJbR|cdhXZeCx|sAVtBwRh|kVFEVcMI|jzJrxraA|tGLHTell|NNWoeSaw|DcOKSetX|UXZAJyka|THpMphDP|rizheevl|kDCBRidd|pCZZRqyu|pSygkitl|SwZGkAaW|wILOrfNX|QkwVOerj|kHOMxPDr|EwOVycJv|AJvtzQFS|yEOjKYYB|LizIINLL|JBRSsfcG|YPiUqqNl|IsdEbvee|MjEpGcBm|OxXZVgEQ|xClXGuxa|UzRCGFEb|buJbvfvA|IPZQxRet|oFYShsMc|oBHffuHO|bzzKrcBR|KAjzrGCl|IPUsAVls|OGMUMbIU|gyDccHuR|bjlalnDd|ZLWjeMna|fdsuIlxQ|dVXtiomV|XxedTjNg|XWMHlNoA|nnyqArQX|opfkWGhb|wYtnhdYb",
		// An extremely long case sensitive alternation. This is a special
		// case because the values share common prefixes rather than being
		// entirely random. This is common in the real world. For example, the
		// values of a label like kubernetes pod will often include the
		// deployment name as a prefix.
		"jyyfj00j0061|jyyfj00j0062|jyyfj94j0093|jyyfj99j0093|jyyfm01j0021|jyyfm02j0021|jyefj00j0192|jyefj00j0193|jyefj00j0194|jyefj00j0195|jyefj00j0196|jyefj00j0197|jyefj00j0290|jyefj00j0291|jyefj00j0292|jyefj00j0293|jyefj00j0294|jyefj00j0295|jyefj00j0296|jyefj00j0297|jyefj89j0394|jyefj90j0394|jyefj91j0394|jyefj95j0347|jyefj96j0322|jyefj96j0347|jyefj97j0322|jyefj97j0347|jyefj98j0322|jyefj98j0347|jyefj99j0320|jyefj99j0322|jyefj99j0323|jyefj99j0335|jyefj99j0336|jyefj99j0344|jyefj99j0347|jyefj99j0349|jyefj99j0351|jyeff00j0117|lyyfm01j0025|lyyfm01j0028|lyyfm01j0041|lyyfm01j0133|lyyfm01j0701|lyyfm02j0025|lyyfm02j0028|lyyfm02j0041|lyyfm02j0133|lyyfm02j0701|lyyfm03j0701|lyefj00j0775|lyefj00j0776|lyefj00j0777|lyefj00j0778|lyefj00j0779|lyefj00j0780|lyefj00j0781|lyefj00j0782|lyefj50j3807|lyefj50j3852|lyefj51j3807|lyefj51j3852|lyefj52j3807|lyefj52j3852|lyefj53j3807|lyefj53j3852|lyefj54j3807|lyefj54j3852|lyefj54j3886|lyefj55j3807|lyefj55j3852|lyefj55j3886|lyefj56j3807|lyefj56j3852|lyefj56j3886|lyefj57j3807|lyefj57j3852|lyefj57j3886|lyefj58j3807|lyefj58j3852|lyefj58j3886|lyefj59j3807|lyefj59j3852|lyefj59j3886|lyefj60j3807|lyefj60j3852|lyefj60j3886|lyefj61j3807|lyefj61j3852|lyefj61j3886|lyefj62j3807|lyefj62j3852|lyefj62j3886|lyefj63j3807|lyefj63j3852|lyefj63j3886|lyefj64j3807|lyefj64j3852|lyefj64j3886|lyefj65j3807|lyefj65j3852|lyefj65j3886|lyefj66j3807|lyefj66j3852|lyefj66j3886|lyefj67j3807|lyefj67j3852|lyefj67j3886|lyefj68j3807|lyefj68j3852|lyefj68j3886|lyefj69j3807|lyefj69j3846|lyefj69j3852|lyefj69j3886|lyefj70j3807|lyefj70j3846|lyefj70j3852|lyefj70j3886|lyefj71j3807|lyefj71j3846|lyefj71j3852|lyefj71j3886|lyefj72j3807|lyefj72j3846|lyefj72j3852|lyefj72j3886|lyefj73j3807|lyefj73j3846|lyefj73j3852|lyefj73j3886|lyefj74j3807|lyefj74j3846|lyefj74j3852|lyefj74j3886|lyefj75j3807|lyefj75j3808|lyefj75j3846|lyefj75j3852|lyefj75j3886|lyefj76j3732|lyefj76j3807|lyefj76j3808|lyefj76j3846|lyefj76j3852|lyefj76j3886|lyefj77j3732|lyefj77j3807|lyefj77j3808|lyefj77j3846|lyefj77j3852|lyefj77j3886|lyefj78j3278|lyefj78j3732|lyefj78j3807|lyefj78j3808|lyefj78j3846|lyefj78j3852|lyefj78j3886|lyefj79j3732|lyefj79j3807|lyefj79j3808|lyefj79j3846|lyefj79j3852|lyefj79j3886|lyefj80j3732|lyefj80j3807|lyefj80j3808|lyefj80j3846|lyefj80j3852|lyefj80j3886|lyefj81j3732|lyefj81j3807|lyefj81j3808|lyefj81j3846|lyefj81j3852|lyefj81j3886|lyefj82j3732|lyefj82j3807|lyefj82j3808|lyefj82j3846|lyefj82j3852|lyefj82j3886|lyefj83j3732|lyefj83j3807|lyefj83j3808|lyefj83j3846|lyefj83j3852|lyefj83j3886|lyefj84j3732|lyefj84j3807|lyefj84j3808|lyefj84j3846|lyefj84j3852|lyefj84j3886|lyefj85j3732|lyefj85j3807|lyefj85j3808|lyefj85j3846|lyefj85j3852|lyefj85j3886|lyefj86j3278|lyefj86j3732|lyefj86j3807|lyefj86j3808|lyefj86j3846|lyefj86j3852|lyefj86j3886|lyefj87j3278|lyefj87j3732|lyefj87j3807|lyefj87j3808|lyefj87j3846|lyefj87j3852|lyefj87j3886|lyefj88j3732|lyefj88j3807|lyefj88j3808|lyefj88j3846|lyefj88j3852|lyefj88j3886|lyefj89j3732|lyefj89j3807|lyefj89j3808|lyefj89j3846|lyefj89j3852|lyefj89j3886|lyefj90j3732|lyefj90j3807|lyefj90j3808|lyefj90j3846|lyefj90j3852|lyefj90j3886|lyefj91j3732|lyefj91j3807|lyefj91j3808|lyefj91j3846|lyefj91j3852|lyefj91j3886|lyefj92j3732|lyefj92j3807|lyefj92j3808|lyefj92j3846|lyefj92j3852|lyefj92j3886|lyefj93j3732|lyefj93j3807|lyefj93j3808|lyefj93j3846|lyefj93j3852|lyefj93j3885|lyefj93j3886|lyefj94j3525|lyefj94j3732|lyefj94j3807|lyefj94j3808|lyefj94j3846|lyefj94j3852|lyefj94j3885|lyefj94j3886|lyefj95j3525|lyefj95j3732|lyefj95j3807|lyefj95j3808|lyefj95j3846|lyefj95j3852|lyefj95j3886|lyefj96j3732|lyefj96j3803|lyefj96j3807|lyefj96j3808|lyefj96j3846|lyefj96j3852|lyefj96j3886|lyefj97j3333|lyefj97j3732|lyefj97j3792|lyefj97j3803|lyefj97j3807|lyefj97j3808|lyefj97j3838|lyefj97j3843|lyefj97j3846|lyefj97j3852|lyefj97j3886|lyefj98j3083|lyefj98j3333|lyefj98j3732|lyefj98j3807|lyefj98j3808|lyefj98j3838|lyefj98j3843|lyefj98j3846|lyefj98j3852|lyefj98j3873|lyefj98j3877|lyefj98j3882|lyefj98j3886|lyefj99j2984|lyefj99j3083|lyefj99j3333|lyefj99j3732|lyefj99j3807|lyefj99j3808|lyefj99j3846|lyefj99j3849|lyefj99j3852|lyefj99j3873|lyefj99j3877|lyefj99j3882|lyefj99j3884|lyefj99j3886|lyeff00j0106|lyeff00j01
		// A long case insensitive alternation.
		"(?i:(zQPbMkNO|NNSPdvMi|iWuuSoAl|qbvKMimS|IecrXtPa|seTckYqt|NxnyHkgB|fIDlOgKb|UhlWIygH|OtNoJxHG|cUTkFVIV|mTgFIHjr|jQkoIDtE|PPMKxRXl|AwMfwVkQ|CQyMrTQJ|BzrqxVSi|nTpcWuhF|PertdywG|ZZDgCtXN|WWdDPyyE|uVtNQsKk|BdeCHvPZ|wshRnFlH|aOUIitIp|RxZeCdXT|CFZMslCj|AVBZRDxl|IzIGCnhw|ythYuWiz|oztXVXhl|VbLkwqQx|qvaUgyVC|VawUjPWC|ecloYJuj|boCLTdSU|uPrKeAZx|hrMWLWBq|JOnUNHRM|rYnujkPq|dDEdZhIj|DRrfvugG|yEGfDxVV|YMYdJWuP|PHUQZNWM|AmKNrLis|zTxndVfn|FPsHoJnc|EIulZTua|KlAPhdzg|ScHJJCLt|NtTfMzME|eMCwuFdo|SEpJVJbR|cdhXZeCx|sAVtBwRh|kVFEVcMI|jzJrxraA|tGLHTell|NNWoeSaw|DcOKSetX|UXZAJyka|THpMphDP|rizheevl|kDCBRidd|pCZZRqyu|pSygkitl|SwZGkAaW|wILOrfNX|QkwVOerj|kHOMxPDr|EwOVycJv|AJvtzQFS|yEOjKYYB|LizIINLL|JBRSsfcG|YPiUqqNl|IsdEbvee|MjEpGcBm|OxXZVgEQ|xClXGuxa|UzRCGFEb|buJbvfvA|IPZQxRet|oFYShsMc|oBHffuHO|bzzKrcBR|KAjzrGCl|IPUsAVls|OGMUMbIU|gyDccHuR|bjlalnDd|ZLWjeMna|fdsuIlxQ|dVXtiomV|XxedTjNg|XWMHlNoA|nnyqArQX|opfkWGhb|wYtnhdYb))",
		"(?i:(AAAAAAAAAAAAAAAAAAAAAAAA|BBBBBBBBBBBBBBBBBBBBBBBB|cccccccccccccccccccccccC|ſſſſſſſſſſſſſſſſſſſſſſſſS|SSSSSSSSSSSSSSSSSSSSSSSSſ))",
		// A long case insensitive alternation where each entry ends with ".*".
		"(?i:(zQPbMkNO.*|NNSPdvMi.*|iWuuSoAl.*|qbvKMimS.*|IecrXtPa.*|seTckYqt.*|NxnyHkgB.*|fIDlOgKb.*|UhlWIygH.*|OtNoJxHG.*|cUTkFVIV.*|mTgFIHjr.*|jQkoIDtE.*|PPMKxRXl.*|AwMfwVkQ.*|CQyMrTQJ.*|BzrqxVSi.*|nTpcWuhF.*|PertdywG.*|ZZDgCtXN.*|WWdDPyyE.*|uVtNQsKk.*|BdeCHvPZ.*|wshRnFlH.*|aOUIitIp.*|RxZeCdXT.*|CFZMslCj.*|AVBZRDxl.*|IzIGCnhw.*|ythYuWiz.*|oztXVXhl.*|VbLkwqQx.*|qvaUgyVC.*|VawUjPWC.*|ecloYJuj.*|boCLTdSU.*|uPrKeAZx.*|hrMWLWBq.*|JOnUNHRM.*|rYnujkPq.*|dDEdZhIj.*|DRrfvugG.*|yEGfDxVV.*|YMYdJWuP.*|PHUQZNWM.*|AmKNrLis.*|zTxndVfn.*|FPsHoJnc.*|EIulZTua.*|KlAPhdzg.*|ScHJJCLt.*|NtTfMzME.*|eMCwuFdo.*|SEpJVJbR.*|cdhXZeCx.*|sAVtBwRh.*|kVFEVcMI.*|jzJrxraA.*|tGLHTell.*|NNWoeSaw.*|DcOKSetX.*|UXZAJyka.*|THpMphDP.*|rizheevl.*|kDCBRidd.*|pCZZRqyu.*|pSygkitl.*|SwZGkAaW.*|wILOrfNX.*|QkwVOerj.*|kHOMxPDr.*|EwOVycJv.*|AJvtzQFS.*|yEOjKYYB.*|LizIINLL.*|JBRSsfcG.*|YPiUqqNl.*|IsdEbvee.*|MjEpGcBm.*|OxXZVgEQ.*|xClXGuxa.*|UzRCGFEb.*|buJbvfvA.*|IPZQxRet.*|oFYShsMc.*|oBHffuHO.*|bzzKrcBR.*|KAjzrGCl.*|IPUsAVls.*|OGMUMbIU.*|gyDccHuR.*|bjlalnDd.*|ZLWjeMna.*|fdsuIlxQ.*|dVXtiomV.*|XxedTjNg.*|XWMHlNoA.*|nnyqArQX.*|opfkWGhb.*|wYtnhdYb.*))",
		// A long case insensitive alternation where each entry starts with ".*".
		"(?i:(.*zQPbMkNO|.*NNSPdvMi|.*iWuuSoAl|.*qbvKMimS|.*IecrXtPa|.*seTckYqt|.*NxnyHkgB|.*fIDlOgKb|.*UhlWIygH|.*OtNoJxHG|.*cUTkFVIV|.*mTgFIHjr|.*jQkoIDtE|.*PPMKxRXl|.*AwMfwVkQ|.*CQyMrTQJ|.*BzrqxVSi|.*nTpcWuhF|.*PertdywG|.*ZZDgCtXN|.*WWdDPyyE|.*uVtNQsKk|.*BdeCHvPZ|.*wshRnFlH|.*aOUIitIp|.*RxZeCdXT|.*CFZMslCj|.*AVBZRDxl|.*IzIGCnhw|.*ythYuWiz|.*oztXVXhl|.*VbLkwqQx|.*qvaUgyVC|.*VawUjPWC|.*ecloYJuj|.*boCLTdSU|.*uPrKeAZx|.*hrMWLWBq|.*JOnUNHRM|.*rYnujkPq|.*dDEdZhIj|.*DRrfvugG|.*yEGfDxVV|.*YMYdJWuP|.*PHUQZNWM|.*AmKNrLis|.*zTxndVfn|.*FPsHoJnc|.*EIulZTua|.*KlAPhdzg|.*ScHJJCLt|.*NtTfMzME|.*eMCwuFdo|.*SEpJVJbR|.*cdhXZeCx|.*sAVtBwRh|.*kVFEVcMI|.*jzJrxraA|.*tGLHTell|.*NNWoeSaw|.*DcOKSetX|.*UXZAJyka|.*THpMphDP|.*rizheevl|.*kDCBRidd|.*pCZZRqyu|.*pSygkitl|.*SwZGkAaW|.*wILOrfNX|.*QkwVOerj|.*kHOMxPDr|.*EwOVycJv|.*AJvtzQFS|.*yEOjKYYB|.*LizIINLL|.*JBRSsfcG|.*YPiUqqNl|.*IsdEbvee|.*MjEpGcBm|.*OxXZVgEQ|.*xClXGuxa|.*UzRCGFEb|.*buJbvfvA|.*IPZQxRet|.*oFYShsMc|.*oBHffuHO|.*bzzKrcBR|.*KAjzrGCl|.*IPUsAVls|.*OGMUMbIU|.*gyDccHuR|.*bjlalnDd|.*ZLWjeMna|.*fdsuIlxQ|.*dVXtiomV|.*XxedTjNg|.*XWMHlNoA|.*nnyqArQX|.*opfkWGhb|.*wYtnhdYb))",
		// Quest ".?".
		"fo.?",
		"foo.?",
		"f.?o",
		".*foo.?",
		".?foo.+",
		"foo.?|bar",
		"ſſs",
		// Concat of literals and wildcards.
		".*-.*-.*-.*-.*",
		"(.+)-(.+)-(.+)-(.+)-(.+)",
		"((.*))(?i:f)((.*))o((.*))o((.*))",
		"((.*))f((.*))(?i:o)((.*))o((.*))",
	}
	values = []string{
		"foo", " foo bar", "bar", "buzz\nbar", "bar foo", "bfoo", "\n", "\nfoo", "foo\n", "hello foo world", "hello foo\n world", "",
		"FOO", "Foo", "fOo", "foO", "OO", "Oo", "\nfoo\n", strings.Repeat("f", 20), "prometheus", "prometheus_api_v1", "prometheus_api_v1_foo",
		"10.0.1.20", "10.0.2.10", "10.0.3.30", "10.0.4.40",
		"foofoo0", "foofoo", "😀foo0", "ſſs", "ſſS", "AAAAAAAAAAAAAAAAAAAAAAAA", "BBBBBBBBBBBBBBBBBBBBBBBB", "cccccccccccccccccccccccC", "ſſſſſſſſſſſſſſſſſſſſſſſſS", "SSSSSSSSSSSSSSSSSSSSSSSSſ",

		// Values matching / not matching the test regexps on long alternations.
		"zQPbMkNO", "zQPbMkNo", "jyyfj00j0061", "jyyfj00j006", "jyyfj00j00612", "NNSPdvMi", "NNSPdvMiXXX", "NNSPdvMixxx", "nnSPdvMi", "nnSPdvMiXXX",

		// Invalid utf8
		"\xfefoo",
		"foo\xfe",
		"\xfd",
		"\xff\xff",
	}
)

func TestFastRegexMatcher_MatchString(t *testing.T) {
	// Run the test both against a set of predefined values and a set of random ones.
	testValues := append([]string{}, values...)
	testValues = append(testValues, generateRandomValues()...)

	for _, r := range regexes {
		r := r
		for _, v := range testValues {
			v := v
			t.Run(readable(r)+` on "`+readable(v)+`"`, func(t *testing.T) {
				t.Parallel()
				m, err := NewFastRegexMatcher(r)
				require.NoError(t, err)
				re := regexp.MustCompile("^(?:" + r + ")$")
				require.Equal(t, re.MatchString(v), m.MatchString(v))
			})
		}
	}
}

func readable(s string) string {
	const maxReadableStringLen = 40
	if len(s) < maxReadableStringLen {
		return s
	}
	return s[:maxReadableStringLen] + "..."
}

func TestOptimizeConcatRegex(t *testing.T) {
	cases := []struct {
		regex    string
		prefix   string
		suffix   string
		contains []string
	}{
		{regex: "foo(hello|bar)", prefix: "foo", suffix: "", contains: nil},
		{regex: "foo(hello|bar)world", prefix: "foo", suffix: "world", contains: nil},
		{regex: "foo.*", prefix: "foo", suffix: "", contains: nil},
		{regex: "foo.*hello.*bar", prefix: "foo", suffix: "bar", contains: []string{"hello"}},
		{regex: ".*foo", prefix: "", suffix: "foo", contains: nil},
		{regex: "^.*foo$", prefix: "", suffix: "foo", contains: nil},
		{regex: ".*foo.*", prefix: "", suffix: "", contains: []string{"foo"}},
		{regex: ".*foo.*bar.*", prefix: "", suffix: "", contains: []string{"foo", "bar"}},
		{regex: ".*(foo|bar).*", prefix: "", suffix: "", contains: nil},
		{regex: ".*[abc].*", prefix: "", suffix: "", contains: nil},
		{regex: ".*((?i)abc).*", prefix: "", suffix: "", contains: nil},
		{regex: ".*(?i:abc).*", prefix: "", suffix: "", contains: nil},
		{regex: "(?i:abc).*", prefix: "", suffix: "", contains: nil},
		{regex: ".*(?i:abc)", prefix: "", suffix: "", contains: nil},
		{regex: ".*(?i:abc)def.*", prefix: "", suffix: "", contains: []string{"def"}},
		{regex: "(?i).*(?-i:abc)def", prefix: "", suffix: "", contains: []string{"abc"}},
		{regex: ".*(?msU:abc).*", prefix: "", suffix: "", contains: []string{"abc"}},
		{regex: "[aA]bc.*", prefix: "", suffix: "", contains: []string{"bc"}},
		{regex: "^5..$", prefix: "5", suffix: "", contains: nil},
		{regex: "^release.*", prefix: "release", suffix: "", contains: nil},
		{regex: "^env-[0-9]+laio[1]?[^0-9].*", prefix: "env-", suffix: "", contains: []string{"laio"}},
	}

	for _, c := range cases {
		parsed, err := syntax.Parse(c.regex, syntax.Perl)
		require.NoError(t, err)

		prefix, suffix, contains := optimizeConcatRegex(parsed)
		require.Equal(t, c.prefix, prefix)
		require.Equal(t, c.suffix, suffix)
		require.Equal(t, c.contains, contains)
	}
}

// Refer to https://github.com/prometheus/prometheus/issues/2651.
func TestFindSetMatches(t *testing.T) {
	for _, c := range []struct {
		pattern          string
		expMatches       []string
		expCaseSensitive bool
	}{
		// Single value, coming from a `bar=~"foo"` selector.
		{"foo", []string{"foo"}, true},
		{"^foo", []string{"foo"}, true},
		{"^foo$", []string{"foo"}, true},
		// Simple sets alternates.
		{"foo|bar|zz", []string{"foo", "bar", "zz"}, true},
		// Simple sets alternate and concat (bar|baz is parsed as "ba[rz]").
		{"foo|bar|baz", []string{"foo", "bar", "baz"}, true},
		// Simple sets alternate and concat and capture
		{"foo|bar|baz|(zz)", []string{"foo", "bar", "baz", "zz"}, true},
		// Simple sets alternate and concat and alternates with empty matches
		// parsed as  b(ar|(?:)|uzz) where b(?:) means literal b.
		{"bar|b|buzz", []string{"bar", "b", "buzz"}, true},
		// Skip nested capture groups.
		{"^((bar|b|buzz))$", []string{"bar", "b", "buzz"}, true},
		// Skip outer anchors (it's enforced anyway at the root).
		{"^(bar|b|buzz)$", []string{"bar", "b", "buzz"}, true},
		{"^(?:prod|production)$", []string{"prod", "production"}, true},
		// Do not optimize regexp with inner anchors.
		{"(bar|b|b^uz$z)", nil, false},
		// Do not optimize regexp with empty string matcher.
		{"^$|Running", nil, false},
		// Simple sets containing escaped characters.
		{"fo\\.o|bar\\?|\\^baz", []string{"fo.o", "bar?", "^baz"}, true},
		// using charclass
		{"[abc]d", []string{"ad", "bd", "cd"}, true},
		// high low charset different => A(B[CD]|EF)|BC[XY]
		{"ABC|ABD|AEF|BCX|BCY", []string{"ABC", "ABD", "AEF", "BCX", "BCY"}, true},
		// triple concat
		{"api_(v1|prom)_push", []string{"api_v1_push", "api_prom_push"}, true},
		// triple concat with multiple alternates
		{"(api|rpc)_(v1|prom)_push", []string{"api_v1_push", "api_prom_push", "rpc_v1_push", "rpc_prom_push"}, true},
		{"(api|rpc)_(v1|prom)_(push|query)", []string{"api_v1_push", "api_v1_query", "api_prom_push", "api_prom_query", "rpc_v1_push", "rpc_v1_query", "rpc_prom_push", "rpc_prom_query"}, true},
		// class starting with "-"
		{"[-1-2][a-c]", []string{"-a", "-b", "-c", "1a", "1b", "1c", "2a", "2b", "2c"}, true},
		{"[1^3]", []string{"1", "3", "^"}, true},
		// OpPlus with concat
		{"(.+)/(foo|bar)", nil, false},
		// Simple sets containing special characters without escaping.
		{"fo.o|bar?|^baz", nil, false},
		// case sensitive wrapper.
		{"(?i)foo", []string{"FOO"}, false},
		// case sensitive wrapper on alternate.
		{"(?i)foo|bar|baz", []string{"FOO", "BAR", "BAZ", "BAr", "BAz"}, false},
		// mixed case sensitivity.
		{"(api|rpc)_(v1|prom)_((?i)push|query)", nil, false},
		// mixed case sensitivity concatenation only without capture group.
		{"api_v1_(?i)push", nil, false},
		// mixed case sensitivity alternation only without capture group.
		{"api|(?i)rpc", nil, false},
		// case sensitive after unsetting insensitivity.
		{"rpc|(?i)(?-i)api", []string{"rpc", "api"}, true},
		// case sensitive after unsetting insensitivity in all alternation options.
		{"(?i)((?-i)api|(?-i)rpc)", []string{"api", "rpc"}, true},
		// mixed case sensitivity after unsetting insensitivity.
		{"(?i)rpc|(?-i)api", nil, false},
		// too high charset combination
		{"(api|rpc)_[^0-9]", nil, false},
		// too many combinations
		{"[a-z][a-z]", nil, false},
	} {
		c := c
		t.Run(c.pattern, func(t *testing.T) {
			t.Parallel()
			parsed, err := syntax.Parse(c.pattern, syntax.Perl)
			require.NoError(t, err)
			matches, actualCaseSensitive := findSetMatches(parsed)
			require.Equal(t, c.expMatches, matches)
			require.Equal(t, c.expCaseSensitive, actualCaseSensitive)

			if c.expCaseSensitive {
				// When the regexp is case sensitive, we want to ensure that the
				// set matches are maintained in the final matcher.
				r, err := NewFastRegexMatcher(c.pattern)
				require.NoError(t, err)
				require.Equal(t, c.expMatches, r.SetMatches())
			}
		})
	}
}

func TestFastRegexMatcher_SetMatches_ShouldReturnACopy(t *testing.T) {
	m, err := NewFastRegexMatcher("a|b")
	require.NoError(t, err)
	require.Equal(t, []string{"a", "b"}, m.SetMatches())

	// Manipulate the returned slice.
	matches := m.SetMatches()
	matches[0] = "xxx"
	matches[1] = "yyy"

	// Ensure that if we call SetMatches() again we get the original one.
	require.Equal(t, []string{"a", "b"}, m.SetMatches())
}

func BenchmarkFastRegexMatcher(b *testing.B) {
	texts := generateRandomValues()

	for _, r := range regexes {
		b.Run(getTestNameFromRegexp(r), func(b *testing.B) {
			m, err := NewFastRegexMatcher(r)
			require.NoError(b, err)

			b.ResetTimer()
			for i := 0; i < b.N; i++ {
				for _, text := range texts {
					_ = m.MatchString(text)
				}
			}
		})
	}
}

func BenchmarkToNormalizedLower(b *testing.B) {
	benchCase := func(l int, uppercase string, asciiOnly bool, alt int) string {
		chars := "abcdefghijklmnopqrstuvwxyz"
		if !asciiOnly {
			chars = "aаbбcвdгeдfеgёhжiзjиkйlкmлnмoнpоqпrрsсtтuуvфwхxцyчzш"
		}
		// Swap the alphabet to make alternatives.
		chars = chars[alt%len(chars):] + chars[:alt%len(chars)]

		str := strings.Repeat(chars, l/len(chars)+1)[:l]
		switch uppercase {
		case "first":
			return strings.ToUpper(str[:1]) + str[1:]
		case "last":
			return str[:len(str)-1] + strings.ToUpper(str[len(str)-1:])
		case "all":
			return strings.ToUpper(str)
		case "none":
			return str
		default:
			panic("invalid uppercase")
		}
	}

	for _, l := range []int{10, 100, 1000, 4000} {
		b.Run(fmt.Sprintf("length=%d", l), func(b *testing.B) {
			for _, uppercase := range []string{"none", "first", "last", "all"} {
				b.Run("uppercase="+uppercase, func(b *testing.B) {
					for _, asciiOnly := range []bool{true, false} {
						b.Run(fmt.Sprintf("ascii=%t", asciiOnly), func(b *testing.B) {
							inputs := make([]string, 10)
							for i := range inputs {
								inputs[i] = benchCase(l, uppercase, asciiOnly, i)
							}
							b.ResetTimer()
							for n := 0; n < b.N; n++ {
								toNormalisedLower(inputs[n%len(inputs)])
							}
						})
					}
				})
			}
		})
	}
}

func TestStringMatcherFromRegexp(t *testing.T) {
	for _, c := range []struct {
		pattern string
		exp     StringMatcher
	}{
		{".*", anyStringWithoutNewlineMatcher{}},
		{".*?", anyStringWithoutNewlineMatcher{}},
		{"(?s:.*)", trueMatcher{}},
		{"(.*)", anyStringWithoutNewlineMatcher{}},
		{"^.*$", anyStringWithoutNewlineMatcher{}},
		{".+", &anyNonEmptyStringMatcher{matchNL: false}},
		{"(?s:.+)", &anyNonEmptyStringMatcher{matchNL: true}},
		{"^.+$", &anyNonEmptyStringMatcher{matchNL: false}},
		{"(.+)", &anyNonEmptyStringMatcher{matchNL: false}},
		{"", emptyStringMatcher{}},
		{"^$", emptyStringMatcher{}},
		{"^foo$", &equalStringMatcher{s: "foo", caseSensitive: true}},
		{"^(?i:foo)$", &equalStringMatcher{s: "FOO", caseSensitive: false}},
		{"^((?i:foo)|(bar))$", orStringMatcher([]StringMatcher{&equalStringMatcher{s: "FOO", caseSensitive: false}, &equalStringMatcher{s: "bar", caseSensitive: true}})},
		{`(?i:((foo|bar)))`, orStringMatcher([]StringMatcher{&equalStringMatcher{s: "FOO", caseSensitive: false}, &equalStringMatcher{s: "BAR", caseSensitive: false}})},
		{`(?i:((foo1|foo2|bar)))`, orStringMatcher([]StringMatcher{orStringMatcher([]StringMatcher{&equalStringMatcher{s: "FOO1", caseSensitive: false}, &equalStringMatcher{s: "FOO2", caseSensitive: false}}), &equalStringMatcher{s: "BAR", caseSensitive: false}})},
		{"^((?i:foo|oo)|(bar))$", orStringMatcher([]StringMatcher{&equalStringMatcher{s: "FOO", caseSensitive: false}, &equalStringMatcher{s: "OO", caseSensitive: false}, &equalStringMatcher{s: "bar", caseSensitive: true}})},
		{"(?i:(foo1|foo2|bar))", orStringMatcher([]StringMatcher{orStringMatcher([]StringMatcher{&equalStringMatcher{s: "FOO1", caseSensitive: false}, &equalStringMatcher{s: "FOO2", caseSensitive: false}}), &equalStringMatcher{s: "BAR", caseSensitive: false}})},
		{".*foo.*", &containsStringMatcher{substrings: []string{"foo"}, left: anyStringWithoutNewlineMatcher{}, right: anyStringWithoutNewlineMatcher{}}},
		{"(.*)foo.*", &containsStringMatcher{substrings: []string{"foo"}, left: anyStringWithoutNewlineMatcher{}, right: anyStringWithoutNewlineMatcher{}}},
		{"(.*)foo(.*)", &containsStringMatcher{substrings: []string{"foo"}, left: anyStringWithoutNewlineMatcher{}, right: anyStringWithoutNewlineMatcher{}}},
		{"(.+)foo(.*)", &containsStringMatcher{substrings: []string{"foo"}, left: &anyNonEmptyStringMatcher{matchNL: false}, right: anyStringWithoutNewlineMatcher{}}},
		{"^.+foo.+", &containsStringMatcher{substrings: []string{"foo"}, left: &anyNonEmptyStringMatcher{matchNL: false}, right: &anyNonEmptyStringMatcher{matchNL: false}}},
		{"^(.*)(foo)(.*)$", &containsStringMatcher{substrings: []string{"foo"}, left: anyStringWithoutNewlineMatcher{}, right: anyStringWithoutNewlineMatcher{}}},
		{"^(.*)(foo|foobar)(.*)$", &containsStringMatcher{substrings: []string{"foo", "foobar"}, left: anyStringWithoutNewlineMatcher{}, right: anyStringWithoutNewlineMatcher{}}},
		{"^(.*)(foo|foobar)(.+)$", &containsStringMatcher{substrings: []string{"foo", "foobar"}, left: anyStringWithoutNewlineMatcher{}, right: &anyNonEmptyStringMatcher{matchNL: false}}},
		{"^(.*)(bar|b|buzz)(.+)$", &containsStringMatcher{substrings: []string{"bar", "b", "buzz"}, left: anyStringWithoutNewlineMatcher{}, right: &anyNonEmptyStringMatcher{matchNL: false}}},
		{"10\\.0\\.(1|2)\\.+", nil},
		{"10\\.0\\.(1|2).+", &containsStringMatcher{substrings: []string{"10.0.1", "10.0.2"}, left: nil, right: &anyNonEmptyStringMatcher{matchNL: false}}},
		{"^.+foo", &literalSuffixStringMatcher{left: &anyNonEmptyStringMatcher{}, suffix: "foo", suffixCaseSensitive: true}},
		{"foo-.*$", &literalPrefixSensitiveStringMatcher{prefix: "foo-", right: anyStringWithoutNewlineMatcher{}}},
		{"(prometheus|api_prom)_api_v1_.+", &containsStringMatcher{substrings: []string{"prometheus_api_v1_", "api_prom_api_v1_"}, left: nil, right: &anyNonEmptyStringMatcher{matchNL: false}}},
		{"^((.*)(bar|b|buzz)(.+)|foo)$", orStringMatcher([]StringMatcher{&containsStringMatcher{substrings: []string{"bar", "b", "buzz"}, left: anyStringWithoutNewlineMatcher{}, right: &anyNonEmptyStringMatcher{matchNL: false}}, &equalStringMatcher{s: "foo", caseSensitive: true}})},
		{"((fo(bar))|.+foo)", orStringMatcher([]StringMatcher{orStringMatcher([]StringMatcher{&equalStringMatcher{s: "fobar", caseSensitive: true}}), &literalSuffixStringMatcher{suffix: "foo", suffixCaseSensitive: true, left: &anyNonEmptyStringMatcher{matchNL: false}}})},
		{"(.+)/(gateway|cortex-gw|cortex-gw-internal)", &containsStringMatcher{substrings: []string{"/gateway", "/cortex-gw", "/cortex-gw-internal"}, left: &anyNonEmptyStringMatcher{matchNL: false}, right: nil}},
		// we don't support case insensitive matching for contains.
		// This is because there's no strings.IndexOfFold function.
		// We can revisit later if this is really popular by using strings.ToUpper.
		{"^(.*)((?i)foo|foobar)(.*)$", nil},
		{"(api|rpc)_(v1|prom)_((?i)push|query)", nil},
		{"[a-z][a-z]", nil},
		{"[1^3]", nil},
		{".*foo.*bar.*", nil},
		{`\d*`, nil},
		{".", nil},
		{"/|/bar.*", &literalPrefixSensitiveStringMatcher{prefix: "/", right: orStringMatcher{emptyStringMatcher{}, &literalPrefixSensitiveStringMatcher{prefix: "bar", right: anyStringWithoutNewlineMatcher{}}}}},
		// This one is not supported because  `stringMatcherFromRegexp` is not reentrant for syntax.OpConcat.
		// It would make the code too complex to handle it.
		{"(.+)/(foo.*|bar$)", nil},
		// Case sensitive alternate with same literal prefix and .* suffix.
		{"(xyz-016a-ixb-dp.*|xyz-016a-ixb-op.*)", &literalPrefixSensitiveStringMatcher{prefix: "xyz-016a-ixb-", right: orStringMatcher{&literalPrefixSensitiveStringMatcher{prefix: "dp", right: anyStringWithoutNewlineMatcher{}}, &literalPrefixSensitiveStringMatcher{prefix: "op", right: anyStringWithoutNewlineMatcher{}}}}},
		// Case insensitive alternate with same literal prefix and .* suffix.
		{"(?i:(xyz-016a-ixb-dp.*|xyz-016a-ixb-op.*))", &literalPrefixInsensitiveStringMatcher{prefix: "XYZ-016A-IXB-", right: orStringMatcher{&literalPrefixInsensitiveStringMatcher{prefix: "DP", right: anyStringWithoutNewlineMatcher{}}, &literalPrefixInsensitiveStringMatcher{prefix: "OP", right: anyStringWithoutNewlineMatcher{}}}}},
		{"(?i)(xyz-016a-ixb-dp.*|xyz-016a-ixb-op.*)", &literalPrefixInsensitiveStringMatcher{prefix: "XYZ-016A-IXB-", right: orStringMatcher{&literalPrefixInsensitiveStringMatcher{prefix: "DP", right: anyStringWithoutNewlineMatcher{}}, &literalPrefixInsensitiveStringMatcher{prefix: "OP", right: anyStringWithoutNewlineMatcher{}}}}},
		// Concatenated variable length selectors are not supported.
		{"foo.*.*", nil},
		{"foo.+.+", nil},
		{".*.*foo", nil},
		{".+.+foo", nil},
		{"aaa.?.?", nil},
		{"aaa.?.*", nil},
		// Regexps with ".?".
		{"ext.?|xfs", orStringMatcher{&literalPrefixSensitiveStringMatcher{prefix: "ext", right: &zeroOrOneCharacterStringMatcher{matchNL: false}}, &equalStringMatcher{s: "xfs", caseSensitive: true}}},
		{"(?s)(ext.?|xfs)", orStringMatcher{&literalPrefixSensitiveStringMatcher{prefix: "ext", right: &zeroOrOneCharacterStringMatcher{matchNL: true}}, &equalStringMatcher{s: "xfs", caseSensitive: true}}},
		{"foo.?", &literalPrefixSensitiveStringMatcher{prefix: "foo", right: &zeroOrOneCharacterStringMatcher{matchNL: false}}},
		{"f.?o", nil},
	} {
		c := c
		t.Run(c.pattern, func(t *testing.T) {
			t.Parallel()
			parsed, err := syntax.Parse(c.pattern, syntax.Perl)
			require.NoError(t, err)
			matches := stringMatcherFromRegexp(parsed)
			require.Equal(t, c.exp, matches)
		})
	}
}

func TestStringMatcherFromRegexp_LiteralPrefix(t *testing.T) {
	for _, c := range []struct {
		pattern                       string
		expectedLiteralPrefixMatchers int
		expectedMatches               []string
		expectedNotMatches            []string
	}{
		// Case sensitive.
		{
			pattern:                       "(xyz-016a-ixb-dp.*|xyz-016a-ixb-op.*)",
			expectedLiteralPrefixMatchers: 3,
			expectedMatches:               []string{"xyz-016a-ixb-dp", "xyz-016a-ixb-dpXXX", "xyz-016a-ixb-op", "xyz-016a-ixb-opXXX"},
			expectedNotMatches:            []string{"XYZ-016a-ixb-dp", "xyz-016a-ixb-d", "XYZ-016a-ixb-op", "xyz-016a-ixb-o", "xyz", "dp", "xyz-016a-ixb-dp\n"},
		},

		// Case insensitive.
		{
			pattern:                       "(?i)(xyz-016a-ixb-dp.*|xyz-016a-ixb-op.*)",
			expectedLiteralPrefixMatchers: 3,
			expectedMatches:               []string{"xyz-016a-ixb-dp", "XYZ-016a-ixb-dpXXX", "xyz-016a-ixb-op", "XYZ-016a-ixb-opXXX"},
			expectedNotMatches:            []string{"xyz-016a-ixb-d", "xyz", "dp", "xyz-016a-ixb-dp\n"},
		},

		// Nested literal prefixes, case sensitive.
		{
			pattern:                       "(xyz-(aaa-(111.*)|bbb-(222.*)))|(xyz-(aaa-(333.*)|bbb-(444.*)))",
			expectedLiteralPrefixMatchers: 10,
			expectedMatches:               []string{"xyz-aaa-111", "xyz-aaa-111XXX", "xyz-aaa-333", "xyz-aaa-333XXX", "xyz-bbb-222", "xyz-bbb-222XXX", "xyz-bbb-444", "xyz-bbb-444XXX"},
			expectedNotMatches:            []string{"XYZ-aaa-111", "xyz-aaa-11", "xyz-aaa-222", "xyz-bbb-111"},
		},

		// Nested literal prefixes, case insensitive.
		{
			pattern:                       "(?i)(xyz-(aaa-(111.*)|bbb-(222.*)))|(xyz-(aaa-(333.*)|bbb-(444.*)))",
			expectedLiteralPrefixMatchers: 10,
			expectedMatches:               []string{"xyz-aaa-111", "XYZ-aaa-111XXX", "xyz-aaa-333", "xyz-AAA-333XXX", "xyz-bbb-222", "xyz-BBB-222XXX", "XYZ-bbb-444", "xyz-bbb-444XXX"},
			expectedNotMatches:            []string{"xyz-aaa-11", "xyz-aaa-222", "xyz-bbb-111"},
		},

		// Mixed case sensitivity.
		{
			pattern:                       "(xyz-((?i)(aaa.*|bbb.*)))",
			expectedLiteralPrefixMatchers: 3,
			expectedMatches:               []string{"xyz-aaa", "xyz-AAA", "xyz-aaaXXX", "xyz-AAAXXX", "xyz-bbb", "xyz-BBBXXX"},
			expectedNotMatches:            []string{"XYZ-aaa", "xyz-aa", "yz-aaa", "aaa"},
		},
	} {
		t.Run(c.pattern, func(t *testing.T) {
			parsed, err := syntax.Parse(c.pattern, syntax.Perl)
			require.NoError(t, err)

			matcher := stringMatcherFromRegexp(parsed)
			require.NotNil(t, matcher)

			re := regexp.MustCompile("^" + c.pattern + "$")

			// Pre-condition check: ensure it contains literalPrefixSensitiveStringMatcher or literalPrefixInsensitiveStringMatcher.
			numPrefixMatchers := 0
			visitStringMatcher(matcher, func(matcher StringMatcher) {
				if _, ok := matcher.(*literalPrefixSensitiveStringMatcher); ok {
					numPrefixMatchers++
				}
				if _, ok := matcher.(*literalPrefixInsensitiveStringMatcher); ok {
					numPrefixMatchers++
				}
			})

			require.Equal(t, c.expectedLiteralPrefixMatchers, numPrefixMatchers)

			for _, value := range c.expectedMatches {
				require.Truef(t, matcher.Matches(value), "Value: %s", value)

				// Ensure the golang regexp engine would return the same.
				require.Truef(t, re.MatchString(value), "Value: %s", value)
			}

			for _, value := range c.expectedNotMatches {
				require.Falsef(t, matcher.Matches(value), "Value: %s", value)

				// Ensure the golang regexp engine would return the same.
				require.Falsef(t, re.MatchString(value), "Value: %s", value)
			}
		})
	}
}

func TestStringMatcherFromRegexp_LiteralSuffix(t *testing.T) {
	for _, c := range []struct {
		pattern                       string
		expectedLiteralSuffixMatchers int
		expectedMatches               []string
		expectedNotMatches            []string
	}{
		// Case sensitive.
		{
			pattern:                       "(.*xyz-016a-ixb-dp|.*xyz-016a-ixb-op)",
			expectedLiteralSuffixMatchers: 2,
			expectedMatches:               []string{"xyz-016a-ixb-dp", "XXXxyz-016a-ixb-dp", "xyz-016a-ixb-op", "XXXxyz-016a-ixb-op"},
			expectedNotMatches:            []string{"XYZ-016a-ixb-dp", "yz-016a-ixb-dp", "XYZ-016a-ixb-op", "xyz-016a-ixb-o", "xyz", "dp", "\nxyz-016a-ixb-dp"},
		},

		// Case insensitive.
		{
			pattern:                       "(?i)(.*xyz-016a-ixb-dp|.*xyz-016a-ixb-op)",
			expectedLiteralSuffixMatchers: 2,
			expectedMatches:               []string{"xyz-016a-ixb-dp", "XYZ-016a-ixb-dp", "XXXxyz-016a-ixb-dp", "XyZ-016a-ixb-op", "XXXxyz-016a-ixb-op"},
			expectedNotMatches:            []string{"yz-016a-ixb-dp", "xyz-016a-ixb-o", "xyz", "dp", "\nxyz-016a-ixb-dp"},
		},

		// Nested literal suffixes, case sensitive.
		{
			pattern:                       "(.*aaa|.*bbb(.*ccc|.*ddd))",
			expectedLiteralSuffixMatchers: 3,
			expectedMatches:               []string{"aaa", "XXXaaa", "bbbccc", "XXXbbbccc", "XXXbbbXXXccc", "bbbddd", "bbbddd", "XXXbbbddd", "XXXbbbXXXddd", "bbbXXXccc", "aaabbbccc", "aaabbbddd"},
			expectedNotMatches:            []string{"AAA", "aa", "Xaa", "BBBCCC", "bb", "Xbb", "bbccc", "bbbcc", "bbbdd"},
		},

		// Mixed case sensitivity.
		{
			pattern:                       "(.*aaa|.*bbb((?i)(.*ccc|.*ddd)))",
			expectedLiteralSuffixMatchers: 3,
			expectedMatches:               []string{"aaa", "XXXaaa", "bbbccc", "bbbCCC", "bbbXXXCCC", "bbbddd", "bbbDDD", "bbbXXXddd", "bbbXXXDDD"},
			expectedNotMatches:            []string{"AAA", "XXXAAA", "BBBccc", "BBBCCC", "aaaBBB"},
		},
	} {
		t.Run(c.pattern, func(t *testing.T) {
			parsed, err := syntax.Parse(c.pattern, syntax.Perl)
			require.NoError(t, err)

			matcher := stringMatcherFromRegexp(parsed)
			require.NotNil(t, matcher)

			re := regexp.MustCompile("^" + c.pattern + "$")

			// Pre-condition check: ensure it contains literalSuffixStringMatcher.
			numSuffixMatchers := 0
			visitStringMatcher(matcher, func(matcher StringMatcher) {
				if _, ok := matcher.(*literalSuffixStringMatcher); ok {
					numSuffixMatchers++
				}
			})

			require.Equal(t, c.expectedLiteralSuffixMatchers, numSuffixMatchers)

			for _, value := range c.expectedMatches {
				require.Truef(t, matcher.Matches(value), "Value: %s", value)

				// Ensure the golang regexp engine would return the same.
				require.Truef(t, re.MatchString(value), "Value: %s", value)
			}

			for _, value := range c.expectedNotMatches {
				require.Falsef(t, matcher.Matches(value), "Value: %s", value)

				// Ensure the golang regexp engine would return the same.
				require.Falsef(t, re.MatchString(value), "Value: %s", value)
			}
		})
	}
}

func TestStringMatcherFromRegexp_Quest(t *testing.T) {
	for _, c := range []struct {
		pattern                   string
		expectedZeroOrOneMatchers int
		expectedMatches           []string
		expectedNotMatches        []string
	}{
		// Not match newline.
		{
			pattern:                   "test.?",
			expectedZeroOrOneMatchers: 1,
			expectedMatches:           []string{"test", "test!"},
			expectedNotMatches:        []string{"test\n", "tes", "test!!"},
		},
		{
			pattern:                   ".?test",
			expectedZeroOrOneMatchers: 1,
			expectedMatches:           []string{"test", "!test"},
			expectedNotMatches:        []string{"\ntest", "tes", "test!"},
		},
		{
			pattern:                   "(aaa.?|bbb.?)",
			expectedZeroOrOneMatchers: 2,
			expectedMatches:           []string{"aaa", "aaaX", "bbb", "bbbX"},
			expectedNotMatches:        []string{"aa", "aaaXX", "aaa\n", "bb", "bbbXX", "bbb\n"},
		},
		{
			pattern:                   ".*aaa.?",
			expectedZeroOrOneMatchers: 1,
			expectedMatches:           []string{"aaa", "Xaaa", "aaaX", "XXXaaa", "XXXaaaX"},
			expectedNotMatches:        []string{"aa", "aaaXX", "XXXaaaXXX", "XXXaaa\n"},
		},

		// Match newline.
		{
			pattern:                   "(?s)test.?",
			expectedZeroOrOneMatchers: 1,
			expectedMatches:           []string{"test", "test!", "test\n"},
			expectedNotMatches:        []string{"tes", "test!!", "test\n\n"},
		},

		// Mixed flags (a part matches newline another doesn't).
		{
			pattern:                   "(aaa.?|((?s).?bbb.+))",
			expectedZeroOrOneMatchers: 2,
			expectedMatches:           []string{"aaa", "aaaX", "bbbX", "XbbbX", "bbbXXX", "\nbbbX"},
			expectedNotMatches:        []string{"aa", "aaa\n", "Xbbb", "\nbbb"},
		},
	} {
		t.Run(c.pattern, func(t *testing.T) {
			parsed, err := syntax.Parse(c.pattern, syntax.Perl)
			require.NoError(t, err)

			matcher := stringMatcherFromRegexp(parsed)
			require.NotNil(t, matcher)

			re := regexp.MustCompile("^" + c.pattern + "$")

			// Pre-condition check: ensure it contains zeroOrOneCharacterStringMatcher.
			numZeroOrOneMatchers := 0
			visitStringMatcher(matcher, func(matcher StringMatcher) {
				if _, ok := matcher.(*zeroOrOneCharacterStringMatcher); ok {
					numZeroOrOneMatchers++
				}
			})

			require.Equal(t, c.expectedZeroOrOneMatchers, numZeroOrOneMatchers)

			for _, value := range c.expectedMatches {
				require.Truef(t, matcher.Matches(value), "Value: %s", value)

				// Ensure the golang regexp engine would return the same.
				require.Truef(t, re.MatchString(value), "Value: %s", value)
			}

			for _, value := range c.expectedNotMatches {
				require.Falsef(t, matcher.Matches(value), "Value: %s", value)

				// Ensure the golang regexp engine would return the same.
				require.Falsef(t, re.MatchString(value), "Value: %s", value)
			}
		})
	}
}

func randString(randGenerator *rand.Rand, length int) string {
	b := make([]rune, length)
	for i := range b {
		b[i] = asciiRunes[randGenerator.Intn(len(asciiRunes))]
	}
	return string(b)
}

func randStrings(randGenerator *rand.Rand, many, length int) []string {
	out := make([]string, 0, many)
	for i := 0; i < many; i++ {
		out = append(out, randString(randGenerator, length))
	}
	return out
}

func TestOptimizeEqualStringMatchers(t *testing.T) {
	tests := map[string]struct {
		input                 StringMatcher
		expectedValues        []string
		expectedCaseSensitive bool
	}{
		"should skip optimization on orStringMatcher with containsStringMatcher": {
			input: orStringMatcher{
				&equalStringMatcher{s: "FOO", caseSensitive: true},
				&containsStringMatcher{substrings: []string{"a", "b", "c"}},
			},
			expectedValues: nil,
		},
		"should run optimization on orStringMatcher with equalStringMatcher and same case sensitivity": {
			input: orStringMatcher{
				&equalStringMatcher{s: "FOO", caseSensitive: true},
				&equalStringMatcher{s: "bar", caseSensitive: true},
				&equalStringMatcher{s: "baz", caseSensitive: true},
			},
			expectedValues:        []string{"FOO", "bar", "baz"},
			expectedCaseSensitive: true,
		},
		"should skip optimization on orStringMatcher with equalStringMatcher but different case sensitivity": {
			input: orStringMatcher{
				&equalStringMatcher{s: "FOO", caseSensitive: true},
				&equalStringMatcher{s: "bar", caseSensitive: false},
				&equalStringMatcher{s: "baz", caseSensitive: true},
			},
			expectedValues: nil,
		},
		"should run optimization on orStringMatcher with nested orStringMatcher and equalStringMatcher, and same case sensitivity": {
			input: orStringMatcher{
				&equalStringMatcher{s: "FOO", caseSensitive: true},
				orStringMatcher{
					&equalStringMatcher{s: "bar", caseSensitive: true},
					&equalStringMatcher{s: "xxx", caseSensitive: true},
				},
				&equalStringMatcher{s: "baz", caseSensitive: true},
			},
			expectedValues:        []string{"FOO", "bar", "xxx", "baz"},
			expectedCaseSensitive: true,
		},
		"should skip optimization on orStringMatcher with nested orStringMatcher and equalStringMatcher, but different case sensitivity": {
			input: orStringMatcher{
				&equalStringMatcher{s: "FOO", caseSensitive: true},
				orStringMatcher{
					// Case sensitivity is different within items at the same level.
					&equalStringMatcher{s: "bar", caseSensitive: true},
					&equalStringMatcher{s: "xxx", caseSensitive: false},
				},
				&equalStringMatcher{s: "baz", caseSensitive: true},
			},
			expectedValues: nil,
		},
		"should skip optimization on orStringMatcher with nested orStringMatcher and equalStringMatcher, but different case sensitivity in the nested one": {
			input: orStringMatcher{
				&equalStringMatcher{s: "FOO", caseSensitive: true},
				// Case sensitivity is different between the parent and child.
				orStringMatcher{
					&equalStringMatcher{s: "bar", caseSensitive: false},
					&equalStringMatcher{s: "xxx", caseSensitive: false},
				},
				&equalStringMatcher{s: "baz", caseSensitive: true},
			},
			expectedValues: nil,
		},
		"should return unchanged values on few case insensitive matchers": {
			input: orStringMatcher{
				&equalStringMatcher{s: "FOO", caseSensitive: false},
				orStringMatcher{
					&equalStringMatcher{s: "bAr", caseSensitive: false},
				},
				&equalStringMatcher{s: "baZ", caseSensitive: false},
			},
			expectedValues:        []string{"FOO", "bAr", "baZ"},
			expectedCaseSensitive: false,
		},
	}

	for testName, testData := range tests {
		t.Run(testName, func(t *testing.T) {
			actualMatcher := optimizeEqualStringMatchers(testData.input, 0)

			if testData.expectedValues == nil {
				require.IsType(t, testData.input, actualMatcher)
			} else {
				require.IsType(t, &equalMultiStringSliceMatcher{}, actualMatcher)
				require.Equal(t, testData.expectedValues, actualMatcher.(*equalMultiStringSliceMatcher).values)
				require.Equal(t, testData.expectedCaseSensitive, actualMatcher.(*equalMultiStringSliceMatcher).caseSensitive)
			}
		})
	}
}

func TestNewEqualMultiStringMatcher(t *testing.T) {
	tests := map[string]struct {
		values             []string
		caseSensitive      bool
		expectedValuesMap  map[string]struct{}
		expectedValuesList []string
	}{
		"few case sensitive values": {
			values:             []string{"a", "B"},
			caseSensitive:      true,
			expectedValuesList: []string{"a", "B"},
		},
		"few case insensitive values": {
			values:             []string{"a", "B"},
			caseSensitive:      false,
			expectedValuesList: []string{"a", "B"},
		},
		"many case sensitive values": {
			values:            []string{"a", "B", "c", "D", "e", "F", "g", "H", "i", "L", "m", "N", "o", "P", "q", "r"},
			caseSensitive:     true,
			expectedValuesMap: map[string]struct{}{"a": {}, "B": {}, "c": {}, "D": {}, "e": {}, "F": {}, "g": {}, "H": {}, "i": {}, "L": {}, "m": {}, "N": {}, "o": {}, "P": {}, "q": {}, "r": {}},
		},
		"many case insensitive values": {
			values:            []string{"a", "B", "c", "D", "e", "F", "g", "H", "i", "L", "m", "N", "o", "P", "q", "r"},
			caseSensitive:     false,
			expectedValuesMap: map[string]struct{}{"a": {}, "b": {}, "c": {}, "d": {}, "e": {}, "f": {}, "g": {}, "h": {}, "i": {}, "l": {}, "m": {}, "n": {}, "o": {}, "p": {}, "q": {}, "r": {}},
		},
	}

	for testName, testData := range tests {
		t.Run(testName, func(t *testing.T) {
			matcher := newEqualMultiStringMatcher(testData.caseSensitive, len(testData.values))
			for _, v := range testData.values {
				matcher.add(v)
			}
			if testData.expectedValuesMap != nil {
				require.IsType(t, &equalMultiStringMapMatcher{}, matcher)
				require.Equal(t, testData.expectedValuesMap, matcher.(*equalMultiStringMapMatcher).values)
				require.Equal(t, testData.caseSensitive, matcher.(*equalMultiStringMapMatcher).caseSensitive)
			}
			if testData.expectedValuesList != nil {
				require.IsType(t, &equalMultiStringSliceMatcher{}, matcher)
				require.Equal(t, testData.expectedValuesList, matcher.(*equalMultiStringSliceMatcher).values)
				require.Equal(t, testData.caseSensitive, matcher.(*equalMultiStringSliceMatcher).caseSensitive)
			}
		})
	}
}

func TestEqualMultiStringMatcher_Matches(t *testing.T) {
	tests := map[string]struct {
		values             []string
		caseSensitive      bool
		expectedMatches    []string
		expectedNotMatches []string
	}{
		"few case sensitive values": {
			values:             []string{"a", "B"},
			caseSensitive:      true,
			expectedMatches:    []string{"a", "B"},
			expectedNotMatches: []string{"A", "b"},
		},
		"few case insensitive values": {
			values:             []string{"a", "B"},
			caseSensitive:      false,
			expectedMatches:    []string{"a", "A", "b", "B"},
			expectedNotMatches: []string{"c", "C"},
		},
		"many case sensitive values": {
			values:             []string{"a", "B", "c", "D", "e", "F", "g", "H", "i", "L", "m", "N", "o", "P", "q", "r"},
			caseSensitive:      true,
			expectedMatches:    []string{"a", "B"},
			expectedNotMatches: []string{"A", "b"},
		},
		"many case insensitive values": {
			values:             []string{"a", "B", "c", "D", "e", "F", "g", "H", "i", "L", "m", "N", "o", "P", "q", "r"},
			caseSensitive:      false,
			expectedMatches:    []string{"a", "A", "b", "B"},
			expectedNotMatches: []string{"x", "X"},
		},
	}

	for testName, testData := range tests {
		t.Run(testName, func(t *testing.T) {
			matcher := newEqualMultiStringMatcher(testData.caseSensitive, len(testData.values))
			for _, v := range testData.values {
				matcher.add(v)
			}

			for _, v := range testData.expectedMatches {
				require.True(t, matcher.Matches(v), "value: %s", v)
			}
			for _, v := range testData.expectedNotMatches {
				require.False(t, matcher.Matches(v), "value: %s", v)
			}
		})
	}
}

func TestFindEqualStringMatchers(t *testing.T) {
	type match struct {
		s             string
		caseSensitive bool
	}

	// Utility to call findEqualStringMatchers() and collect all callback invocations.
	findEqualStringMatchersAndCollectMatches := func(input StringMatcher) (matches []match, ok bool) {
		ok = findEqualStringMatchers(input, func(matcher *equalStringMatcher) bool {
			matches = append(matches, match{matcher.s, matcher.caseSensitive})
			return true
		})
		return
	}

	t.Run("empty matcher", func(t *testing.T) {
		actualMatches, actualOk := findEqualStringMatchersAndCollectMatches(emptyStringMatcher{})
		require.False(t, actualOk)
		require.Empty(t, actualMatches)
	})

	t.Run("concat of literal matchers (case sensitive)", func(t *testing.T) {
		actualMatches, actualOk := findEqualStringMatchersAndCollectMatches(
			orStringMatcher{
				&equalStringMatcher{s: "test-1", caseSensitive: true},
				&equalStringMatcher{s: "test-2", caseSensitive: true},
			},
		)

		require.True(t, actualOk)
		require.Equal(t, []match{{"test-1", true}, {"test-2", true}}, actualMatches)
	})

	t.Run("concat of literal matchers (case insensitive)", func(t *testing.T) {
		actualMatches, actualOk := findEqualStringMatchersAndCollectMatches(
			orStringMatcher{
				&equalStringMatcher{s: "test-1", caseSensitive: false},
				&equalStringMatcher{s: "test-2", caseSensitive: false},
			},
		)

		require.True(t, actualOk)
		require.Equal(t, []match{{"test-1", false}, {"test-2", false}}, actualMatches)
	})

	t.Run("concat of literal matchers (mixed case)", func(t *testing.T) {
		actualMatches, actualOk := findEqualStringMatchersAndCollectMatches(
			orStringMatcher{
				&equalStringMatcher{s: "test-1", caseSensitive: false},
				&equalStringMatcher{s: "test-2", caseSensitive: true},
			},
		)

		require.True(t, actualOk)
		require.Equal(t, []match{{"test-1", false}, {"test-2", true}}, actualMatches)
	})
}

// This benchmark is used to find a good threshold to use to apply the optimization
// done by optimizeEqualStringMatchers().
func BenchmarkOptimizeEqualStringMatchers(b *testing.B) {
	randGenerator := rand.New(rand.NewSource(time.Now().UnixNano()))

	// Generate variable lengths random texts to match against.
	texts := append([]string{}, randStrings(randGenerator, 10, 10)...)
	texts = append(texts, randStrings(randGenerator, 5, 30)...)
	texts = append(texts, randStrings(randGenerator, 1, 100)...)

	for numAlternations := 2; numAlternations <= 256; numAlternations *= 2 {
		for _, caseSensitive := range []bool{true, false} {
			b.Run(fmt.Sprintf("alternations: %d case sensitive: %t", numAlternations, caseSensitive), func(b *testing.B) {
				// Generate a regex with the expected number of alternations.
				re := strings.Join(randStrings(randGenerator, numAlternations, 10), "|")
				if !caseSensitive {
					re = "(?i:(" + re + "))"
				}

				parsed, err := syntax.Parse(re, syntax.Perl)
				require.NoError(b, err)

				unoptimized := stringMatcherFromRegexpInternal(parsed)
				require.IsType(b, orStringMatcher{}, unoptimized)

				optimized := optimizeEqualStringMatchers(unoptimized, 0)
				if numAlternations < minEqualMultiStringMatcherMapThreshold {
					require.IsType(b, &equalMultiStringSliceMatcher{}, optimized)
				} else {
					require.IsType(b, &equalMultiStringMapMatcher{}, optimized)
				}

				b.Run("without optimizeEqualStringMatchers()", func(b *testing.B) {
					for n := 0; n < b.N; n++ {
						for _, t := range texts {
							unoptimized.Matches(t)
						}
					}
				})

				b.Run("with optimizeEqualStringMatchers()", func(b *testing.B) {
					for n := 0; n < b.N; n++ {
						for _, t := range texts {
							optimized.Matches(t)
						}
					}
				})
			})
		}
	}
}

func TestZeroOrOneCharacterStringMatcher(t *testing.T) {
	t.Run("match newline", func(t *testing.T) {
		matcher := &zeroOrOneCharacterStringMatcher{matchNL: true}
		require.True(t, matcher.Matches(""))
		require.True(t, matcher.Matches("x"))
		require.True(t, matcher.Matches("\n"))
		require.False(t, matcher.Matches("xx"))
		require.False(t, matcher.Matches("\n\n"))
	})

	t.Run("do not match newline", func(t *testing.T) {
		matcher := &zeroOrOneCharacterStringMatcher{matchNL: false}
		require.True(t, matcher.Matches(""))
		require.True(t, matcher.Matches("x"))
		require.False(t, matcher.Matches("\n"))
		require.False(t, matcher.Matches("xx"))
		require.False(t, matcher.Matches("\n\n"))
	})

	t.Run("unicode", func(t *testing.T) {
		// Just for documentation purposes, emoji1 is 1 rune, emoji2 is 2 runes.
		// Having this in mind, will make future readers fixing tests easier.
		emoji1 := "😀"
		emoji2 := "❤️"
		require.Equal(t, 1, utf8.RuneCountInString(emoji1))
		require.Equal(t, 2, utf8.RuneCountInString(emoji2))

		matcher := &zeroOrOneCharacterStringMatcher{matchNL: true}
		require.True(t, matcher.Matches(emoji1))
		require.False(t, matcher.Matches(emoji2))
		require.False(t, matcher.Matches(emoji1+emoji1))
		require.False(t, matcher.Matches("x"+emoji1))
		require.False(t, matcher.Matches(emoji1+"x"))
		require.False(t, matcher.Matches(emoji1+emoji2))
	})

	t.Run("invalid unicode", func(t *testing.T) {
		// Just for reference, we also compare to what `^.?$` regular expression matches.
		re := regexp.MustCompile("^.?$")
		matcher := &zeroOrOneCharacterStringMatcher{matchNL: true}

		requireMatches := func(s string, expected bool) {
			t.Helper()
			require.Equal(t, expected, matcher.Matches(s))
			require.Equal(t, re.MatchString(s), matcher.Matches(s))
		}

		requireMatches("\xff", true)
		requireMatches("x\xff", false)
		requireMatches("\xffx", false)
		requireMatches("\xff\xfe", false)
	})
}

func BenchmarkZeroOrOneCharacterStringMatcher(b *testing.B) {
	type benchCase struct {
		str     string
		matches bool
	}

	emoji1 := "😀"
	emoji2 := "❤️"
	cases := []benchCase{
		{"", true},
		{"x", true},
		{"\n", true},
		{"xx", false},
		{"\n\n", false},
		{emoji1, true},
		{emoji2, false},
		{emoji1 + emoji1, false},
		{strings.Repeat("x", 100), false},
		{strings.Repeat(emoji1, 100), false},
		{strings.Repeat(emoji2, 100), false},
	}

	matcher := &zeroOrOneCharacterStringMatcher{matchNL: true}
	b.ResetTimer()

	for n := 0; n < b.N; n++ {
		c := cases[n%len(cases)]
		got := matcher.Matches(c.str)
		if got != c.matches {
			b.Fatalf("unexpected result for %q: got %t, want %t", c.str, got, c.matches)
		}
	}
}

func TestLiteralPrefixSensitiveStringMatcher(t *testing.T) {
	m := &literalPrefixSensitiveStringMatcher{prefix: "mar", right: &emptyStringMatcher{}}
	require.True(t, m.Matches("mar"))
	require.False(t, m.Matches("marco"))
	require.False(t, m.Matches("ma"))
	require.False(t, m.Matches("mAr"))

	m = &literalPrefixSensitiveStringMatcher{prefix: "mar", right: &equalStringMatcher{s: "co", caseSensitive: false}}
	require.True(t, m.Matches("marco"))
	require.True(t, m.Matches("marCO"))
	require.False(t, m.Matches("MARco"))
	require.False(t, m.Matches("mar"))
	require.False(t, m.Matches("marcopracucci"))
}

func TestLiteralPrefixInsensitiveStringMatcher(t *testing.T) {
	m := &literalPrefixInsensitiveStringMatcher{prefix: "mar", right: &emptyStringMatcher{}}
	require.True(t, m.Matches("mar"))
	require.False(t, m.Matches("marco"))
	require.False(t, m.Matches("ma"))
	require.True(t, m.Matches("mAr"))
}

func TestLiteralSuffixStringMatcher(t *testing.T) {
	m := &literalSuffixStringMatcher{left: &emptyStringMatcher{}, suffix: "co", suffixCaseSensitive: true}
	require.True(t, m.Matches("co"))
	require.False(t, m.Matches("marco"))
	require.False(t, m.Matches("coo"))
	require.False(t, m.Matches("Co"))

	m = &literalSuffixStringMatcher{left: &emptyStringMatcher{}, suffix: "co", suffixCaseSensitive: false}
	require.True(t, m.Matches("co"))
	require.False(t, m.Matches("marco"))
	require.False(t, m.Matches("coo"))
	require.True(t, m.Matches("Co"))

	m = &literalSuffixStringMatcher{left: &equalStringMatcher{s: "mar", caseSensitive: false}, suffix: "co", suffixCaseSensitive: true}
	require.True(t, m.Matches("marco"))
	require.True(t, m.Matches("MARco"))
	require.False(t, m.Matches("marCO"))
	require.False(t, m.Matches("mar"))
	require.False(t, m.Matches("marcopracucci"))

	m = &literalSuffixStringMatcher{left: &equalStringMatcher{s: "mar", caseSensitive: false}, suffix: "co", suffixCaseSensitive: false}
	require.True(t, m.Matches("marco"))
	require.True(t, m.Matches("MARco"))
	require.True(t, m.Matches("marCO"))
	require.False(t, m.Matches("mar"))
	require.False(t, m.Matches("marcopracucci"))
}

func TestHasPrefixCaseInsensitive(t *testing.T) {
	require.True(t, hasPrefixCaseInsensitive("marco", "mar"))
	require.True(t, hasPrefixCaseInsensitive("mArco", "mar"))
	require.True(t, hasPrefixCaseInsensitive("marco", "MaR"))
	require.True(t, hasPrefixCaseInsensitive("marco", "marco"))
	require.True(t, hasPrefixCaseInsensitive("mArco", "marco"))

	require.False(t, hasPrefixCaseInsensitive("marco", "a"))
	require.False(t, hasPrefixCaseInsensitive("marco", "abcdefghi"))
}

func TestHasSuffixCaseInsensitive(t *testing.T) {
	require.True(t, hasSuffixCaseInsensitive("marco", "rco"))
	require.True(t, hasSuffixCaseInsensitive("marco", "RcO"))
	require.True(t, hasSuffixCaseInsensitive("marco", "marco"))
	require.False(t, hasSuffixCaseInsensitive("marco", "a"))
	require.False(t, hasSuffixCaseInsensitive("marco", "abcdefghi"))
}

func TestContainsInOrder(t *testing.T) {
	require.True(t, containsInOrder("abcdefghilmno", []string{"ab", "cd", "no"}))
	require.True(t, containsInOrder("abcdefghilmno", []string{"def", "hil"}))

	require.False(t, containsInOrder("abcdefghilmno", []string{"ac"}))
	require.False(t, containsInOrder("abcdefghilmno", []string{"ab", "cd", "de"}))
	require.False(t, containsInOrder("abcdefghilmno", []string{"cd", "ab"}))
}

func getTestNameFromRegexp(re string) string {
	if len(re) > 32 {
		return re[:32]
	}
	return re
}

func generateRandomValues() []string {
	// Init the random seed with a constant, so that it doesn't change between runs.
	randGenerator := rand.New(rand.NewSource(1))

	// Generate variable lengths random texts to match against.
	texts := append([]string{}, randStrings(randGenerator, 10, 10)...)
	texts = append(texts, randStrings(randGenerator, 5, 30)...)
	texts = append(texts, randStrings(randGenerator, 1, 100)...)
	texts = append(texts, "foo"+randString(randGenerator, 50))
	texts = append(texts, randString(randGenerator, 50)+"foo")

	return texts
}

func visitStringMatcher(matcher StringMatcher, callback func(matcher StringMatcher)) {
	callback(matcher)

	switch casted := matcher.(type) {
	case *containsStringMatcher:
		if casted.left != nil {
			visitStringMatcher(casted.left, callback)
		}
		if casted.right != nil {
			visitStringMatcher(casted.right, callback)
		}

	case *literalPrefixSensitiveStringMatcher:
		visitStringMatcher(casted.right, callback)

	case *literalPrefixInsensitiveStringMatcher:
		visitStringMatcher(casted.right, callback)

	case *literalSuffixStringMatcher:
		visitStringMatcher(casted.left, callback)

	case orStringMatcher:
		for _, entry := range casted {
			visitStringMatcher(entry, callback)
		}

	// No nested matchers for the following ones.
	case emptyStringMatcher:
	case *equalStringMatcher:
	case *equalMultiStringSliceMatcher:
	case *equalMultiStringMapMatcher:
	case anyStringWithoutNewlineMatcher:
	case *anyNonEmptyStringMatcher:
	case trueMatcher:
	}
}

func TestToNormalisedLower(t *testing.T) {
	testCases := map[string]string{
		"foo":                      "foo",
		"FOO":                      "foo",
		"Foo":                      "foo",
		"foO":                      "foo",
		"fOo":                      "foo",
		"AAAAAAAAAAAAAAAAAAAAAAAA": "aaaaaaaaaaaaaaaaaaaaaaaa",
		"cccccccccccccccccccccccC": "cccccccccccccccccccccccc",
		"ſſſſſſſſſſſſſſſſſſſſſſſſS": "sssssssssssssssssssssssss",
		"ſſAſſa": "ssassa",
	}
	for input, expectedOutput := range testCases {
		require.Equal(t, expectedOutput, toNormalisedLower(input))
	}
}