[GITEA] test markdown CleanValue to prevent regression

It will determine how anchors are created and will break existing
links otherwise.

Adapted from Revert "Make `user-content-* ` consistent with github (#26388)

(cherry picked from commit 1666fba8f5)
(cherry picked from commit 48f38280e8)
(cherry picked from commit 03adb3a2b4)
(cherry picked from commit a0ad36f0ad)
(cherry picked from commit 3aac990064)
(cherry picked from commit 137daabc9b)

modules/markup/common/footnote_test.go

@@ -0,0 +1,62 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// Copyright 2023 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+package common
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCleanValue(t *testing.T) {
+	tests := []struct {
+		param  string
+		expect string
+	}{
+		// Github behavior test cases
+		{"", ""},
+		{"test.0.1", "test-0-1"},
+		{"test(0)", "test-0"},
+		{"test!1", "test-1"},
+		{"test:2", "test-2"},
+		{"test*3", "test-3"},
+		{"test！4", "test-4"},
+		{"test：5", "test-5"},
+		{"test*6", "test-6"},
+		{"test：6 a", "test-6-a"},
+		{"test：6 !b", "test-6-b"},
+		{"test：ad # df", "test-ad-df"},
+		{"test：ad #23 df 2*/*", "test-ad-23-df-2"},
+		{"test：ad 23 df 2*/*", "test-ad-23-df-2"},
+		{"test：ad # 23 df 2*/*", "test-ad-23-df-2"},
+		{"Anchors in Markdown", "anchors-in-markdown"},
+		{"a_b_c", "a_b_c"},
+		{"a-b-c", "a-b-c"},
+		{"a-b-c----", "a-b-c"},
+		{"test：6a", "test-6a"},
+		{"test：a6", "test-a6"},
+		{"tes a a   a  a", "tes-a-a-a-a"},
+		{"  tes a a   a  a  ", "tes-a-a-a-a"},
+		{"Header with \"double quotes\"", "header-with-double-quotes"},
+		{"Placeholder to force scrolling on link's click", "placeholder-to-force-scrolling-on-link-s-click"},
+		{"tes（）", "tes"},
+		{"tes（0）", "tes-0"},
+		{"tes{0}", "tes-0"},
+		{"tes[0]", "tes-0"},
+		{"test【0】", "test-0"},
+		{"tes…@a", "tes-a"},
+		{"tes￥& a", "tes-a"},
+		{"tes= a", "tes-a"},
+		{"tes|a", "tes-a"},
+		{"tes\\a", "tes-a"},
+		{"tes/a", "tes-a"},
+		{"a啊啊b", "a啊啊b"},
+		{"c🤔️🤔️d", "c-d"},
+		{"a⚡a", "a-a"},
+		{"e.~f", "e-f"},
+	}
+	for _, test := range tests {
+		assert.Equal(t, []byte(test.expect), CleanValue([]byte(test.param)), test.param)
+	}
+}