Add Czech language (#59)

* feat: add czech language

* fix: fix wrong czech word for symbol @

languages_substitution.go

@@ -10,6 +10,7 @@ func init() {
 	// TODO: Find better way so all langs are merged automatically and better
 	// tested.
 	for _, sub := range []*map[rune]string{
+		&csSub,
 		&deSub,
 		&enSub,
 		&esSub,
@@ -41,6 +42,11 @@ var defaultSub = map[rune]string{
 	'―':  "-", // horizontal bar
 }
 
+var csSub = map[rune]string{
+	'&': "a",
+	'@': "zavinac",
+}
+
 var deSub = map[rune]string{
 	'&': "und",
 	'@': "an",

slug.go

@@ -57,6 +57,8 @@ func MakeLang(s string, lang string) (slug string) {
 	// Process string with selected substitution language.
 	// Catch ISO 3166-1, ISO 639-1:2002 and ISO 639-3:2007.
 	switch strings.ToLower(lang) {
+	case "cs", "ces":
+		slug = SubstituteRune(slug, csSub)
 	case "de", "deu":
 		slug = SubstituteRune(slug, deSub)
 	case "en", "eng":

slug_test.go

@@ -23,16 +23,18 @@ func TestSlugMake(t *testing.T) {
 		{"Ala ma 6 kotów.", "ala-ma-6-kotow"},
 
 		{"áÁàÀãÃâÂäÄąĄą̊Ą̊", "aaaaaaaaaaaaaa"},
-		{"ćĆĉĈçÇ", "cccccc"},
-		{"éÉèÈẽẼêÊëËęĘ", "eeeeeeeeeeee"},
+		{"ćĆĉĈçÇčČ", "cccccccc"},
+		{"éÉèÈẽẼêÊëËęĘěĚ", "eeeeeeeeeeeeee"},
 		{"íÍìÌĩĨîÎïÏįĮ", "iiiiiiiiiiii"},
 		{"łŁ", "ll"},
 		{"ńŃ", "nn"},
 		{"óÓòÒõÕôÔöÖǫǪǭǬø", "ooooooooooooooo"},
-		{"śŚ", "ss"},
-		{"úÚùÙũŨûÛüÜųŲ", "uuuuuuuuuuuu"},
-		{"y̨Y̨", "yy"},
-		{"źŹżŹ", "zzzz"},
+		{"śŚšŠ", "ssss"},
+		{"řŘ", "rr"},
+		{"ťŤ", "tt"},
+		{"úÚùÙũŨûÛüÜųŲůŮ", "uuuuuuuuuuuuuu"},
+		{"y̨Y̨ýÝ", "yyyy"},
+		{"źŹżŹžŽ", "zzzzzz"},
 		{"·/,:;`˜'\"", ""},
 		{"2000–2013", "2000-2013"},
 		{"style—not", "style-not"},
@@ -71,6 +73,10 @@ func TestSlugMakeLang(t *testing.T) {
 		want      string
 		lowercase bool
 	}{
+		{"cs", "ěščřžýáíéúůóňťĚŠČŘŽÝÁÍÉÚŮÓŇŤ", "escrzyaieuuontescrzyaieuuont", true},
+		{"cs", "ěščřžýáíéúůóňťĚŠČŘŽÝÁÍÉÚŮÓŇŤ", "escrzyaieuuontESCRZYAIEUUONT", false},
+		{"ces", "ěščřžýáíéúůóňťĚŠČŘŽÝÁÍÉÚŮÓŇŤ", "escrzyaieuuontescrzyaieuuont", true},
+		{"ces", "ěščřžýáíéúůóňťĚŠČŘŽÝÁÍÉÚŮÓŇŤ", "escrzyaieuuontESCRZYAIEUUONT", false},
 		{"de", "Wir mögen Bücher & Käse", "wir-moegen-buecher-und-kaese", true},
 		{"de", "Wir mögen Bücher & Käse", "Wir-moegen-Buecher-und-Kaese", false},
 		{"de", "Äpfel Über Österreich", "aepfel-ueber-oesterreich", true},
@@ -86,6 +92,14 @@ func TestSlugMakeLang(t *testing.T) {
 		{"kk", "әғһіңөқұүӘҒҺІҢӨҚҰҮ", "aghinoquuaghinoquu", true},
 		{"kk", "әғһіңөқұүӘҒҺІҢӨҚҰҮ", "aghinoquuAGHINOQUU", false},
 		// & fun.
+		{"cs", "Toto & Tamto", "toto-a-tamto", true},
+		{"cs", "Toto & Tamto", "Toto-a-Tamto", false},
+		{"cs", "Toto @ Tamto", "toto-zavinac-tamto", true},
+		{"cs", "Toto @ Tamto", "Toto-zavinac-Tamto", false},
+		{"ces", "Toto & Tamto", "toto-a-tamto", true},
+		{"ces", "Toto & Tamto", "Toto-a-Tamto", false},
+		{"ces", "Toto @ Tamto", "toto-zavinac-tamto", true},
+		{"ces", "Toto @ Tamto", "Toto-zavinac-Tamto", false},
 		{"de", "This & that", "this-und-that", true},
 		{"en", "This & that", "this-and-that", true},
 		{"es", "This & that", "this-y-that", true},
@@ -116,6 +130,7 @@ func TestSlugMakeLang(t *testing.T) {
 		{"test", "This & that", "this-and-that", true}, // unknown lang, fallback to "en"
 		// Test defaultSub, when adding new lang copy/paste this line,
 		// it contain special characters.
+		{"cs", "1\"2'3’4‒5–6—7―8", "1234-5-6-7-8", true},
 		{"de", "1\"2'3’4‒5–6—7―8", "1234-5-6-7-8", true},
 		{"en", "1\"2'3’4‒5–6—7―8", "1234-5-6-7-8", true},
 		{"es", "1\"2'3’4‒5–6—7―8", "1234-5-6-7-8", true},
@@ -151,6 +166,8 @@ func TestSlugMakeUserSubstituteLang(t *testing.T) {
 	}{
 		{map[string]string{"'": " "}, "en", "That's great", "that-s-great"},
 		{map[string]string{"&": "or"}, "en", "This & that", "this-or-that"},                   // by default "&" => "and"
+		{map[string]string{"&": "or"}, "cs", "This & that", "this-or-that"},                   // by default "&" => "a"
+		{map[string]string{"&": "or"}, "ces", "This & that", "this-or-that"},                  // by default "&" => "a"
 		{map[string]string{"&": "or"}, "de", "This & that", "this-or-that"},                   // by default "&" => "und"
 		{map[string]string{"&": "or"}, "DEU", "This & that", "this-or-that"},                  // by default "&" => "und"
 		{map[string]string{"&": "or"}, "Fin", "This & that", "this-or-that"},                  // by default "&" => "ja"