fix wrong auto-detection of country by language

src/main/java/net/datafaker/providers/base/PhoneNumber.java

@@ -80,29 +80,48 @@ private static String countryCodeIso2(Locale locale) {
     /**
      * A hack to detect country when only a language is given.
      * <p>
-     *     It's not correct because most languages are used in multiple countries.
-     *     If users need to generate random phone number, they should create locale with country,
-     *     e.g. {@code new Locale("ta_IN")}, and not just {@code new Locale("ta")}.
+     * It's not correct because most languages are used in multiple countries.
+     * If users need to generate random phone number, they should create locale with country,
+     * e.g. {@code new Locale("ta_IN")}, and not just {@code new Locale("ta")}.
      * </p>
      * <p>
-     *     We keep this mapping here just for backward compatibility.
+     * We keep this mapping here just for backward compatibility.
      * </p>
      */
     private static String detectCountryByLanguage(String language) {
         return switch (language) {
+            case "af" -> "ZA"; // Afrikaans language -> South Africa
+            case "ar" -> "SA"; // Arabic language -> Saudi Arabia (SA)
+            case "am" -> "ET"; // Amharic language -> Ethiopia (ET)
+            case "be" -> "BY"; // Belarus
+            case "bn" -> "BD"; // Bengali language -> Bangladesh (BD)
+            case "bs" -> "BA"; // Bosnian language -> Bosnia & Herzegovina (BA)
+            case "ca" -> "ES"; // Catalan language -> Spain (ES)
+            case "cy" -> "GB"; // Welsh language -> United Kingdom (GB)
+            case "cs" -> "CZ"; // Czech Republic
+            case "el" -> "GR"; // Greece
+            case "et" -> "EE"; // Estonian language -> Estonia (EE)
             case "en" -> "US"; // it has been used by default for English
-            case "test" -> "US"; // What the hell is "test" language?
+            case "eu" -> "ES"; // Basque (Basque Country | Spain)
+            case "fa" -> "IR"; // Persian language (Farsi) -> Iran (IR)
+            case "ga" -> "IE"; // Irish/Gaelic language -> Ireland (IE)
+            case "gl" -> "ES"; // Galician (Spain)
+            case "he" -> "IL"; // Israel
+            case "hi" -> "IN"; // Hindi language -> India
             case "hy" -> "AM"; // Armenia
-            case "uk" -> "UA"; // Ukraine
             case "ja" -> "JP"; // Japan
-            case "fa" -> "IR"; // Iran
             case "ka" -> "GE"; // Georgia
-            case "sq" -> "AL"; // Albania
-            case "cs" -> "CZ"; // Czech Republic
-            case "be" -> "BY"; // Belarus
+            case "km" -> "KH"; // Khmer language -> Cambodia (KH)
             case "ko" -> "KR"; // Korea
-            case "he" -> "IL"; // Israel
+            case "mo" -> "MD"; // Moldavian language -> Moldova
+            case "sq" -> "AL"; // Albania
+            case "sw" -> "TZ"; // Swahili language -> Tanzania (TZ)
+            case "ug" -> "CN"; // Uyghur language -> China (CN)
+            case "ur" -> "PK"; // Urdu language -> Pakistan (PK)
             case "ta" -> "IN"; // Tamil language -> India (though, Tamil is used in multiple countries)
+            case "test" -> "US"; // What the hell is "test" language?
+            case "uk" -> "UA"; // Ukraine
+            case "zh" -> "CN"; // Chinese language -> China (CN)
             default -> language.toUpperCase(ROOT);
         };
     }

src/test/java/net/datafaker/providers/base/PhoneNumberValidityFinderTest.java

@@ -9,6 +9,7 @@
 import org.junit.jupiter.api.TestInstance;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.CsvSource;
 import org.junit.jupiter.params.provider.MethodSource;
 
 import java.util.Locale;
@@ -53,6 +54,42 @@ void testLanguageOnlyPersianLocaleUsesIran() {
         assertThat(localFaker.phoneNumber().countryCodeIso2()).isEqualTo("IR");
     }
 
+    @ParameterizedTest
+    @CsvSource({
+        "en, US, English",
+        "hy, AM, Armenian → Armenia",
+        "uk, UA, Ukranian → Ukraine",
+        "ja, JP, Japanese → Japan",
+        "fa, IR, Persian (Farsi) → Iran",
+        "ka, GE, Georgia",
+        "sq, AL, Albanian → Albania",
+        "cs, CZ, Czech",
+        "be, BY, Belarusian",
+        "he, IL, Hebrew → Israel",
+        "ta, IN, Tamil → India",
+        "et, EE, Estonian → Estonia",
+        "el, GR, Greek → Greece",
+        "eu, ES, Basque → Spain",
+        "ca, ES, Catalan → Spain",
+        "cy, GB, Welsh → United Kingdom",
+        "ga, IE, Irish/Gaelic → Ireland",
+        "is, IS, Icelandic → Iceland",
+        "bs, BA, Bosnian → Bosnia & Herzegovina",
+        "ar, SA, Arabic → Saudi Arabia",
+        "hi, IN, Hindi → India",
+        "zh, CN, Chinese → China",
+        "am, ET, Amharic → Ethiopia",
+        "sw, TZ, Swahili → Tanzania",
+        "af, ZA, Afrikaans → South Africa",
+    })
+    void detectsCountryByLanguage(String language, String expectedCountry, String description) {
+        BaseFaker localFaker = new BaseFaker(new Locale(language));
+
+        assertThat(localFaker.phoneNumber().countryCodeIso2())
+            .as(description)
+            .isEqualTo(expectedCountry);
+    }
+
     @ParameterizedTest
     @MethodSource("allSupportedLocales")
     void testAllPhoneNumbers(Locale supportedLocale) throws NumberParseException {