Migrate Country.flag() from deprecated flags.fmcdn.net to flagcdn.com; add overload

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

@@ -1,27 +1,50 @@
 package net.datafaker.providers.base;
 
+import java.util.Locale;
+
 /**
  * Provides methods for generating country-related data such as names, codes, capitals, and flags.
  * <p>
  * This provider is backed by the data defined in {@code country.yml}.
+ * <p>
+ * Flag images are served by <a href="https://flagcdn.com">flagcdn.com</a>
+ * (see <a href="https://flagpedia.net/download/api">Flagpedia API</a>).
  *
  * @since 0.8.0
  */
 public class Country extends AbstractProvider<BaseProviders> {
-    private final String flagUrl;
+
+    private static final String FLAG_BASE_URL = "https://flagcdn.com/";
 
     protected Country(BaseProviders faker) {
         super(faker);
-        this.flagUrl = "https://flags.fmcdn.net/data/flags/w580/";
     }
 
     /**
-     * Generates a URL pointing to the flag image of a random country.
+     * Generates a <em>PNG</em> flag URL for a random country at size ({@code w580}).
      *
      * @return a flag image URL string
      */
     public String flag() {
-        return flagUrl + resolve("country.code2") + ".png";
+        return flag("w580", ImageFormat.PNG);
+    }
+
+    /**
+     * Generates a flag URL for a random country.
+     * <p>
+     * For {@link ImageFormat#SVG} the {@code size} argument is ignored.<br>
+     * See the <a href="https://flagpedia.net/download/api">Flagpedia API</a> for valid size strings.
+     *
+     * @param size   a {@code flagcdn.com} size string, e.g. {@code "w320"}, {@code "h80"}, {@code "32x24"}
+     * @param format the desired image format
+     * @return a flag image URL string
+     */
+    public String flag(String size, ImageFormat format) {
+        String url = FLAG_BASE_URL;
+        if (ImageFormat.SVG != format) {
+            url += size + '/';
+        }
+        return url + countryCode2() + '.' + format.getExtension();
     }
 
     /**
@@ -76,4 +99,24 @@ public String name() {
         return resolve("country.name");
     }
 
+    /**
+     * Image format for flag URLs.
+     */
+    public enum ImageFormat {
+        JPG,
+        PNG,
+        SVG,
+        WEBP;
+
+        private final String extension;
+
+        ImageFormat() {
+            this.extension = name().toLowerCase(Locale.ROOT);
+        }
+
+        public String getExtension() {
+            return extension;
+        }
+    }
+
 }

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

@@ -1,21 +1,37 @@
 package net.datafaker.providers.base;
 
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatNoException;
+
 import org.junit.jupiter.api.RepeatedTest;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.EnumSource;
+import org.junit.jupiter.params.provider.ValueSource;
 
+import java.net.URL;
 import java.util.Collection;
 import java.util.List;
 
-import static org.assertj.core.api.Assertions.assertThat;
-
 class CountryTest extends BaseFakerTest {
 
     private final Country country = faker.country();
 
     @RepeatedTest(10)
     void testFlag() {
-        String flag = country.flag();
-        assertThat(flag).matches("^https://flags.fmcdn\\.net/data/flags/w580/[a-zA-Z0-9_]+\\.png$");
+        assertThat(country.flag()).matches("^https://flagcdn\\.com/w580/[a-z]{2}+\\.png$");
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = {"w580", "w320", "h80", "32x24"})
+    void testFlagWithSizeProducesValidUrl(String size) {
+        assertThatNoException().isThrownBy(() -> new URL(country.flag(size, Country.ImageFormat.PNG)));
+    }
+
+    @ParameterizedTest
+    @EnumSource(Country.ImageFormat.class)
+    void testFlagWithFormatProducesValidUrl(Country.ImageFormat format) {
+        assertThatNoException().isThrownBy(() -> new URL(country.flag("w320", format)));
     }
 
     @Test