Add support for 4-digit LB postcodes

Author: BenMorel

src/Formatter/LBFormatter.php

@@ -16,16 +16,21 @@
  * Postcode format is NNNN NNNN, where N stands for a digit.
  *
  * @see https://en.wikipedia.org/wiki/List_of_postal_codes
+ * @see https://github.com/brick/postcode/issues/22
  */
 final class LBFormatter implements CountryPostcodeFormatter
 {
     #[Override]
     public function format(string $postcode): ?string
     {
-        if (preg_match('/^[0-9]{8}$/', $postcode) !== 1) {
-            return null;
+        if (preg_match('/^[0-9]{4}$/', $postcode) === 1) {
+            return $postcode;
         }
 
-        return substr($postcode, 0, 4) . ' ' . substr($postcode, 4);
+        if (preg_match('/^[0-9]{8}$/', $postcode) === 1) {
+            return substr($postcode, 0, 4) . ' ' . substr($postcode, 4);
+        }
+
+        return null;
     }
 }

tests/Formatter/LBFormatterTest.php

@@ -22,7 +22,7 @@ public static function providerFormat(): array
             ['12', null],
             ['012', null],
             ['123', null],
-            ['1234', null],
+            ['1234', '1234'],
             ['01234', null],
             ['12345', null],
             ['123456', null],