Add support for Nigeria's 11-character postcodes

src/Formatter/NGFormatter.php

@@ -7,13 +7,18 @@
 use Brick\Postcode\CountryPostcodeFormatter;
 use Override;
 
+use function array_slice;
+use function implode;
 use function preg_match;
 
 /**
  * Validates and formats postcodes in Nigeria.
  *
- * Postal codes in Nigeria are numeric, consisting of six digits.
+ * The digital postcode NIPOST launched in October 2026 has 11 characters, AA-NN-XXX-AA-NN,
+ * where A stands for a letter, N for a digit and X for either. Both numeric segments
+ * run from 01 to 99. The former six-digit code is still accepted.
  *
+ * @see https://docs.postcode.gov.ng/concepts/postcode-format
  * @see https://en.wikipedia.org/wiki/List_of_postal_codes
  * @see https://en.wikipedia.org/wiki/Postal_codes_in_Nigeria
  */
@@ -22,10 +27,16 @@ final class NGFormatter implements CountryPostcodeFormatter
     #[Override]
     public function format(string $postcode): ?string
     {
-        if (preg_match('/^[0-9]{6}$/', $postcode) !== 1) {
+        if (preg_match('/^[0-9]{6}$/', $postcode) === 1) {
+            return $postcode;
+        }
+
+        $pattern = '/^([A-Z]{2})(0[1-9]|[1-9][0-9])([A-Z0-9]{3})([A-Z]{2})(0[1-9]|[1-9][0-9])$/';
+
+        if (preg_match($pattern, $postcode, $matches) !== 1) {
             return null;
         }
 
-        return $postcode;
+        return implode('-', array_slice($matches, 1));
     }
 }

tests/Formatter/NGFormatterTest.php

@@ -33,6 +33,17 @@ public static function providerFormat(): array
             ['ABCDE', null],
             ['ABCDEF', null],
             ['ABCDEFG', null],
+
+            ['EK01A03FK01', 'EK-01-A03-FK-01'],
+            ['FC03B06AG12', 'FC-03-B06-AG-12'],
+            ['LA99ZZZTC99', 'LA-99-ZZZ-TC-99'],
+            ['EK00A03FK01', null],
+            ['EK01A03FK00', null],
+            ['EK01A03FK1', null],
+            ['EK01A03FK011', null],
+            ['E101A03FK01', null],
+            ['EKA1A03FK01', null],
+            ['EK01A03F101', null],
         ];
     }