fix(locale): only generate valid French postal codes

src/locales/fr/location/postcode.ts

@@ -1 +1,18 @@
-export default ['#####'];
+// French postal codes are five digits whose leading digits identify the
+// department: metropolitan departments use the prefixes 01-95 (followed by
+// three digits), while the overseas departments and collectivities use 971-978,
+// 984 and 986-989 (followed by two digits). The 00xxx, 96xxx, 980-983xx, 985xx
+// and 99xxx ranges are not assigned, so they are excluded here. See #3550 and
+// https://en.wikipedia.org/wiki/Postal_codes_in_France
+const range = (start: number, end: number): number[] =>
+  Array.from({ length: end - start + 1 }, (_, index) => start + index);
+
+const metropolitan = range(1, 95).map(
+  (department) => `${department.toString().padStart(2, '0')}###`
+);
+
+const overseas = [...range(971, 978), 984, ...range(986, 989)].map(
+  (territory) => `${territory}##`
+);
+
+export default [...metropolitan, ...overseas];

test/modules/location.spec.ts

@@ -8,6 +8,7 @@ import {
   faker,
   fakerEN_CA,
   fakerEN_US,
+  fakerFR,
   fakerNL,
   simpleFaker,
 } from '../../src';
@@ -222,6 +223,25 @@ describe('location', () => {
           }
         });
 
+        it('should only return valid department prefixes for fr locale', () => {
+          // French postal codes use department prefixes 01-95 (metropolitan)
+          // and 971-978/984/986-989 (overseas); 00xxx, 96xxx and 99xxx are not
+          // assigned. See https://github.com/faker-js/faker/issues/3550
+          const overseas = new Set([
+            971, 972, 973, 974, 975, 976, 977, 978, 984, 986, 987, 988, 989,
+          ]);
+
+          for (let i = 0; i < 1000; i++) {
+            const zipCode = fakerFR.location.zipCode();
+
+            expect(zipCode).toMatch(/^\d{5}$/);
+            const department = Number(zipCode.slice(0, 2));
+            const isMetropolitan = department >= 1 && department <= 95;
+            const isOverseas = overseas.has(Number(zipCode.slice(0, 3)));
+            expect(isMetropolitan || isOverseas).toBe(true);
+          }
+        });
+
         it.each([
           ['IL', 60001, 62999],
           ['GA', 30001, 31999],