[9.x] Improves $request->enum() type API (#44370)

* improve input enum method

* type test for input enum method

* Apply fixes from StyleCI

* Fixes types tests and improves wording of generics

Co-authored-by: SupunKavinda <[email protected]>
Co-authored-by: StyleCI Bot <[email protected]>

Author: 3 people

src/Illuminate/Http/Concerns/InteractsWithInput.php

@@ -372,9 +372,11 @@ public function date($key, $format = null, $tz = null)
     /**
      * Retrieve input from the request as an enum.
      *
+     * @template TEnum
+     *
      * @param  string  $key
-     * @param  string  $enumClass
-     * @return mixed|null
+     * @param  class-string<TEnum>  $enumClass
+     * @return TEnum|null
      */
     public function enum($key, $enumClass)
     {

types/Http/Request.php

@@ -0,0 +1,14 @@
+<?php
+
+use Illuminate\Http\Request;
+use function PHPStan\Testing\assertType;
+
+class TestEnum
+{
+}
+
+$request = Request::create('/', 'GET', [
+    'key' => 'test',
+]);
+
+assertType('TestEnum|null', $request->enum('key', TestEnum::class));