minor #175 Throw bad method call on attempt to call ReadableEnumtrait…

…::readableForValue on non backed enum (ogizanagi)

This PR was merged into the 2.x-dev branch.

Discussion
----------

Throw bad method call on attempt to call ReadableEnumtrait::readableForValue on non backed enum

Commits
-------

b7b8ead Throw bad method call on attempt to call ReadableEnumtrait::readableForValue on non backed enum

.php-cs-fixer.php

@@ -18,6 +18,7 @@
         'tests/Fixtures/Enum/Suit.php',
         'tests/Fixtures/Enum/SuitWithAttributesMissingAttribute.php',
         'tests/Fixtures/Enum/SuitWithAttributes.php',
+        'tests/Fixtures/Enum/UnitSuit.php',
         'tests/Fixtures/Integration/Symfony/src/Enum/Suit.php',
     ])
 ;

src/ReadableEnumInterface.php

@@ -25,11 +25,10 @@ interface ReadableEnumInterface extends \UnitEnum
     public static function readables(): iterable;
 
     /**
-     * TODO: only for backed enums
+     * Gets the human representation for a given value (only for backed enum).
      *
-     * Gets the human representation for a given value.
-     *
-     * @throws \ValueError When $value is not acceptable for this enum
+     * @throws \ValueError             When $value is not acceptable for this enum
+     * @throws \BadMethodCallException When attempting to call this method on a non-backed enum.
      *
      * @return string The human representation for a given value
      */

src/ReadableEnumTrait.php

@@ -23,6 +23,14 @@ trait ReadableEnumTrait
      */
     public static function readableForValue(string|int $value): string
     {
+        if (!is_a(static::class, \BackedEnum::class, true)) {
+            throw new \BadMethodCallException(sprintf(
+                'Cannot call method "%s" on non-backed enum "%s".',
+                __METHOD__,
+                static::class,
+            ));
+        }
+
         /** @var ReadableEnumInterface $case */
         $case = static::from($value);
 

tests/Fixtures/Enum/UnitSuit.php

@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the "elao/enum" package.
+ *
+ * Copyright (C) Elao
+ *
+ * @author Elao <[email protected]>
+ */
+
+namespace Elao\Enum\Tests\Fixtures\Enum;
+
+use Elao\Enum\ReadableEnumInterface;
+use Elao\Enum\ReadableEnumTrait;
+
+enum UnitSuit implements ReadableEnumInterface
+{
+    use ReadableEnumTrait;
+
+    case Hearts;
+    case Diamonds;
+    case Clubs;
+    case Spades;
+
+    public static function readables(): iterable
+    {
+        yield self::Hearts => 'suit.hearts';
+        yield self::Diamonds => 'suit.diamonds';
+        yield self::Clubs => 'suit.clubs';
+        yield self::Spades => 'suit.spades';
+    }
+}

tests/Unit/ReadableEnumTest.php

@@ -14,6 +14,7 @@
 
 use Elao\Enum\Exception\NameException;
 use Elao\Enum\Tests\Fixtures\Enum\Suit;
+use Elao\Enum\Tests\Fixtures\Enum\UnitSuit;
 use PHPUnit\Framework\TestCase;
 
 class ReadableEnumTest extends TestCase
@@ -35,6 +36,14 @@ public function testReadableForValue(): void
         self::assertSame('suit.clubs', Suit::readableForValue(Suit::Clubs->value));
     }
 
+    public function testReadableForValueThrowOnUnitEnum(): void
+    {
+        $this->expectException(\BadMethodCallException::class);
+        $this->expectExceptionMessage('Cannot call method "Elao\Enum\ReadableEnumTrait::readableForValue" on non-backed enum "Elao\Enum\Tests\Fixtures\Enum\UnitSuit');
+
+        self::assertSame('suit.clubs', UnitSuit::readableForValue('C'));
+    }
+
     public function testReadableForValueExceptionOnInvalidName(): void
     {
         $this->expectException(\ValueError::class);