Add Backed Enum test case

In the Enumeration RFC, it states Backed Enums can implement
interfaces, but it was not clear where the backed Enum type
would need to be placed in such situation.

This commit adds a test case for this scenario.

Signed-off-by: Agustin Gomes <[email protected]>

Author: agustingomes

Zend/tests/enum/backed-implements.phpt

@@ -0,0 +1,34 @@
+--TEST--
+Backed Enum implements
+--FILE--
+<?php
+
+interface Colorful {
+    public function color(): string;
+}
+
+enum Suit: string implements Colorful {
+    case Hearts = 'H';
+    case Diamonds = 'D';
+    case Clubs = 'C';
+    case Spades = 'S';
+
+    public function color(): string {
+        return match ($this) {
+            self::Hearts, self::Diamonds => 'Red',
+            self::Clubs, self::Spades => 'Black',
+        };
+    }
+}
+
+echo Suit::Hearts->color() . "\n";
+echo Suit::Diamonds->color() . "\n";
+echo Suit::Clubs->color() . "\n";
+echo Suit::Spades->color() . "\n";
+
+?>
+--EXPECT--
+Red
+Red
+Black
+Black