Fix failing enum mapping for backed PHP enums

Author: ioigoume

src/JsonMapper.php

@@ -296,12 +296,20 @@ public function map($json, $object)
             } else if (is_array($jvalue) && $this->hasVariadicArrayType($accessor)) {
                 $array = array();
                 $subtype = $type;
-            } else {
-                if (is_a($type, 'ArrayAccess', true)
-                    && is_a($type, 'Traversable', true)
-                ) {
-                    $array = $this->createInstance($type, false, $jvalue);
+            } else if (is_a($type, 'ArrayAccess', true)
+                && is_a($type, 'Traversable', true)
+            ) {
+                $array = $this->createInstance($type, false, $jvalue);
+            } else if (PHP_VERSION_ID >= 80100 && enum_exists($type)) {
+                $evalue = $type::tryFrom($jvalue);
+                if ($evalue === null) {
+                    throw new JsonMapper_Exception(
+                        'Enum value "' . $jvalue . '" does not belong to '
+                        . $type . ' enumerator class'
+                    );
                 }
+                $this->setProperty($object, $accessor, $evalue);
+                continue;
             }
 
             if ($array !== null) {

tests/Enums_PHP81_Test.php

@@ -32,4 +32,45 @@ public function testEnumMapping()
         $this->assertSame(\Enums\StringBackedEnum::FOO, $sn->stringBackedEnum);
         $this->assertSame(\Enums\IntBackedEnum::BAR, $sn->intBackedEnum);
     }
+
+    /**
+     * Test that string values are correctly mapped to backed enum properties.
+     */
+    public function testBackedEnumPropertyIsMappedFromString(): void
+    {
+        $json = (object) [
+            'stringBackedEnum' => 'foo',
+            'intBackedEnum' => 2,
+        ];
+
+        $mapper = new \JsonMapper();
+        $target = new \Enums\ObjectWithEnum();
+
+        $mapped = $mapper->map($json, $target);
+
+        $this->assertSame(
+            \Enums\StringBackedEnum::FOO,
+            $mapped->stringBackedEnum,
+            'Expected JSON scalar to be converted to the corresponding backed enum case'
+        );
+    }
+
+    /**
+     * Test that mapping invalid string values to backed enum properties throws an exception.
+     */
+    public function testBackedEnumPropertyWithInvalidStringThrowsJsonMapperException(): void
+    {
+        $json = (object) [
+            'stringBackedEnum' => 'not-a-valid-enum-value',
+            'intBackedEnum' => 'not-a-valid-enum-value',
+        ];
+
+        $mapper = new \JsonMapper();
+        $target = new \Enums\ObjectWithEnum();
+
+        $this->expectException(\JsonMapper_Exception::class);
+        $this->expectExceptionMessage('Enum value "not-a-valid-enum-value" does not belong to');
+
+        $mapper->map($json, $target);
+    }
 }