Change how to stringify enumerations

Currently, the `ObjectStringifier` is taking care of enumerations, but
it's better to clarify that the raw value is an enumeration rather than
treat it as an object.

The representation might be confused with a constant, but that's how PHP
does anyways.

Signed-off-by: Henrique Moody <henriquemoody@gmail.com>

Author: henriquemoody

src/Stringifiers/ClusterStringifier.php

@@ -53,6 +53,7 @@ public static function createDefault(): self
             new ThrowableObjectStringifier($jsonEncodableStringifier, $quoter),
             new StringableObjectStringifier($jsonEncodableStringifier, $quoter),
             new JsonSerializableObjectStringifier($jsonEncodableStringifier, $quoter),
+            new EnumerationStringifier($quoter),
             new ObjectWithDebugInfoStringifier($arrayStringifier, $quoter),
             new ObjectStringifier($stringifier, $quoter, self::MAXIMUM_DEPTH, self::MAXIMUM_NUMBER_OF_PROPERTIES),
             $arrayStringifier,

src/Stringifiers/EnumerationStringifier.php

@@ -0,0 +1,34 @@
+<?php
+
+/*
+ * This file is part of Respect/Stringifier.
+ * Copyright (c) Henrique Moody <henriquemoody@gmail.com>
+ * SPDX-License-Identifier: MIT
+ */
+
+declare(strict_types=1);
+
+namespace Respect\Stringifier\Stringifiers;
+
+use Respect\Stringifier\Quoter;
+use Respect\Stringifier\Stringifier;
+use UnitEnum;
+
+use function sprintf;
+
+final class EnumerationStringifier implements Stringifier
+{
+    public function __construct(
+        private readonly Quoter $quoter
+    ) {
+    }
+
+    public function stringify(mixed $raw, int $depth): ?string
+    {
+        if (!$raw instanceof UnitEnum) {
+            return null;
+        }
+
+        return $this->quoter->quote(sprintf('%s::%s', $raw::class, $raw->name), $depth);
+    }
+}

tests/fixtures/BackedEnumeration.php

@@ -0,0 +1,15 @@
+<?php
+
+/*
+ * This file is part of Respect/Stringifier.
+ * Copyright (c) Henrique Moody <henriquemoody@gmail.com>
+ * SPDX-License-Identifier: MIT
+ */
+
+declare(strict_types=1);
+
+enum BackedEnumeration: string
+{
+    case BAZ = 'baz';
+    case QUX = 'qux';
+}

tests/fixtures/BasicEnumeration.php

@@ -0,0 +1,15 @@
+<?php
+
+/*
+ * This file is part of Respect/Stringifier.
+ * Copyright (c) Henrique Moody <henriquemoody@gmail.com>
+ * SPDX-License-Identifier: MIT
+ */
+
+declare(strict_types=1);
+
+enum BasicEnumeration
+{
+    case FOO;
+    case BAR;
+}

tests/integration/stringify-enumeration.phpt

@@ -0,0 +1,15 @@
+--FILE--
+<?php
+
+declare(strict_types=1);
+
+require 'vendor/autoload.php';
+
+outputMultiple(
+    BasicEnumeration::FOO,
+    BackedEnumeration::QUX,
+);
+?>
+--EXPECT--
+`BasicEnumeration::FOO`
+`BackedEnumeration::QUX`

tests/unit/Stringifiers/EnumerationStringifierTest.php

@@ -0,0 +1,59 @@
+<?php
+
+/*
+ * This file is part of Respect/Stringifier.
+ * Copyright (c) Henrique Moody <henriquemoody@gmail.com>
+ * SPDX-License-Identifier: MIT
+ */
+
+declare(strict_types=1);
+
+namespace Respect\Stringifier\Test\Unit\Stringifiers;
+
+use BackedEnumeration;
+use BasicEnumeration;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\Test;
+use PHPUnit\Framework\TestCase;
+use Respect\Stringifier\Stringifiers\EnumerationStringifier;
+use Respect\Stringifier\Test\Double\FakeQuoter;
+
+#[CoversClass(EnumerationStringifier::class)]
+final class EnumerationStringifierTest extends TestCase
+{
+    private const DEPTH = 0;
+
+    #[Test]
+    public function itShouldNotStringifyWhenRawValueIsNotAnEnumeration(): void
+    {
+        $sut = new EnumerationStringifier(new FakeQuoter());
+
+        self::assertNull($sut->stringify(1, self::DEPTH));
+    }
+
+    #[Test]
+    public function itShouldStringifyRawValueWhenItIsBasicEnumeration(): void
+    {
+        $quoter = new FakeQuoter();
+
+        $sut = new EnumerationStringifier($quoter);
+
+        $actual = $sut->stringify(BasicEnumeration::BAR, self::DEPTH);
+        $expected = $quoter->quote('BasicEnumeration::BAR', self::DEPTH);
+
+        self::assertSame($expected, $actual);
+    }
+
+    #[Test]
+    public function itShouldStringifyRawValueWhenItIsBackedEnumeration(): void
+    {
+        $quoter = new FakeQuoter();
+
+        $sut = new EnumerationStringifier($quoter);
+
+        $actual = $sut->stringify(BackedEnumeration::BAZ, self::DEPTH);
+        $expected = $quoter->quote('BackedEnumeration::BAZ', self::DEPTH);
+
+        self::assertSame($expected, $actual);
+    }
+}