IBX-12533: Fixed JsonToArrayTransformer rejecting empty string values

src/lib/Form/Transformer/JsonToArrayTransformer.php

@@ -34,7 +34,7 @@ public function transform($value)
 
     public function reverseTransform($value)
     {
-        if ($value === null) {
+        if ($value === null || $value === '') {
             return [];
         }
 

tests/lib/Form/Transformer/JsonToArrayTransformerTest.php

@@ -0,0 +1,67 @@
+<?php
+
+/**
+ * @copyright Copyright (C) Ibexa AS. All rights reserved.
+ * @license For full copyright and license information view LICENSE file distributed with this source code.
+ */
+declare(strict_types=1);
+
+namespace Ibexa\Tests\ContentForms\Form\Transformer;
+
+use Ibexa\ContentForms\Form\Transformer\JsonToArrayTransformer;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Form\Exception\TransformationFailedException;
+
+final class JsonToArrayTransformerTest extends TestCase
+{
+    /**
+     * @return iterable<string, array{mixed, string}>
+     */
+    public static function provideDataForTestTransform(): iterable
+    {
+        yield 'null value' => [null, ''];
+        yield 'associative array' => [['foo' => 'bar'], '{"foo":"bar"}'];
+        yield 'empty array' => [[], '{}'];
+    }
+
+    /**
+     * @param string[]|null $value
+     * @dataProvider provideDataForTestTransform
+     */
+    public function testTransform(?array $value, string $expected): void
+    {
+        $transformer = new JsonToArrayTransformer();
+
+        self::assertSame($expected, $transformer->transform($value));
+    }
+
+    /**
+     * @return iterable<string, array{string|null, mixed}>
+     */
+    public static function provideDataForTestReverseTransform(): iterable
+    {
+        yield 'null value' => [null, []];
+        yield 'empty string' => ['', []];
+        yield 'JSON string' => ['{"foo":"bar"}', ['foo' => 'bar']];
+        yield 'zero string' => ['0', 0];
+    }
+
+    /**
+     * @param string[]|int $expected
+     * @dataProvider provideDataForTestReverseTransform
+     */
+    public function testReverseTransform(?string $value, $expected): void
+    {
+        $transformer = new JsonToArrayTransformer();
+
+        self::assertSame($expected, $transformer->reverseTransform($value));
+    }
+
+    public function testReverseTransformInvalidJsonThrowsException(): void
+    {
+        $transformer = new JsonToArrayTransformer();
+
+        $this->expectException(TransformationFailedException::class);
+        $transformer->reverseTransform('{invalid}');
+    }
+}