[Console] Fixed #29835: ConfirmationQuestion with default true for answer '0'

src/Symfony/Component/Console/Question/ConfirmationQuestion.php

@@ -53,7 +53,7 @@ private function getDefaultNormalizer()
                 return $answer && $answerIsTrue;
             }
 
-            return !$answer || $answerIsTrue;
+            return '' === $answer || $answerIsTrue;
         };
     }
 }

src/Symfony/Component/Console/Tests/Question/ConfirmationQuestionTest.php

@@ -0,0 +1,62 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Console\Tests\Question;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Console\Question\ConfirmationQuestion;
+
+class ConfirmationQuestionTest extends TestCase
+{
+    /**
+     * @dataProvider normalizerUsecases
+     */
+    public function testDefaultRegexUsecases($default, $answers, $expected, $message)
+    {
+        $sut = new ConfirmationQuestion('A question', $default);
+
+        foreach ($answers as $answer) {
+            $normalizer = $sut->getNormalizer();
+            $actual = $normalizer($answer);
+            $this->assertEquals($expected, $actual, sprintf($message, $answer));
+        }
+    }
+
+    public function normalizerUsecases()
+    {
+        return [
+            [
+                true,
+                ['y', 'Y', 'yes', 'YES', 'yEs', ''],
+                true,
+                'When default is true, the normalizer must return true for "%s"',
+            ],
+            [
+                true,
+                ['n', 'N', 'no', 'NO', 'nO', 'foo', '1', '0'],
+                false,
+                'When default is true, the normalizer must return false for "%s"',
+            ],
+            [
+                false,
+                ['y', 'Y', 'yes', 'YES', 'yEs'],
+                true,
+                'When default is false, the normalizer must return true for "%s"',
+            ],
+            [
+                false,
+                ['n', 'N', 'no', 'NO', 'nO', 'foo', '1', '0', ''],
+                false,
+                'When default is false, the normalizer must return false for "%s"',
+            ],
+        ];
+    }
+}