Fix a warning when DateTime column has empty value

src/DataIntegrity.php

@@ -215,7 +215,7 @@ public static function coerceValueToColumn(
                         $value .= ' 00:00:00';
                     }
 
-                    if ($value[0] === '-' || $value === '') {
+                    if ($value === '' || $value[0] === '-') {
                         $value = '0000-00-00 00:00:00';
                     } elseif (\preg_match(
                         '/^([0-9]{2,4}-[0-1][0-9]-[0-3][0-9]|[0-9]+)$/',

tests/DataIntegrityTest.php

@@ -0,0 +1,32 @@
+<?php
+
+namespace Vimeo\MysqlEngine\Tests;
+
+use PHPUnit\Framework\TestCase;
+use Vimeo\MysqlEngine\DataIntegrity;
+use Vimeo\MysqlEngine\FakePdoInterface;
+use Vimeo\MysqlEngine\Php7\FakePdo;
+use Vimeo\MysqlEngine\Schema\Column\DateTime;
+use const PHP_MAJOR_VERSION;
+
+class DataIntegrityTest extends TestCase
+{
+
+    public function testEmptyDateTimeColumnShouldReturnDefaultDate()
+    {
+        $dateTimeColumn = new DateTime();
+
+        $result = DataIntegrity::coerceValueToColumn($this->getPdo(), $dateTimeColumn, '');
+
+        $this->assertEquals('0000-00-00 00:00:00', $result);
+    }
+
+    private static function getPdo(): FakePdoInterface
+    {
+        if (PHP_MAJOR_VERSION === 8) {
+            return new \Vimeo\MysqlEngine\Php8\FakePdo('mysql:foo;dbname=test;');
+        }
+
+        return new FakePdo('mysql:foo;dbname=test;');
+    }
+}