Added missing tests for parquet rows normalizer (#1054)

src/adapter/etl-adapter-parquet/tests/Flow/ETL/Adapter/Parquet/Tests/Unit/RowsNormalizerTest.php

@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Flow\ETL\Adapter\Parquet\Tests\Unit;
+
+use function Flow\ETL\DSL\{row, rows, schema, str_entry, str_schema};
+use Flow\ETL\Adapter\Parquet\RowsNormalizer;
+use Flow\ETL\Exception\CastingException;
+use Flow\ETL\PHP\Type\Caster;
+use PHPUnit\Framework\TestCase;
+
+final class RowsNormalizerTest extends TestCase
+{
+    public function test_casting_error() : void
+    {
+        $this->expectException(CastingException::class);
+        $this->expectExceptionMessage("Can't cast \"NULL\" into \"string\" type");
+
+        $rows = rows(row(str_entry('id', null)));
+        $schema = schema(str_schema('id', nullable: false));
+
+        (new RowsNormalizer(Caster::default()))->normalize($rows, $schema);
+    }
+}