Add regression test for timestamps being included in the data column

tests/VirtualColumnTest.php

@@ -157,6 +157,28 @@ class VirtualColumnTest extends TestCase
         // Reset static property
         MyModel::$customEncryptedCastables = [];
     }
+
+    public function testUpdatingModelDoesNotStoreTimestampsInTheVirtualColumn() {
+        /** @var TimestampModel $model */
+        $model = TimestampModel::create();
+        $dbRecordDataColumn = fn () => DB::selectOne('select * from timestamp_models where id = ?', [$model->id])->data;
+
+        $this->assertStringNotContainsString('created_at', $dbRecordDataColumn());
+        $this->assertStringNotContainsString('updated_at', $dbRecordDataColumn());
+
+        $model->update(['data' => ['virtual' => 'bar']]);
+
+        $this->assertStringNotContainsString('created_at', $dbRecordDataColumn());
+        $this->assertStringNotContainsString('updated_at', $dbRecordDataColumn());
+    }
+}
+
+class TimestampModel extends Model
+{
+    use VirtualColumn;
+
+    public $timestamps = true;
+    protected $guarded = [];
 }
 
 class ParentModel extends Model

tests/etc/migrations/2020_05_11_000001_create_timestamp_models_table.php

@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+class CreateTimestampModelsTable extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up()
+    {
+        Schema::create('timestamp_models', function (Blueprint $table) {
+            $table->increments('id');
+
+            $table->timestamps();
+            $table->json('data');
+        });
+    }
+
+    public function down()
+    {
+        Schema::dropIfExists('timestamp_models');
+    }
+}