EloquentModelDateCastingTest.php

<?php

namespace Illuminate\Tests\Integration\Database\EloquentModelDateCastingTest;

use Illuminate\Contracts\Database\Eloquent\CastsAttributes;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;
use Illuminate\Tests\Integration\Database\DatabaseTestCase;

class EloquentModelDateCastingTest extends DatabaseTestCase
{
    protected function defineDatabaseMigrationsAfterDatabaseRefreshed()
    {
        Schema::create('test_model1', function (Blueprint $table) {
            $table->increments('id');
            $table->date('date_field')->nullable();
        });
    }

    public function testDirtyWithNewInstance()
    {
        $model = new TestModel1;

        $this->assertFalse($model->wasChanged('date_field')); // ok
        $this->assertFalse($model->isDirty('date_field')); // ok
        $this->assertTrue($model->isClean('date_field')); // ok

        $some = $model->date_field;

        $this->assertFalse($model->wasChanged('date_field')); // ok
        $this->assertFalse($model->isDirty('date_field')); // failed
        $this->assertTrue($model->isClean('date_field')); // failed
    }

    public function testDirtyAfterFind()
    {
        TestModel1::create([
            'date_field' => '2019-10-01',
        ]);

        $model = TestModel1::first();

        $some = $model->date_field;

        $this->assertArrayNotHasKey('date_field', $model->getDirty());
    }
}

class TestModel1 extends Model
{
    public $table = 'test_model1';
    public $timestamps = false;
    protected $guarded = [];

    public $casts = [
        'date_field' => DateObjectCaster::class,
    ];
}

class DateObjectCaster implements CastsAttributes
{
    public function get($model, $key, $value, $attributes)
    {
        return \Illuminate\Support\Carbon::createFromDate($value);
    }

    public function set($model, $key, $value, $attributes)
    {
        return $value;
    }
}