diff --git a/tests/unit/Converter/ClassTransformersTest.php b/tests/unit/Converter/ClassTransformersTest.php
new file mode 100644
index 0000000..2b84da8
--- /dev/null
+++ b/tests/unit/Converter/ClassTransformersTest.php
@@ -0,0 +1,51 @@
+<?php
+
+namespace Rinsvent\Data2DTO\Tests\Converter;
+
+use Rinsvent\Data2DTO\Data2DtoConverter;
+use Rinsvent\Data2DTO\Tests\unit\Converter\fixtures\FillTest\HelloClassTransformersRequest;
+use Rinsvent\Data2DTO\Tests\unit\Converter\fixtures\FillTest\HelloClassTransformersRequest2;
+use Rinsvent\Data2DTO\Tests\unit\Converter\fixtures\FillTest\HelloTagsRequest;
+
+class ClassTransformersTest extends \Codeception\Test\Unit
+{
+    /**
+     * @var \UnitTester
+     */
+    protected $tester;
+
+    protected function _before()
+    {
+    }
+
+    protected function _after()
+    {
+    }
+
+    // tests
+    public function testSuccessWithReturnData()
+    {
+        $data2DtoConverter = new Data2DtoConverter();
+
+        $data = [
+            'surname' => 'Surname1234',
+            'age' => 3,
+        ];
+        $dto = $data2DtoConverter->convert($data, new HelloClassTransformersRequest);
+        $this->assertInstanceOf(HelloClassTransformersRequest::class, $dto);
+        $this->assertEquals(123454321, $dto->surname);
+    }
+
+    public function testSuccessWithReturnObject()
+    {
+        $data2DtoConverter = new Data2DtoConverter();
+
+        $data = [
+            'surname' => 'Surname1234',
+            'age' => 3,
+        ];
+        $dto = $data2DtoConverter->convert($data, new HelloClassTransformersRequest2());
+        $this->assertInstanceOf(HelloClassTransformersRequest2::class, $dto);
+        $this->assertEquals(98789, $dto->surname);
+    }
+}
diff --git a/tests/unit/Converter/DataObjectTest.php b/tests/unit/Converter/DataObjectTest.php
new file mode 100644
index 0000000..2db21e4
--- /dev/null
+++ b/tests/unit/Converter/DataObjectTest.php
@@ -0,0 +1,43 @@
+<?php
+
+namespace Rinsvent\Data2DTO\Tests\Converter;
+
+use Rinsvent\Data2DTO\Data2DtoConverter;
+use Rinsvent\Data2DTO\Tests\unit\Converter\fixtures\FillTest\Bar;
+use Rinsvent\Data2DTO\Tests\unit\Converter\fixtures\FillTest\BuyRequest;
+use Rinsvent\Data2DTO\Tests\unit\Converter\fixtures\FillTest\HelloRequest;
+
+class DataObjectTest extends \Codeception\Test\Unit
+{
+    /**
+     * @var \UnitTester
+     */
+    protected $tester;
+
+    protected function _before()
+    {
+    }
+
+    protected function _after()
+    {
+    }
+
+    // tests
+    public function testSuccessFillRequestData()
+    {
+        $data2DtoConverter = new Data2DtoConverter();
+
+        $buy = new BuyRequest();
+        $buy->phrase = 'Buy buy!!!';
+        $buy->length = 10;
+        $buy->isFirst = true;
+
+        $dto = $data2DtoConverter->convert([
+            'surname' => '   asdf',
+            'buy' => $buy
+        ], new HelloRequest);
+
+        $this->assertInstanceOf(HelloRequest::class, $dto);
+        $this->assertEquals($buy, $dto->buy);
+    }
+}
diff --git a/tests/unit/Converter/fixtures/FillTest/HelloClassTransformersRequest.php b/tests/unit/Converter/fixtures/FillTest/HelloClassTransformersRequest.php
new file mode 100644
index 0000000..b43ceaf
--- /dev/null
+++ b/tests/unit/Converter/fixtures/FillTest/HelloClassTransformersRequest.php
@@ -0,0 +1,12 @@
+<?php
+
+namespace Rinsvent\Data2DTO\Tests\unit\Converter\fixtures\FillTest;
+
+use Rinsvent\Data2DTO\Tests\unit\Converter\fixtures\FillTest\Transformer\ClassData;
+
+#[ClassData]
+class HelloClassTransformersRequest
+{
+    public string $surname;
+    public int $age;
+}
diff --git a/tests/unit/Converter/fixtures/FillTest/HelloClassTransformersRequest2.php b/tests/unit/Converter/fixtures/FillTest/HelloClassTransformersRequest2.php
new file mode 100644
index 0000000..02b3db4
--- /dev/null
+++ b/tests/unit/Converter/fixtures/FillTest/HelloClassTransformersRequest2.php
@@ -0,0 +1,12 @@
+<?php
+
+namespace Rinsvent\Data2DTO\Tests\unit\Converter\fixtures\FillTest;
+
+use Rinsvent\Data2DTO\Tests\unit\Converter\fixtures\FillTest\Transformer\ClassObject;
+
+#[ClassObject]
+class HelloClassTransformersRequest2
+{
+    public string $surname;
+    public int $age;
+}
diff --git a/tests/unit/Converter/fixtures/FillTest/Transformer/ClassData.php b/tests/unit/Converter/fixtures/FillTest/Transformer/ClassData.php
new file mode 100644
index 0000000..becfa61
--- /dev/null
+++ b/tests/unit/Converter/fixtures/FillTest/Transformer/ClassData.php
@@ -0,0 +1,11 @@
+<?php
+
+namespace Rinsvent\Data2DTO\Tests\unit\Converter\fixtures\FillTest\Transformer;
+
+use Rinsvent\Data2DTO\Transformer\Meta;
+
+#[\Attribute]
+class ClassData extends Meta
+{
+
+}
diff --git a/tests/unit/Converter/fixtures/FillTest/Transformer/ClassDataTransformer.php b/tests/unit/Converter/fixtures/FillTest/Transformer/ClassDataTransformer.php
new file mode 100644
index 0000000..5f9795c
--- /dev/null
+++ b/tests/unit/Converter/fixtures/FillTest/Transformer/ClassDataTransformer.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace Rinsvent\Data2DTO\Tests\unit\Converter\fixtures\FillTest\Transformer;
+
+use Rinsvent\Data2DTO\Transformer\Meta;
+use Rinsvent\Data2DTO\Transformer\TransformerInterface;
+
+class ClassDataTransformer implements TransformerInterface
+{
+    /**
+     * @param array|null $data
+     * @param ClassData $meta
+     */
+    public function transform(&$data, Meta $meta): void
+    {
+        if ($data === null) {
+            return;
+        }
+
+        if (isset($data['surname'])) {
+            $data['surname'] = '123454321';
+        }
+    }
+}
diff --git a/tests/unit/Converter/fixtures/FillTest/Transformer/ClassObject.php b/tests/unit/Converter/fixtures/FillTest/Transformer/ClassObject.php
new file mode 100644
index 0000000..7f6990e
--- /dev/null
+++ b/tests/unit/Converter/fixtures/FillTest/Transformer/ClassObject.php
@@ -0,0 +1,11 @@
+<?php
+
+namespace Rinsvent\Data2DTO\Tests\unit\Converter\fixtures\FillTest\Transformer;
+
+use Rinsvent\Data2DTO\Transformer\Meta;
+
+#[\Attribute]
+class ClassObject extends Meta
+{
+
+}
diff --git a/tests/unit/Converter/fixtures/FillTest/Transformer/ClassObjectTransformer.php b/tests/unit/Converter/fixtures/FillTest/Transformer/ClassObjectTransformer.php
new file mode 100644
index 0000000..2eb51ee
--- /dev/null
+++ b/tests/unit/Converter/fixtures/FillTest/Transformer/ClassObjectTransformer.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace Rinsvent\Data2DTO\Tests\unit\Converter\fixtures\FillTest\Transformer;
+
+use Rinsvent\Data2DTO\Tests\unit\Converter\fixtures\FillTest\HelloClassTransformersRequest2;
+use Rinsvent\Data2DTO\Transformer\Meta;
+use Rinsvent\Data2DTO\Transformer\TransformerInterface;
+
+class ClassObjectTransformer implements TransformerInterface
+{
+    /**
+     * @param array|null $data
+     * @param ClassData $meta
+     */
+    public function transform(&$data, Meta $meta): void
+    {
+        if ($data === null) {
+            return;
+        }
+        $object = new HelloClassTransformersRequest2();
+        $object->surname = '98789';
+        $data = $object;
+    }
+}