Sokil\Mongo\DocumentTest::testUnsetField_ExistedDocument PHP Method

    public function testUnsetField_ExistedDocument()
    {
        $document = $this->collection->createDocument(array('field' => 'value'))->save();
        $this->assertEquals('value', $document->field);
        unset($document->field);
        $document->save();
        $this->assertEquals(null, $document->field);
        // reload from db
        $document->refresh();
        $this->assertEquals(null, $document->field);
    }