Is random in test always bad?

sample.php

<?php 

class Demo
{
    protected $Property;

    public function getProperty()
    {
        return $this->Property;
    }

    public function setProperty($Value)
    {
        $this->Property = $Value;
    }
    
}

class DemoTest extends TestCase
{
    public function setUp()
    {
        $this->demo = new Demo();
    }
    
    public function testInvalidProperty() {
        try {
            $this->demo->setProperty(null);
        } catch (\DomainException $e) {
            return;
        }
        
        $this->throw('Demo property can not be set to null');
    }
    
    public function testProperty()
    {
        $this->demo->setProperty("demo_property");

        $this->assertProperty($this->demo, "demo_property");  
    }
    
    public function testComplicatedProperty()
    {
        $this->demo->setProperty(array('hello' => 'world'));
        
        $this->assertProperty($this->demo, array('hello' => 'world'));
    }
    
    private function assertProperty($demo, $expected) {
        $this->assertEquals($demo->getProperty(), $expected);
    }
}