setIP( '1.2.3.4' ); $derivative = new DerivativeRequest( $original, [] ); $this->assertEquals( '1.2.3.4', $derivative->getIP() ); $derivative->setIP( '5.6.7.8' ); $this->assertEquals( '5.6.7.8', $derivative->getIP() ); $this->assertEquals( '1.2.3.4', $original->getIP() ); } }