public function testAdd() { $objNumber = new Number(50000); $objNumberToAdd = new Number(120000); $objNew = $objNumber->add($objNumberToAdd); $this->assertSame(50000, $objNumber->getAmount()); $this->assertSame(120000, $objNumberToAdd->getAmount()); $this->assertSame(170000, $objNew->getAmount()); }