birthdate = null; $this->assertNull($kid->getAge()); } public function testGetAgeWithBirthdateSet() { $dateFiveYearsAgo = Carbon::now()->subYears(5); $kid = new Kid; $kid->birthdate = $dateFiveYearsAgo; $this->assertEquals( 5, $kid->getAge() ); } public function testGetFirstnameReturnsNullWhenUndefined() { $kid = new Kid; $this->assertNull($kid->getFirstName()); } public function testGetFirstnameReturnsNameWhenDefined() { $kid = new Kid; $kid->first_name = 'Peter'; $this->assertEquals( 'Peter', $kid->getFirstName() ); } }