模拟参数传递给函数

Question

我在测试时遇到同样的问题

 public function testReturnUser(){
        $faker = Factory::create();
        $user = new User($faker->userName, $faker->email);

        $mockFinder = \Mockery::mock(ClassFinder::class);
        $mockFinder->shouldReceive('find')
            ->with(User::class, 1)
            ->andReturn($user);
        $helper = new Helper($mockFinder);
        $this->assertEquals([$user], $helper->getMethod(User::class));
    }

并在Helper类中

class Helper {
   private $finder;
   public function __constructor(ClassFinder $finder){
      $this->finder = $finder;
   }
   public function getMethod(string $className, array $data =[]){
      return $this->finder->find($className, $data['id']);
   }
}

所以问题是，当我在没有第二个可选参数的情况下调用getMethod并运行测试时，我发现$data['id']是无效索引， 虽然我将参数传递给了模拟对象。那么，如果有人知道为什么会这样？