Wrong test scenario

JavaScript
1

Tell us what’s happening:
.remove method is called only once for deleting from an empty list. While two last suites (The first item should be removable from the list. The last item should be removable from the list.) definitely require it, not only .add

Your code so far


var Node = function(data, prev) {
this.data = data;
this.prev = prev;
this.next = null;
};
var DoublyLinkedList = function() {
console.log({created: true})
this.head = null;
this.tail = null;
// Only change code below this line
Object.assign(this, {
  length: 0,
  add: function(el) {     
    console.log({add: el, length: this.length})   
    this.length += 1 
    
    if (this.length === 1) {
      const node = new Node(el)
      this.head = node
      this.tail = node
      return node
    } else {
      const node = new Node(el, tail)
      tail.next = node
      tail = node
      return node
    }
  },
  remove: function (el) {
    const {length} = this
    console.log({remove: el, length})   
    if (length === 0)
      return null

    let pre = null
    , {head: pointer} = this

    while (pointer !== null) {
      if (pointer.data !== el) {
        pre = pointer
      } else {
        this.length -= 1
        const {next} = pointer
        if (pre === null) {
          this.head = next
          next.prev = undefined
        } else {
          next.prev = pre
          pre.next = next
        }
      }
      
      pointer = pointer.next
    }
  }
})
// Only change code above this line
};

Your browser information:

User Agent is: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:81.0) Gecko/20100101 Firefox/81.0.

Challenge: Create a Doubly Linked List

Link to the challenge:

2