BinarySearchTree can't remove a root node correctly

[hifizz]

In the test file BinarySearchTree.test.js add a test as below:

it('should remove root node correctly', () => {
    const bst = new BinarySearchTree();
    bst.insert(1).insert(2);
    expect(bst.toString()).toBe('1,2');
    bst.remove(1);
    bst.remove(2);
    expect(bst.toString()).toBe('');
    bst.insert(5);
    expect(bst.toString()).toBe('5');
});

It will report an error:

    Expected: "5"
    Received: ",5"

      15 |     expect(bst.toString()).toBe('');
      16 |     bst.insert(5);
    > 17 |     expect(bst.toString()).toBe('5');
         |                            ^
      18 |   });
      19 | });
      20 | 

Before bst.insert(5) bst is:

      BinarySearchTree {
        root: 
         BinarySearchTreeNode {
           left: null,
           right: null,
           parent: null,
           value: undefined,
           meta: HashTable { buckets: [Array], keys: {} },
           nodeComparator: Comparator { compare: [Function: defaultCompareFunction] },
           compareFunction: undefined,
           nodeValueComparator: Comparator { compare: [Function: defaultCompareFunction] } },
        nodeComparator: Comparator { compare: [Function: defaultCompareFunction] } }

after that, bst is:

      BinarySearchTree {
        root: 
         BinarySearchTreeNode {
           left: null,
           right: 
            BinarySearchTreeNode {
              left: null,
              right: null,
              parent: [Circular],
              value: 5,
              meta: [Object],
              nodeComparator: [Object],
              compareFunction: undefined,
              nodeValueComparator: [Object] },
           parent: null,
           value: undefined,
           meta: HashTable { buckets: [Array], keys: {} },
           nodeComparator: Comparator { compare: [Function: defaultCompareFunction] },
           compareFunction: undefined,
           nodeValueComparator: Comparator { compare: [Function: defaultCompareFunction] } },
        nodeComparator: Comparator { compare: [Function: defaultCompareFunction] } }

This looks like a bug in design, we should remove the node rather than just set the node value to be undefined.

[pbrahmbhatt3]

Can I work on it? @hifizz

[nikhilskul7]

Can i work on this?@hifizz

[hifizz]

Can i work on this?@hifizz

Sure