BST - remove root node error

[JakeHP]

The following test (that doesn't exist in codebase) fails with the current BST remove()

  it('should insert and remove single node properly', function () {
    var bTree = new BinaryTree();
    bTree.insert(15);
    var node = bTree.find(15);
    bTree.remove(node);
    expect(bTree._root).toBe(null);
  });

Here's the issue explained in comments

// this is called in .remove()
this._replaceChild(node._parent, node, null); // node._parent is null since the node is the root, node is valid
..
..
..
   function (parent, oldChild, newChild) {
    if (!parent) { //parent param is null, enter if
      this._root = newChild; //assigns null to root
      this._root._parent = null; // null._parent throws error
    } else {
      if (parent._left === oldChild) {
        parent._left = newChild;
      } else {
        parent._right = newChild;
      }

      if (newChild) {
        newChild._parent = parent;
      }
    }

I've got a fix in place, a bunch of tests for BST, and will submit a PR once #45 clears (changes are on my local master).

[JakeHP]

Fixed as of #47 , closing.