Tree Assignment

Background

You are requested to implement a tree data structure which is based on abstract nodes. Each node has zero or more children and zero or one parent. Nodes are created and added as children to their parent nodes in run time. Upon creation each node requests an asynchronous resource, which is supposed to become ready later (in an unpredictable timeframe or order), a callback can be given to the resource in order for the node to be notified about its readiness.

The main challenge of the assignment is telling whether a node (or subtree) is ready. A node is considered ready only when it has its resource ready, and all of its descendants have their resources ready too.

Method

You are given an example Resource class, which becomes ready randomly within 200-1000 ms, and two boilerplate classes: SimpleNode and AsyncNode, to be implemented by you so that it fulfils the requirements in each of the steps.

The steps are based on each other:

1. SimpleNode a synchronous node class
2. AsyncNode an asynchronous node class

Your solution needs to cover at least the methods marked with the comment "implement", you can also add and change whatever you like in these classes, as long as you preserve the existing methods structure. Note that the AsyncNode is derived from SimpleNode in the previous step and should not break any existing functionality.

This assignment should be completed in ​either​ latest Node.js or Python 3.x.

Graph Example

graph TD
A[1] --> B[2]
A --> C[3]
A --> D[4]
B --> E[5]
B --> F[6]

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• If 6 has its resource ready, then 6 is considered ready since it has no children
• If 2 and 6 have their resources ready, 2 isn't considered ready since 5 isn't ready yet
• If 2, 3, and 4 have their resources ready, 1 isn't considered ready since 5 and 6 aren't ready yet

Review Criteria

• Readability and tidiness
• Efficiency
• Passing provided tests

  cd test-js
  npm test
  

  -- or --

  cd test-py
  python3 -m unittest