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Last active Mar 10, 2022
What would you like to do?


Let's get all your subordinates.


  1. One user can have only 1 role, as the given data structure.
  2. RoleIds and UserIds are unique.

Solution formulation

Steps I thought of and executed for solving the get subordinates for given user:

  1. Get user by user id from list of users
  2. Get all child roles of the given users' role
    1. Nest roles for the given role to get a tree of roles
    2. Get all descendent role ids for all children of given role
  3. Get all users that have the roles from step 2

Step 2 has the main logic in my solution, it can be found in the role repository.

Libraries/Tools used

  • No main dependency. It might have been easier/less code to do this with something like Lodash, but that would defeat the purpose of the coding task.
  • Written in node with some ES6 syntax. tested on Node v12.13.1
  • Uses Jest for testing

How to setup

Run the following commands to setup, given node and npm is available:

  1. git clone
  2. cd subordinater
  3. npm install
  4. node index.js -> to see a test output

Running tests

  • To run the tests run npm t or jest on the project root.
  • For code coverage run npm run test:cov , coverage files will be in the coverage folder.

The current coverage is 100%.

Code Coverage

Decisions and tradeoffs

  1. Basic require is chosen in place of ES6 imports and class keyword for ease.
  2. I have chosen more of a functional/procedural path with more pure functions than object oriented pattern. I think it is better in this small problem space than trying to model or use a design pattern like composition design pattern where a user will have a role object.
  3. Setting users and roles as class variable (this.roles) can be one fast way to encapsulate the data. I was focused more on getting the result and testing the code with a high code coverage.
  4. There are places to improve. Still, I would not opt to do them all for a small problem domain like this one. As software engineers we need to find a balance.

If it was a bigger project

This is a coding challenge and scope is quite small. If it was a bigger real project, doing the following would be better:

  1. More focus on architecture and software design would be necesssary. For a solution of ~80 lines it would be over optimization IMHO.
  2. Choosing typescript or using some validator like validator or Joi for validation would be better.
  3. If a RDBMS is used, it would be easier to solve this with a relational database and a select SQL than on the code.
  4. It would be great to have some mutation testing in place like Stryker to know how effective the tests are in addition to the coverage.
  5. For a team project, it will be good to have the project dockerized.
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