alexsmaldone/fetch-takehome-personal-redo

Fetch Rewards Backend Software Engineering Takehome

A REST API designed to receive HTTP requests and return responses based on a user's transactions, reward points balance, and reward points spend.

Overview

• A user can have reward points balances in their account from various payers (presumably businesses where a user transacts)

  • e.g., {"Nike": 500, "Cheesecake Factory": 1000}

• Transactions are submitted to add or subtract points from a user's reward points balance

  • Payer balances in a user's account cannot go below 0

• A user can spend points from their account/payer balances

  • User's total points cannot go below 0
  • Points are spent in First-In-First-Out order based on transaction timestamp, irrespective of payer

Dependencies

• Python - The latest version of Python to run the program, or at least version 3.7+
• FastAPI - A modern, fast, web framework for building APIs with Python 3.6+ based on standard Python type hints
• Pydantic - Data validation and settings management using python type annotations
• Pytest - Python testing framework

Installation

1. Clone git repo to your local machine

    git clone https://github.com/alexsmaldone/fetchrewards-takehome.git
   

2. Cd into the project's root directory

    cd fetchrewards-takehome/
   

3. Install dependencies

    pip install -r requirements.txt
   

4. Start the server

    uvicorn main:app --reload
   

   Your terminal should read: Uvicorn running on http://127.0.0.1:8000

   You can verify the server is running by visiting http://localhost:8000 in your browser, where you should see this response:

   Hi! Welcome to Alex Smaldone's Fetch Rewards Backend Engineer Takehome Test

Using the API

This service uses no database or persistent storage, so user points / payer transactions will reset every time the server is started/restarted

I recommend using a tool like Postman to test out API calls.

POST Route "/points" - Add Payer Transaction

Request Format

{"payer": <str>, "points": <int>, "timestamp": <datetime>}

Example Request and Response

{"payer": "Nike, "points": 500, "timestamp": "2022-06-20T11:07:01.017197"}

{"Message": "Transaction Successful", "Current Balance": 500}

Example Request and Response (including previous)

{"payer": "Adidas, "points": 500, "timestamp": "2022-06-20T11:07:02.017197"}

{"Message": "Transaction Successful", "Current Balance": 1000}

Error Handling

• Preventing payer balances from going negative
• Preventing 0 points transactions
• Type checking for request body values

POST Route "/points/spend" - Spend User Points

Request Format

{"points": <int>}

Example Request and Response

{"points": 250}

Subtracts 250 points from Nike payer balance as it is the oldest transaction.

{"payer": "Nike", "points": -250}

Error Handling

• Preventing spend that is greater than total user points
• Preventing negative spend
• Type checking for request body values

GET Route "/points" - Get User Points by Payer

After making the above transaction and spend requests, the payer points would look like:

{
"Nike": 250, "Adidas": 500
}

Running Tests

You can run the tests in test_main.py from the main directory by running:

pytest

The tests check the following:

• Returns the proper points balance
• Cannot create negative payer balances with a transaction
• Cannot add 0 point transactions
• Tests valid transaction sequences
• Tests valid spend sequences
• Spend must be greater than 0 and less than total available points