westy92 / fr-exercise

Fetch Rewards Coding Exercise - Backend Software Engineering

Installation and Configuration

1. Download and install Node.js (LTS recommended).
2. Clone this repository locally. (git clone [e-mail]:westy92/fr-exercise.git)
3. Navigate to this repository and run npm i to install dependencies.
4. Run npm run build to transpile the TypeScript source code into JavaScript.
5. Run node dist/index.js to start the web service. The default port is 3000, but that can be changed by instead running PORT=8080 node dist/index.js with a port of your choosing.

Running Unit Tests

1. Run npm run test to run the unit test suite.

---

Endpoint Documentation

Add a Transaction

Adds a transaction for a specific payer and date.

Endpoint: POST /points/transaction

Body:

(All fields are required)

• payer - the name of the payer
• points - the points value
• timestamp - the timestamp the transaction occurred

Example Request Body:

{
    "payer": "DANNON",
    "points": 1000,
    "timestamp": "2020-11-02T14:00:00Z"
}

Example Response Body:

(none)

Notes:

• points cannot be 0.
• A user's total points cannot go negative.

Possible Responses:

Status Code	Error Message
201 (Created)	(none)
400 (Bad Request)	Points cannot be zero.
400 (Bad Request)	User points cannot go negative.

---

Spend Points

Spend a user's points. The user's oldest points are deducted first.

Endpoint: POST /points/spend

Body:

(All fields are required)

• points - the points value

Example Request Body:

{
    "points": 5000
}

The corresponding points that are deducted from each payer are returned.

Example Response Body:

[
    {
        "payer": "DANNON",
        "points": -100
    },
    {
        "payer": "UNILEVER",
        "points": -200
    },
    {
        "payer": "MILLER COORS",
        "points": -4700
    },
]

Notes:

• points to spend must be greater than 0.
• A user's total points cannot go negative.

Possible Responses:

Status Code	Error Message
200 (Ok)	(none)
400 (Bad Request)	Points must be positive.
400 (Bad Request)	Not enough points available.

---

Get the User's Points Balances

Gets the user's points balances, separated by payer.

Endpoint: GET /points/balances

Body: Example Response Body:

{
    "DANNON": 1000,
    "UNILEVER": 0,
    "MILLER COORS": 5300
}

Possible Responses:

Status Code	Error Message
200 (Ok)	(none)

---

Clear All User Data

Since the database and cache are in-memory, this endpoint provides an easy way to clear them for testing purposes. This endpoint should be removed once an actual database and cache are added. This endpoint should not be exposed in production.

Endpoint: DELETE /points/clear

Body: There is no request or response body.

Possible Responses:

Status Code	Error Message
200 (Ok)	(none)

---

Suggested Improvements

• Add additional unit tests to test more complex scenarios and increase code coverage.
• Set up a continuous integration environment like GitHub Actions.
• Add input validation. Ensure points are integers, fields aren't missing, etc.
• Use an actual database and cache instead of application memory. Possible options are PostgreSQL and Redis, respectively.
• Add logging throughout the application. (winston is a popular choice.)
• Add user authentication and keep track of points on a per-user basis.
• Add rate limiting.
• Containerize this app with a Dockerfile, using node:18-alpine.