Katkat
Back

Process auth requests with fraud rules

StripeSoftware Engineer · Technical Screen
MediumSoftware EngineerTechnical ScreenCoding & Algorithms

Last updated

This question evaluates a candidate's ability to implement stateful stream processing and event handling, including applying time-scoped fraud rules to authorization requests, maintaining chronological ordering, and producing verified outputs via unit tests.

Question

Implement a function that, given a list of Authorization Requests (timestamp_seconds, unique_id, amount, card_number, merchant), outputs a human-readable report ordered chronologically, with each line formatted as "timestamp unique_id amount APPROVE".

Extend the function to also consume a stream of Fraud Rules (time, field, value). From the rule’s time onward, any future Authorization Request whose specified field equals the rule’s value must be marked fraudulent. Produce the same report, but with "REJECT" for fraudulent requests and "APPROVE" otherwise. Include unit tests demonstrating correctness.