This is a solution to the clerq technical challenge implemented in TypeScript & Node.js by Jason Katz.

On a local machine with Node.js & yarn installed, run yarn to install dependencies. To build the project, run yarn build, and to run the server run yarn start. Tests can be run with yarn test.

When the server is started, it will run on port 8080.

There is a liveness endpoint /test to verify that the server is running and accessible via HTTP.

The endpoint to compute the settlement amount for a merchant is GET /merchant/<merchantId>/settlement/<date>, where the date is provided in ISO-8601 format. The endpoint can be hit through curl or any HTTP client.

This implementation involves a retry mechanism around the flakey ACME API to maximize chances that the data is both retrieved properly and that it's valid. An Axios retry mechanism is used for 5xx errors & timeouts from the API, and a separate retry mechanism is used for data validation (circular response & field validation).

The logic to interact with the ACME API is encapsulated in src/acme-api.ts.

The business logic for computing the settlement for a merchant is found in src/settlement.ts, with some logic to request all merchant transactions. This logic includes multiple requests to ACME API in case there are multiple pages of transactions that need to be fetched.

The business logic is unit tested in test/settlement.test.ts using jest.

Due to the time constraint, the response only contains the settlement amount, and nothing else. With additional time, metadata about the merchant and the relevant transactions would have been included in the response. Furthermore, additional automated testing & functionality to list merchants would have been included.