Software Engineer Task

At Plum, we have a lot of services that need to work together to deliver our product. Many of these services talk to third-party providers to perform their operations – for example moving money, performing background checks, sending messages or emails, etc.

In a lot of cases - due to business, compliance or technical reasons - we need to support multiple third-party providers for the same operation, some of which have wildy different specifications, ranging from simple REST APIs to SOAP.

To maintain our sanity, we abstract these third-parties behind interfaces and expose consistent APIs for the rest of the system to consume. Each service should be able to pick sensible defaults (and fallbacks, if, for example, a provider is unavailable) or allow the consumer to specify the provider if they wish to do so.

Mission

Your mission, should you choose to accept it, is to build a microservice called shorty, which supports two URL shortening providers: bit.ly and tinyurl.com. You don't need to actually sign up to these providers, just implement their API. The service exposes a single endpoint: POST /shortlinks. The endpoint should receive JSON with the following schema:

param	type	required	description
url	string	Y	The URL to shorten
provider	string	N	The provider to use for shortening

The response should be a Shortlink resource containing:

param	type	required	description
url	string	Y	The original URL
link	string	Y	The shortened link

For example:

{
    "url": "https://example.com",
    "link": "https://bit.ly/8h1bka"
}

You are free to decide how to pick between the providers if one is not requested and what your fallback strategy is in case your primary choice fails. Your endpoint needs to return a JSON response with a sensible HTTP status in case of errors or failures.

What you need to do

Create a Python env (using Python 3.6+) and install the requirements.
Build the POST /shortlinks endpoint. We've provided a skeleton API using flask.
Write some tests. We've provided a test blueprint using pytest.

Deliverable

You should deliver your solution as a Pull Request in your repo. Document your design choices and anything else you think we need to know in the PR description.

What we look for

In a nutshell, we're looking for tidy, production-quality code, a scalable design and sensible tests (unit tests, integration tests or both?). Imagine that your code will be read by other developers in your team – keep them happy :-)

Resources

Flask: http://flask.pocoo.org/
pytest: http://pytest.org/latest/
virtualenvwrapper: https://virtualenvwrapper.readthedocs.io/en/latest/
HTTP statuses: https://httpstatuses.com/

Disclaimer

We will not use any of this code for any of Plum's applications.