Snyk Recursive npm Exercise

This is my solution to the Snyk python recursive npm PR review exercise. I have included comments around any logic that I have changed. It is worth noting that the biggest issue on the original PR is that there is no caching. Therefore, dependencies will require multiple npm look-ups in the original state. I have cached at both the get_dependencies() and get_package() methods in order to improve performance. Caching has been done with redis rather than a simple hash table, this was so that we can clear the cache independently of runtime as well as setting an expiry to flush the cache. This method is ideal as packages will occasionally be updated and it should keep them in-line with the current npm registry.

The other issue was that in the original PR the format uses the npm package name as a key. This is not advisable as it makes it near impossible to query the response data when the key is dynamic.

Other than the above, the issues are simply detecting when the response from the npm registry does not include a description, as well as determining when you're visiting a circular dependency. An example of this can be seen here with reference to the npm package d. Without this check you will run into a maximum recursion depth exceeded error, as it will keep iterating over a collection of the same packages.

If you're looking for a package to stress test use largest-package -> https://www.npmjs.com/package/largest-package

Prerequisites

• Python 3.9

Getting Started

To install dependencies and start the server in development mode:

brew install redis
brew services start redis

pip install poetry
poetry install
python src/app.py

The server will now be running on an available port (defaulting to 3000) and will restart on changes to the src files.

Then we can try the /package endpoint. Here is an example that uses curl and jq, but feel free to use any client.

curl -s http://localhost:3000/package/react/16.13.0 | jq .

Most of the code is boilerplate; the logic for the /package endpoint can be found in src/package.py, and some basic tests in test/test_package.py

You can run the tests with:

pytest