Thanks for taking the time to check out our backend engineering challenge! Today, you'll be building a command-line tool called msr. Please implement your CLI in Python, and ensure that, once installed (with a standard pip install), it can be called simply by typing msr at a shell prompt.

The project has a 3 hour time limit; we've designed it to be completable in 1-2 hours. It might be helpful to start by getting something working, and then cleaning it up. Done is better than perfect for a first pass!

You've been tasked with putting together a CLI that performs various measurements on remote web pages. We'll call this CLI msr. There will be several subcommands to msr, each of which might take some arguments.

We've provided a script (test.sh) that you can run to test your implementation.

Note that the tests should not take a long time to run. If your implementation takes more than 30 or so seconds, you should consider making some of your serial requests parallel.

The first subcommand to implement is version. Calling msr version should print a semver string to STDOUT.

msr register should take one argument, a URL. It should validate this URL, and return with a non-zero exit code if the URL is invalid. If the URL is valid, it should add the URL to an internal, persistent registry.

Feel free to use a file to back this registry, although proper XDG conventions (e.g. XDG_CONFIG_HOME) should be followed.

msr measure takes no arguments, and should return a pretty-printed table of all of the URLs in the registry, along with the size (in bytes) of the body received by making a GET request to that URL. The implementation should follow redirects as necessary to get an actual content body.

msr race takes no arguments, and should return a pretty-printed table of all the domains found in the URLs in the registry, along with the average page load time for the URLs of that domain.

Once you get everything else working, test.sh includes one last testing method that is intended to see how your implementation holds up when the registry has a bunch of URLs in it. blast registers all the URLs in the pre-seeded blast.txt file, and then calls race. How fast can you make this run?

You should have received an email from Sym with a link to upload your submission. If you haven't, please let us know!