The Boston Diaries

The ongoing saga of a programmer who doesn't live in Boston, nor does he even like Boston, but yet named his weblog/journal “The Boston Diaries.”

Go figure.

Wednesday, July 07, 2021

To unit test or not to unit test, that is the question

There are two parts of your code. Code that can be unit tested and code that can't be unit tested.

Code that can't be unit tested is simple. Any code that has to touch IO can't be unit tested. Period. Any code that doesn't touch IO can be unit tested. It's that simple.

Keep ALL IO segregated from the rest of your code. Keep IO functions and methods super small. Do not inject IO polluted objects into other parts of your code.

Nothing should ever be mocked. Period. If you don't agree you likely don't under... | Hacker News

In hindsight, this is obvious. The issue I have with unit testing projects like “Project: Lumbergh,” “Project: Sippy-Cup” or “Project: Cleese” is that they're nearly all IO with very little logic (with the caveat that “Project: Lumbergh” implements all the business logic interspaced with IO).

With that said, even though the author also stated not to mock at all, I do. We have a few network services that “Project: Lumbergh” relies upon, and I have written my own versions of those services that basically respond with a canned answer for a particular query. It was easy since the services speak a common protocol (DNS in this case) and I don't have to implement the logic of those services to determine the answer.

I also decided to implement a new regression test and keep the one I have working as a separate test. This way, it'll be easier to implement tests like “data source B replies, data source A times out.” I'm also keeping each test in its own file, so adding new ones should be way easier and hopefully, we won't end up with another 16,000 tests.


Discussions about this entry

Obligatory Picture

[The future's so bright, I gotta wear shades]

Obligatory Contact Info

Obligatory Feeds

Obligatory Links

Obligatory Miscellaneous

You have my permission to link freely to any entry here. Go ahead, I won't bite. I promise.

The dates are the permanent links to that day's entries (or entry, if there is only one entry). The titles are the permanent links to that entry only. The format for the links are simple: Start with the base link for this site: https://boston.conman.org/, then add the date you are interested in, say 2000/08/01, so that would make the final URL:

https://boston.conman.org/2000/08/01

You can also specify the entire month by leaving off the day portion. You can even select an arbitrary portion of time.

You may also note subtle shading of the links and that's intentional: the “closer” the link is (relative to the page) the “brighter” it appears. It's an experiment in using color shading to denote the distance a link is from here. If you don't notice it, don't worry; it's not all that important.

It is assumed that every brand name, slogan, corporate name, symbol, design element, et cetera mentioned in these pages is a protected and/or trademarked entity, the sole property of its owner(s), and acknowledgement of this status is implied.

Copyright © 1999-2024 by Sean Conner. All Rights Reserved.