including unit tests

[MatsSundqvist]

I want to be able to include unit tests written in typescript. I succeeded to set up the configuration so that files from 'test' is going into build/test. However all files named "*.test.ts" are excluded.
I found out that this is expected since it's in the default configuration. I tried to set a custom 'exclude' in the snowpack.config.json. But this didn't change anything.
I think that this behavior is due to deep merging the default configuration with my config. The default behavior of deep merge is to merge arrays. Maybe it could be better to replace arrays instead of merging them.

[FredKSchott]

Hey @MatsSundqvist, just to be clear: you're talking about unit tests in your application, and not for the Snowpack repo/codebase itself?

We'll have to think about this a bit, I want to support your use case but I'd also consider this a breaking change, which just means it might be a bit before we're ready to release a v3.0

[MatsSundqvist]

Yes, @FredKSchott I'm talking about unit tests for My applikation I think that's the only remaining issue for me.
Thank you for your great work with snowpack!

[FredKSchott]

Thank you!

In the meantime, you may want to update your tests to a different naming scheme, that Snowpack won't ignore by default. As a reminder, here is what we ignore in your build:

  exclude: ['__tests__/**/*', '**/*.@(spec|test).*'],

Anything else should be good to go!

[MatsSundqvist]

yes that works. Do you have any ideas how to best incorporate front end unit tests in the build?
One way is to use the deno test runner, but I think it could be nice to run it in a headless browser. Using a headless browser, there must be a server up and running to serve the modules I guess.

[drwpow]

Do you have any ideas how to best incorporate front end unit tests in the build?

Because there’s no true ESM-friendly test runner (yet), unit tests are basically impossible. All you can do reliably are end-to-end tests using a headless browser as you described. Deno test runner could work too, but I haven’t tried that!

But also, just my 2¢, but I’ve never really trusted front-end unit tests anyway 🙂. In order for unit tests to be reliable, you have to faithfully reproduce their runtime environment, and that’s impossible to do for front-end code without the browser itself (which I think pushes it out of unit test territory and more into integration/E2E territory). So for that reason, I personally am a big fan of Puppeteer tests, or something like Percy for visual regression testing.

[MatsSundqvist]

thanks for your answer @drwpow
I have tried deno, and it is very easy to use with snowpack output, since it's all ESM with relative imports. Maybe I have a look at puppeteer if I want to go more into integration testing.