Testing your code in val town

[stevekrouse]

From @tmcw:

Deno's built-in testing won't work - Deno has a deno test command that runs your script in a different way and basically activates the test code. Without specifying that you're running tests and using the custom CLI, you can't use those tests.
node-tap was a contender but doesn't work with our security boundaries. same for vitest.
Just using assertion libraries works:

import * as mod from "https://deno.land/std@0.209.0/testing/asserts.ts";

mod.assert(true);
But won't give you nice test debugging information.

I think we may need to write our own test framework unless there's another option I'm not seeing.

@saolsen also asked for this recently. Lots of folks have asked for it historically.

[saolsen]

Found one test "framework" that worked pretty well with vals. https://www.val.town/v/saolsen/tiny_jest_example

I also think that some combo of an http-val, https://mochajs.org/ and https://www.npmjs.com/package/mochawesome could also work but I haven't tried it yet.

[stevekrouse]

Very cool!

[stevekrouse]

Discussion spawned by this on Discord: https://discord.com/channels/1020432421243592714/1020432421243592717/1195006780560912475

[stevekrouse]

From @dvdsgl: "I'd love a little test file for each Val"

An idea I had recently is to somehow shove the test(s) for a val into that val's readme: you could have a testing server that returns a badge image with the test results. Fairly complex, but could be abstracted away if we find a good pattern

[dvdsgl]

My favorite testing pattern ever was quickcheck properties inline within a Haskell module. Maybe with decorators I could make some inline jest tests in my Val? Maybe this could be simplest approach?

[stevekrouse]

I like that idea @dvdsgl! In my opinion the question then is when do the tests get run? I think it'd be fun to have the test results appear in the markdown in a dynamic image.

@jxnblk just built a test utility badge thing! https://www.val.town/v/jxnblk/test

[dvdsgl]

I'd run the test suite when making a new version, and I would only make a new version if all tests pass.

[dvdsgl]

I'd also let me run the tests, and ideally an individual test, by clicking on something.

[nbbaier]

I'd run the test suite when making a new version, and I would only make a new version if all tests pass.

This idea I really like