Add tests for remark plugin(s)

[SilasBerger]

Add tests for all currently implemented remark plugins, following the unified() usage as described here.

This is not entirely trivial, because (a) the transformed result is not returned from the unified() call but passed as an input to a callback function, and (b) Jest seems to run into a TypeScript-related issue with unified (see error below).

Test suite failed to run

    Jest encountered an unexpected token

    Jest failed to parse a file. This happens e.g. when your code or its dependencies use non-standard JavaScript syntax, or when Jest is not configured to support such syntax.

    Out of the box Jest supports Babel, which will be used to transform your files into valid JS based on your Babel configuration.

    By default "node_modules" folder is ignored by transformers.

    Here's what you can do:
     • If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/ecmascript-modules for how to enable it.
     • If you are trying to use TypeScript, see https://jestjs.io/docs/getting-started#using-typescript
     • To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config.
     • If you need a custom transformation specify a "transform" option in your config.
     • If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option.

    You'll find more details and examples of these config options in the docs:
    https://jestjs.io/docs/configuration
    For information about custom transformations, see:
    https://jestjs.io/docs/code-transformation

    Details:

    /Users/silas/repos/teaching-website/node_modules/unified/index.js:2
    export {unified} from './lib/index.js'
    ^^^^^^

[lebalz]

i use vitest - i like the idea of sharing our plugin infra and i'm open to use another test setup... for the given usecase i was satisfied with vitest... example test: https://github.com/lebalz/ofi-blog/blob/docusaurus-v3/src/plugins/remark-deflist/tests/plugin.test.ts

[SilasBerger]

https://github.com/lebalz/ofi-blog/blob/docusaurus-v3/src/plugins/remark-deflist/tests/plugin.test.ts

Perfect, I'll check that out! I'm not super set on Jest, it was just my default choice.

[lebalz]

Ok cool - normally i go with jest too, but with the missing esm support of jest i was afraid it would be a config-inferno:

If you write unit tests for your plugins, you must know that Jest does not support ESM. You can either use a tool that supports ESM, or vendor the dependencies you use as CJS.

Vendoring many small packages to get Jest to work is super annoying to do but it works, and is it what Docusaurus does...

from https://github.com/facebook/docusaurus/discussions/9337