Add `getTestPackage` to verify various attributes of packages

[romainmenke]

What is the problem you're trying to solve?

see:

• Encourage using common keywords for plugins, configs, and formatters in documentation stylelint#7857 (review)
• https://github.com/csstools/postcss-plugins/blob/e8809370ba61f406c3063b7a7566faf3223c4aae/packages/postcss-tape/src/index.ts#L98-L141

testRule and testRuleConfigs help people to write rule tests (as the name suggess :D ) but maintaining a good npm package with a Stylelint rule goes beyond writing rules.

For the PostCSS plugins we author under @csstools we found that we make the same mistakes over and over again and that we weren't following the PostCSS guidelines for plugins.

Things we often did wrong:

• name doesn't start with postcss-
• postcss-plugin was missing from keywords
• postcss was not a peer dependency

---

In Stylelint we also have guidelines and docs for writing rules and they contain similar aspects: https://github.com/stylelint/stylelint/blob/main/docs/developer-guide/plugins.md#peer-dependencies

What solution would you like to see?

Maybe we can create a getTestPackage function that contains tests for package.json?

This has two benefits:

• it is easier for authors to be consistent
• we can amend the guidelines and use this test as a way to communicate and promote the new guidelines

[Mouvedia]

• keywords based on the type argument
• files is missing a README at the root
• mapping between engines.node and peer dependency version of stylelint
• has either stylelint-test-rule-node or jest-preset-stylelint as a dependency
• rules
  • messages start with either "Unexpected" or "Expected"
  • missing primaryOptionArray
• etc.

[ybiquitous]

@romainmenke Thanks for opening the request. Sounds great. 👍🏼

If the new check works, we should want to port it to stylelint-test-rule-node.

@Mouvedia Thanks for the additional suggestions. They sound good to me. We can include them or start with minimal checks for baby steps. 👍🏼

[ybiquitous]

I've labeled the issue as ready to implement. Please consider contributing if you have time.

If you still have any concerns about starting the work, feel free to comment. We can go back anytime. 😃