Add testRuleConfigs function

[ybiquitous]

Which issue, if any, is this issue related to?

Ref stylelint/stylelint#7124

Is there anything in the PR that needs further explanation?

This change adds a new schema property to test an invalid rule configuration.

Usage:

testRule({
	ruleName,
	config: ['number'],
	invalidConfig: ['foo'],
	accept: [/*...*/],
	reject: [/*...*/],
});

---

This PR adds a new global function testInvalidRuleConfigs to test invalid rule configs.

Usage:

testInvalidRuleConfigs({
  plugins: ["."],
  ruleName,

  accept: [
    {
      config: "valid"
    }
  ],

  reject: [
    {
      config: "invalid"
    },
    {
      config: [/invalid/],
      description: "regex is not allowed"
    }
  ]
});

Output:

$ npx jest --verbose
 PASS  __tests__/getTestRuleConfigs.test.js
  plugin/foo configs
    accept
      ✓ 'a' (32 ms)
      ✓ string is allowed (1 ms)
    reject
      ✓ 123 (1 ms)
      ✓ regex is not allowed (1 ms)

 PASS  __tests__/getTestRule.test.js
  plugin/foo
    accept
      [ '.a' ]
        '.a {}'
          ✓ no description (19 ms)
          ✓ with description (1 ms)
    reject
      [ '.a' ]
        '#a {}'
          ✓ no description (1 ms)
          ✓ with description (1 ms)

[jeddy3]

It feels useful to test invalid configs but a little counterintuitive to do so in testRule.

We created testRule to make it easier to check that a rule was correctly reporting problems against snippets of CSS—the schema properties like config, customSyntax, fix, ruleName, and so on set up a run for the tests in accept and reject.

A invalidConfig schema property feels out of place as it doesn't fit in either of these categories, i.e. it's not setting up a run nor testing against CSS.

I wonder if we can find a better home for it. Perhaps we can add another function to the preset, e.g. testInvalidRuleConfigs which has a simpler schema designed around testing multiple invalid configs:

testInvalidRuleConfigs({
  plugins: ["."],
  ruleName,
  configs: [
    {
      "config": ['foo'],
      "description": "a single string" // optional description if needed
    },
    {
      "config": [21312]
    }
  ]
})

[ybiquitous]

@jeddy3 Thanks for the great feedback! I agree with your suggestion, so I'll rewrite the code to create a new function. 👍🏼

[jeddy3]

Thank you for making the changes!

It feels more intuitive as a separate function.

I've added one comment.

[jeddy3]

LGTM, thank you for making all the changes!

[ybiquitous]

Thanks, too. I appreciate your helpful advice. 😄

I'll release the next version 6.2.0 after merging this PR!

[ybiquitous]

https://github.com/stylelint/jest-preset-stylelint/releases/tag/6.2.0 released! 🎉