Change Request: Add options to rule-tester requiring certain assertions

[ST-DDT]

ESLint version

v9.30.1

What problem do you want to solve?

I try to improve the quality of some (invalid) rule tests, by making sure they all test the same properties.
Specifically I want to ensure, I (and future developers) test for

• individual errors instead of error counts
• and test for specific error messages and locations instead of partial checks

What do you think is the correct solution?

I have considered two similar solutions:

1. Add assertionOptions/options: { requireMessage: boolean; requireLocation: boolean } to RuleTester constructor
2. Add assertionOptions/options: { requireMessage: boolean; requireLocation: boolean; requiredBlocks: Array<'valid', 'invalid'> } to RuleTester's run method

The second option would make it possible to run multiple test runs with the same runner instance but different options.

Participation

• I am willing to submit a pull request for this change.

Additional comments

Requiring the location would require the full location (might be configurable with boolean | 'full')

Continuation of #19904

• feat: output full actual location in rule tester if different #19904

[nzakas]

Thanks for the suggestion. I can see why this would be useful and I think we'd need to gather some feedback to determine the right API and functionality. As such, we should put this change through the RFC process.

[ST-DDT]

Done: eslint/rfcs#137

• feat: add assertion options to RuleTester rfcs#137