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• I havesearched for related issues and found none that match my proposal.
• I have searched thecurrent rule list and found no rules that match my proposal.
• I haveread the FAQ and my problem is not listed.

Relevant Package

rule-tester

My proposal is suitable for this project

• I believe my proposal would be useful to the broader TypeScript community (meaning it is not a niche proposal).

Description

From#8211: there are quite a few enhancements to the ESLint RuleTester that we'll need to reflect in our ownrule-tester class.

• Rule Tester checks for missing placeholder data in the message
• Stricter rule test validations
• detect duplicate test cases
• check for parsing errors in suggestion fixes
• assert suggestion messages are unique in rule testers

Per the discussion in that thread, we'd like to not treat this as a breaking change:

TBH I'm actually okay with us updating @typescript-eslint/rule-tester with these changes. Yes it will cause errors in tests for people - but they're all correct errors that should have been caught previously. I think it's okay treating itthe same as a lint rule i.e. "A change to the plugins shall not be considered breaking if it: ... Adds additional checks to an existing rule that causes new reports in a small-to-medium set of cases in an average codebase".

...so unless someone protests, we'll merge this into themain branch rather thanv8.

Additional Info

Adding to thev8 milestone as it's required for ESLint 9 support, even though we'd like to land this sooner.

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