Update: Allow testing Suggestions with data in RuleTester (fixes #12606)

[mdjermanovic]

What is the purpose of this pull request? (put an "X" next to item)

[X] Add something to the core

fixes #12606

What changes did you make? (Give an overview)

RuleTester now allows testing Suggestions with data.

Example:

{
    code: "var foo;",
    errors: [{
        suggestions: [{
            messageId: "renameFoo",
            data: { newName: "bar" },
            output: "var bar;"
        }, {
            messageId: "renameFoo",
            data: { newName: "baz" },
            output: "var baz;"
        }]
    }]
}

Also, RuleTester documentation was missing messageId and data for errors.

Is there anything you'd like reviewers to focus on?

To avoid breaking change, as noted in #12606 (comment), it's still allowed to specify both desc and messageId for the same suggestion. This combination is now removed from the example in the docs, but it still works and both values would be tested.

Also, there are still some differences when compared to what can be used in error tests. This would probably require additional discussion and it seems better to make separate PRs (if needed):

• suggestions cannot be a number, e.g., suggestions: 2 to just test that there are 2 suggestions and nothing more. A workaround is suggestions: [{}, {}].
• A suggestion as an element of the suggestions array can't be just a string that would be treated as desc.
• desc can't be a regex.
• there is no check whether the suggestion's fix produces a valid code or a parsing error.
• RuleTester doesn't seem to support suggestions that don't have a fix. This raises a question, is a suggestion that doesn't include a fix allowed by the API?

[ilyavolodin]

• suggestions cannot be a number, e.g., suggestions: 2 to just test that there are 2 suggestions and nothing more. A workaround is suggestions: [{}, {}].

Sounds good to me. There was even talk about removing ints from errors at some point.

• A suggestion as an element of the suggestions array can't be just a string that would be treated as desc.

👍

• desc can't be a regex.

I guess that's fine. Not sure why we need to check for that.

• there is no check whether the suggestion's fix produces a valid code or a parsing error.
  RuleTester doesn't seem to support suggestions that don't have a fix. This raises a question, is a suggestion that doesn't include a fix allowed by the API?

Good question. I think we should not allow suggestions without fixes. The whole point of suggestions is to provide multiple ways of working around a problem. Providing them without code changes doesn't make sense to me.

[nzakas]

LGTM

[kaicataldo]

LGTM, thank you!