Refactoring suggestions

[FluorescentHallucinogen]

Idea: find similar things and suggest refactorings. Is it possible?

E.g. find similar types and suggest to extract them into interface, find similar sets of fields in operations and suggest to extract them into fragments, find similar input values and suggest to extract them into variables.

Or vice versa: find fragments and variables that used only in one place and suggest to inline them.

[dotansimha]

This sounds very interesting. Any idea how can we locate those in a robust way what won't create incorrect results?
We can find similar selection sets (with TypeInfo) and suggest on moving to fragments, but that might not fit all use-cases...

[ilyavolodin]

ESlint has a feature for this: https://eslint.org/docs/developer-guide/working-with-rules#providing-suggestions
Suggestions are not fixes, they will not be applied automatically, but will require the user to take an action to apply them. It was added specifically for the cases where there's no way to be sure that automatic change will make sense to the end user.

Finding duplicate code, however, is an np-complete problem, that's not trivial to implement even with a low guarantee.

[FluorescentHallucinogen]

Some of them already implemented in GraphQL Altair: altair-graphql/altair#745 (comment).

[ilyavolodin]

One other thing to keep in mind: ESLint operates on one file at a time, so if you have duplicate code across multiple files, ESLint will not be able to handle that, it will only be able to make a suggestion if it sees duplicate code in the same file.

[dimaMachina]

no-one-place-fragments will be included in next release 3.14.0 to catch

find fragments that are used only in one place and suggest inline them.