Detect single-use shared_{context,examples} (or other setup?)

[dgollahon]

After reading rubocop/rubocop#6786 (comment), it occurred to me that rspectre could also count single-use setup. For lets or similar this might be slightly aggressive (but maybe worth an optional flag), but it's almost certainly helpful for shared_* tools. Inlining is almost always better when something is used ones.

[jaynetics]

I think both would be nice to have. I'd argue that even for shared_*, it should only happen when passing a flag, though.

Right now rspectre is a zero config tool that finds/removes clearly wrong things, and that makes it refreshingly straightforward to use and to convince people of "accepting" its suggestions, compared to e.g. rubocop.

A shared example might also be created on purpose for the first use case if more use cases are very likely to come up in the future.

[bquorning]

An option to detect single-use lets (and let me turn them into local variables) would be neat.