Allow multiple instances registering

[darkgl0w]

Address and close #28 (comment)

No breaking changes were introduced with this PR and the external client behavior has been extended to the named instances.

Checklist

• run npm run test
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows Code of conduct

[mcollina]

LGTM

[Eomm]

Nice feature!

I would add only one more test as solidity check since some user could have already registered multiple redis in different scopes:

fastify.register(function (instance, options, next) {
  // register one redis without namespace
  next()
})

fastify.register(function (instance, options, next) {
  // register two redis with namespace
  next()
})

[darkgl0w]

Hi @Eomm ^^
I implemented one more check to prevent the behavior you described (as it may be considered a bad practice :d) and I made the plugin throw an error. I also updated the documentation to point out the fact that this new feature implies to namespace all the registered instances of fastify-redis.

Also it's to be noted that using this feature won't be a breaking change (at least not really a breaking change) but it requires a little bit of refactoring on existing projects if someone wants to use it. ^^

[delvedor]

LGTM

[darkgl0w]

Applied all the necessary changes and corrected the faulty test.