Rails 6 Support

[pacso]

Description

The current gemspec restricts Draper to Rails versions no higher than 5.x.

This change to the gemspec allows any versions including or greater than 5.x, and as such allows Draper to be used with Rails 6.

I'm using this branch against an actively developed project which we're now developing against Rails 6 with no issues so far.

Testing

Existing tests should suffice as there are no changes in Rails 6 which should affect Draper.

[codebycliff]

Thanks for this! Sorry I took so long to get around to it.

[varyonic]

@codebycliff rake release?

[codebycliff]

@varyonic I will try to get a release cut this weekend. I was holding off as I have been testing #845 on a couple of our applications to make sure there aren't any major issues.

[jrochkind]

Is Draper currently being tested against Rails 6? I don't see any Rails versions switches in .travis.yml, so I'm guessing it maybe just gets tested by the latest version bundler will install... which is probably not the Rails 6.0.0 rc, since bundler wont' install pre-releases unless specifically mentioned in a Gemfile etc.

Would it make sense to test against the Rails 6 RC to prepare for Rails 6? That could be done manually, just to see if it passes, fairly easily... getting it to be done by travis would, I guess, require setup for testing multiple Rails versions under travis, which is non-trivial.

Thoughts? In general on how confident we are that Draper is ready for Rails 6?

[jrochkind]

Also, I see that the requirements in this PR are '>= 5.0'. (I also see there has not been a draper release with this change yet).

That is probably not optimal, because we can't promise that it will work with Rails 6.1 or some future Rails 7. But once a draper is released that says '>= 5.0', in the far future when Rails 7 or 8 exists, bundler will be willing to use that past version that says '>= 5.0' when resolving with a Rails 7 or 8.

It would probably be better to say '>= 5.0', '< 6.1' maybe?

[pacso]

In general on how confident we are that Draper is ready for Rails 6?

I'm using it in a Rails 6 app without any issues.

[jrochkind]

@pacso thanks! While this particular commit doesn't seem to be included in a release, latest Draper 3.1.0 does seem to allow any >= 5.0, so I guess you can use with Rails 6 rc with Draper 3.1.0? OK, cool.