fix issue with using draper outside of controller/view context

[timdiggins]

Description

Replace ActionController::TestRequest with ActionDispatch::TestRequest

because

1. soft deprecated
2. will cause very hard to predict/test failures with ActiveJob/Sidekiq/Rake tasks. see issue with using draper outside of controller/view context within a rake task or (active)job #926

The current PR also drops support for rails < 6.0
I think this is a good idea (especially as the tests that were dropped were written from a Rails 5.0 perspective, so are very outdated, and brittle) but open to discussion around this if there's any engagement on this PR.

Testing

See #926

To-Dos

• tests: I have not done additional tests to prove the need for the PR as they are hard to implement and harder to maintain and wouldn't catch regressions in any case.
• documentation: unnecessary I think

References

• GitHub Issue 926

fixes #926

[tovodeverett]

I have no authority at all with Draper, so I'm sorry that I can't help with getting your PR approved.

I do have one comment - I found the first line of the Description to be rather confusing.

You wrote: "Replace ActionController::TestRequest with ActionController::TestRequest"
I think you may have meant to write, "Replace ActionController::TestRequest with ActionDispatch::TestRequest"

[mdudzinski]

I can confirm this PR fixed the problem (that popped up after upgrading to rails 6.1) in my project.

In my case it was:

NoMethodError: undefined method `parameters' for nil:NilClass

@_params ||= Parameters.new(request.parameters)

~/.gem/ruby/3.1.4/gems/actionpack-6.1.7.7/lib/action_controller/metal/strong_parameters.rb:1187:in `params'

Thank you @timdiggins !