Error with rails-controller-testing and assert_template

[eLod]

assert_template tries to create a failure message and (Jbuilder) errors ("Failed to add 'inspect' property ..."), because it tries to inspect the Jbuilder (rails-controller-testing tracks locals, JbuilderTemplate passes json: self into sub-renders, like partials).

The problematic line in rails-controller-testing is https://github.com/rails/rails-controller-testing/blob/21014e48be124dd8d0af250b79f682519d445015/lib/rails/controller/testing/template_assertions.rb#L166, specifically the @_rendered_views.locals_for(view) (that returns an array, e.g. [BasicObject.new].to_s raises the same problem).

I understand Jbuilder tries to define as few methods as it must (and hence uses BasicObject), but i feel inspect is very specific to ruby, so it may not be a problem, in that case i'm happy to create a PR.