Rails 5 Arbre bug: instance variable not set

[seanlinsley]

undefined method `title' for nil:NilClass (ActionView::Template::Error)
./spec/rails/rails-> 5.x/app/views/admin/posts/review.html.arb:2:in `block in _app_views_admin_posts_review_html_arb___4279224217782219933_148541500'
./spec/rails/rails-> 5.x/app/views/admin/posts/review.html.arb:1:in `new'
./spec/rails/rails-> 5.x/app/views/admin/posts/review.html.arb:1:in `_app_views_admin_posts_review_html_arb___4279224217782219933_148541500'
features/specifying_actions.feature:89:in `And I follow "Review"'

(link to the test)

Note that the test above it passes. They're identical except that one uses an ERB template, and one uses an Arbre template. This is only an issue on Rails 5.

[seanlinsley]

It would be best to try and identify the exact commit to Rails that introduced this bug.

[seanlinsley]

Most recent passing build: https://travis-ci.org/activeadmin/activeadmin/builds/110080134
Oldest failing build: https://travis-ci.org/activeadmin/activeadmin/builds/116005245

[seanlinsley]

Looks like 5.0.0.beta2 passed but 5.0.0.beta3 failed.

[seanlinsley]

rails/rails@v5.0.0.beta2...v5.0.0.beta3