Rails 5: belongs_to_required_by_default prevents versioning of destroy events

[owenr]

When using the ActiveRecord configuration belongs_to_required_by_default (set to true for new Rails 5 projects), PaperTrail::Version tries to validate presence of the versioned item. Since versioning is done after destroy (by default), no matching item exists and the version creation silently fails.

See https://gist.github.com/owenr/60b34a2cdc13edf89412 for a test using the bug report template.

Proposed fix: explicitly make the item relationship optional.

[jaredbeck]

paper_trail_on_destroy already supports a before_destroy instead of the default after_destroy. Can we just change the default?

- def paper_trail_on_destroy(recording_order = 'after')
+ def paper_trail_on_destroy(recording_order = 'before')

If there are no drawbacks to changing the default, I'd prefer to keep the belongs_to :item relationship required.

[owenr]

The only drawback is that a reified model cannot be interrogated to see if it was destroyed. The version event still records the action. Since callback order is undefined in the current release, switching to :before seems to be a sensible approach.

[jaredbeck]

.. switching to :before seems to be a sensible approach.

Great! Our test suite now supports ActiveRecord 5 (support added by #684) but is not passing on AR 5 yet. Once our test suite is passing on AR 5, we can write a failing test for this issue.