Support scopes of STI classes as ability conditions

[honigc]

This fixes a bug introduced in #649 that broke using scopes of STI models as conditions. Without the change the new test produces this error:

ArgumentError:
Unknown key: "type". Valid keys are: :includes, :eager_load, :preload, :select, :group, :order, :joins, :left_outer_joins, :references, :extending, :unscope, :limit, :offset, :lock, :readonly, :reordering, :reverse_order, :distinct, :create_with, :skip_query_cache, :where, :having, :from
/usr/packages/ruby-2.7.2/gems/cancancan-3.2.1/lib/cancan/model_adapters/sti_normalizer.rb:34:in `build_rule_for_subclass'
/usr/packages/ruby-2.7.2/gems/cancancan-3.2.1/lib/cancan/model_adapters/sti_normalizer.rb:27:in `update_rule'
/usr/packages/ruby-2.7.2/gems/cancancan-3.2.1/lib/cancan/model_adapters/sti_normalizer.rb:13:in `block (2 levels) in normalize'
/usr/packages/ruby-2.7.2/gems/cancancan-3.2.1/lib/cancan/model_adapters/sti_normalizer.rb:12:in `select'
/usr/packages/ruby-2.7.2/gems/cancancan-3.2.1/lib/cancan/model_adapters/sti_normalizer.rb:12:in `block in normalize'
/usr/packages/ruby-2.7.2/gems/cancancan-3.2.1/lib/cancan/model_adapters/sti_normalizer.rb:11:in `delete_if'
/usr/packages/ruby-2.7.2/gems/cancancan-3.2.1/lib/cancan/model_adapters/sti_normalizer.rb:11:in `normalize'
/usr/packages/ruby-2.7.2/gems/cancancan-3.2.1/lib/cancan/model_adapters/active_record_adapter.rb:17:in `initialize'
/usr/packages/ruby-2.7.2/gems/cancancan-3.2.1/lib/cancan/ability.rb:172:in `new'
/usr/packages/ruby-2.7.2/gems/cancancan-3.2.1/lib/cancan/ability.rb:172:in `model_adapter'
/usr/packages/ruby-2.7.2/gems/cancancan-3.2.1/lib/cancan/model_additions.rb:24:in `accessible_by'

This happens because the STI normalizer calls #merge on the scope, which assumes the argument will be a relation or a hash of relation options. Using #where_values_hash in this case is the same thing already done in CanCan::Rule#inspect. This PR does not address the case of string conditions, which probably have a similar issue right now.

[JacobEvelyn]

Hi @coorasse—is there any interest in merging this PR? It would address a big pain point for us.

[ghost]

Suggested change

	sti_conditions = { subject.inheritance_column => subject.name }
	sti_conditions = { subject.inheritance_column => subject.sti_name }

[coorasse]

@honigc thank you very much, can you please look at the suggestions from @Liberatys and also rebase? Thanks!

[ghost]

LGTM 👍🏻 Small edit: { We recently changed subject.name to subject.sti_name }. Thank you for the change.

[honigc]

@coorasse @Liberatys Made the requested change and rebased. Thank you!

[ghost]

@coorasse LGTM

[coorasse]

Thanks!