Betterment/UnscopedFind Improvement: Flag `unscoped`

[6f6d6172]

UnscopedFind has made the assumption that if you're doing a find off of an object (e.g. current_user), your query will be scoped to whatever belongs to that object. However, it turns out there's an unscoped method which when called at any point will remove any scopes, effectively letting you find any object regardless of who owns it.

For example, current_user.cats.find(params[:id]) will not raise an offense because the find call on cats is scoped to the current user. This same logic is erroneously extended to current_user.cats.unscoped.find(params[:id]), which does the same query but without the where clause that scopes it to the current user.

This cop should be modified to flag any uses of unscoped.

I was able to put together this diff that is the bare minimum needed to start detecting unscoped calls, but I haven't taken the time to sit down and list out test cases or write any specs.

diff --git a/lib/rubocop/cop/betterment/unscoped_find.rb b/lib/rubocop/cop/betterment/unscoped_find.rb
index fe3aa8e..bc6a71d 100644
--- a/lib/rubocop/cop/betterment/unscoped_find.rb
+++ b/lib/rubocop/cop/betterment/unscoped_find.rb
@@ -31,6 +31,10 @@ module RuboCop
           (send (const ... _) {#{FINDS.map(&:inspect).join(' ')}} ...)
         PATTERN
 
+        def_node_matcher :unscoped?, <<-PATTERN
+          (send (send ... :unscoped) {#{FINDS.map(&:inspect).join(' ')}} ...)
+        PATTERN
+
         def_node_search :find_graphql_namespace_nodes, <<~PATTERN, name: GRAPHQL_PATTERN
           (const _ %name)
         PATTERN
@@ -49,6 +53,7 @@ module RuboCop
           _, _, *arg_nodes = *node # rubocop:disable InternalAffairs/NodeDestructuring
           return unless
             (
+              unscoped?(node) ||
               find?(node) ||
               custom_scope_find?(node) ||
               static_method_name(node.method_name)

tl;dr todo

• flag all unscoped
• list out test cases
• write tests