fix(STI): compress rules per subjects

CHANGELOG.md

@@ -1,9 +1,18 @@
+## 3.6.2
+
+* [#855](https://github.com/CanCanCommunity/cancancan/pull/855): Fix issue with compressing STI rules. ([@sjoulbak][])
+
+## 3.6.1
+
+* [#847](https://github.com/CanCanCommunity/cancancan/pull/847): Fix: rule_spec should honor DB setting ([@tardate][])
+
 ## 3.6.0
 
 * [#849](https://github.com/CanCanCommunity/cancancan/pull/849): Update tests matrix. ([@coorasse][])
 * [#843](https://github.com/CanCanCommunity/cancancan/pull/843): Compress duplicate rules. ([@MrChoclate][])
 * [#841](https://github.com/CanCanCommunity/cancancan/pull/841): New https://cancancan.dev website. ([@pandermatt][])
-* [#839](https://github.com/CanCanCommunity/cancancan/pull/839): switch from database column detection to Rails attributes detection. ([@kalsan][])
+* [#839](https://github.com/CanCanCommunity/cancancan/pull/839): Switch from database column detection to Rails attributes detection. ([@kalsan][])
+
 ## 3.5.0
 
 * [#653](https://github.com/CanCanCommunity/cancancan/pull/653): Add support for using an nil relation as a condition. ([@ghiculescu][])
@@ -716,3 +725,5 @@ Please read the [guide on migrating from CanCanCan 2.x to 3.0](https://github.co
 [@MrChoclate]: https://github.com/MrChoclate
 [@pandermatt]: https://github.com/pandermatt
 [@kalsan]: https://github.com/kalsan
+[@tardate]: https://github.com/tardate
+[@sjoulbak]: https://github.com/sjoulbak

lib/cancan/rules_compressor.rb

@@ -31,9 +31,9 @@ def compress(array)
     def simplify(rules)
       seen = Set.new
       rules.reverse_each.filter_map do |rule|
-        next if seen.include?(rule.conditions)
+        next if seen.include?(rule.subjects => rule.conditions)
 
-        seen.add(rule.conditions)
+        seen.add(rule.subjects => rule.conditions)
         rule
       end.reverse
     end

lib/cancan/version.rb

@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module CanCan
-  VERSION = '3.5.0'.freeze
+  VERSION = '3.6.2'.freeze
 end

spec/cancan/rule_compressor_spec.rb

@@ -137,6 +137,32 @@ def cannot(action, subject, args = nil)
     end
   end
 
+  context 'when STI is in use' do
+    before do
+      class Pet
+      end
+
+      class Cat < Pet
+      end
+
+      class Dog < Pet
+      end
+    end
+
+    let(:rules) do
+      [
+        can(:read, Pet, capacity: 5),
+        can(:read, Cat, capacity: 5),
+        can(:read, Dog, capacity: 6),
+        can(:read, Pet, capacity: 5)
+      ]
+    end
+
+    it 'minimizes the rules, by removing useless previous rules' do
+      expect(described_class.new(rules).rules_collapsed).to eq [rules[1], rules[2], rules[3]]
+    end
+  end
+
   # TODO: not supported yet
   xcontext 'merges rules' do
     let(:rules) do