Add `clear_association_scope_cache` method

In the tests if I were to call `post.categorizations.to_a` and then later call
`post.categorizations.to_a` expecting to have different results the 2 queries
would be the same because of the caching involved in
`@association_scope_cache`. The chain gets cached and the queries will
be the same even if they are not supposed to be (i.e. testing an order
dependent scoping issue).

I found this issue because I was working on a bug with cached scoped
in hm:t and hm:t polymorphic relationships but `capture_sql` was
outputting the wrong SQL to write a good test.

1 files changed, 15 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb
index e4704b5b3e..4265afc0a5 100644
--- a/activerecord/lib/active_record/reflection.rb
+++ b/activerecord/lib/active_record/reflection.rb
@@ -370,6 +370,12 @@ module ActiveRecord
         [self]
       end
 
+      # This is for clearing cache on the reflection. Useful for tests that need to compare
+      # SQL queries on associations.
+      def clear_association_scope_cache # :nodoc:
+        @association_scope_cache.clear
+      end
+
       def nested?
         false
       end
@@ -706,6 +712,15 @@ module ActiveRecord
         end
       end
 
+      # This is for clearing cache on the reflection. Useful for tests that need to compare
+      # SQL queries on associations.
+      def clear_association_scope_cache # :nodoc:
+        @chain = nil
+        delegate_reflection.clear_association_scope_cache
+        source_reflection.clear_association_scope_cache
+        through_reflection.clear_association_scope_cache
+      end
+
       # Consider the following example:
       #
       #   class Person