Redis cache store: fail gracefully when max clients reached

activesupport/lib/active_support/cache/redis_cache_store.rb

@@ -471,7 +471,7 @@ def serialize_entries(entries, raw: false)
 
         def failsafe(method, returning: nil)
           yield
-        rescue ::Redis::BaseConnectionError => e
+        rescue ::Redis::BaseError => e
           handle_exception exception: e, method: method, returning: returning
           returning
         end

activesupport/test/cache/stores/redis_cache_store_test.rb

@@ -234,7 +234,13 @@ def ensure_connected
     end
   end
 
-  class FailureSafetyTest < StoreTest
+  class MaxClientsReachedRedisClient < Redis::Client
+    def ensure_connected
+      raise Redis::CommandError
+    end
+  end
+
+  class FailureSafetyFromUnavailableClientTest < StoreTest
     include FailureSafetyBehavior
 
     private
@@ -250,6 +256,21 @@ def emulating_unavailability
       end
   end
 
+  class FailureSafetyFromMaxClientsReachedErrorTest < StoreTest
+    include FailureSafetyBehavior
+
+    private
+      def emulating_unavailability
+        old_client = Redis.send(:remove_const, :Client)
+        Redis.const_set(:Client, MaxClientsReachedRedisClient)
+
+        yield ActiveSupport::Cache::RedisCacheStore.new
+      ensure
+        Redis.send(:remove_const, :Client)
+        Redis.const_set(:Client, old_client)
+      end
+  end
+
   class DeleteMatchedTest < StoreTest
     test "deletes keys matching glob" do
       @cache.write("foo", "bar")