Allow blank values to be stored in reactive cache

Reactive caching concern was using .present? to determine if it got
a valid value from the cache. This returns false for values such as
false, [], {}. Change this check to !.nil? instead.

app/models/concerns/reactive_caching.rb

@@ -76,7 +76,7 @@ module ReactiveCaching
 
       begin
         data = Rails.cache.read(full_reactive_cache_key(*args))
-        yield data if data.present?
+        yield data unless data.nil?
       rescue InvalidateReactiveCache
         refresh_reactive_cache!(*args)
         nil

changelogs/unreleased/56851-blank-values-in-reactive-cache.yml

@@ -0,0 +1,5 @@
+---
+title: Allow empty values such as [] to be stored in reactive cache
+merge_request: 25283
+author:
+type: fixed

spec/models/concerns/reactive_caching_spec.rb

@@ -25,7 +25,7 @@ describe ReactiveCaching, :use_clean_rails_memory_store_caching do
 
     def result
       with_reactive_cache do |data|
-        data / 2
+        data
       end
     end
   end
@@ -64,7 +64,7 @@ describe ReactiveCaching, :use_clean_rails_memory_store_caching do
         stub_reactive_cache(instance, 4)
       end
 
-      it { is_expected.to eq(2) }
+      it { is_expected.to eq(4) }
 
       it 'does not enqueue a background worker' do
         expect(ReactiveCachingWorker).not_to receive(:perform_async)
@@ -94,6 +94,14 @@ describe ReactiveCaching, :use_clean_rails_memory_store_caching do
         end
       end
     end
+
+    context 'when cache contains non-nil but blank value' do
+      before do
+        stub_reactive_cache(instance, false)
+      end
+
+      it { is_expected.to eq(false) }
+    end
   end
 
   describe '#clear_reactive_cache!' do

spec/support/helpers/reactive_caching_helpers.rb

@@ -10,7 +10,7 @@ module ReactiveCachingHelpers
   def stub_reactive_cache(subject = nil, data = nil, *qualifiers)
     allow(ReactiveCachingWorker).to receive(:perform_async)
     allow(ReactiveCachingWorker).to receive(:perform_in)
-    write_reactive_cache(subject, data, *qualifiers) if data
+    write_reactive_cache(subject, data, *qualifiers) unless data.nil?
   end
 
   def synchronous_reactive_cache(subject)