Fix incorrect issueable counts

This change fixes incorrect issuable counts when the optimized label
filter feature flag is on.

app/models/concerns/optimized_issuable_label_filter.rb

@@ -28,7 +28,6 @@ module OptimizedIssuableLabelFilter
 
   # Taken from IssuableFinder
   def count_by_state
-    return super if root_namespace.nil?
     return super if Feature.disabled?(:optimized_issuable_label_filter, default_enabled: :yaml)
 
     count_params = params.merge(state: nil, sort: nil, force_cte: true)
@@ -40,7 +39,11 @@ module OptimizedIssuableLabelFilter
       .group(:state_id)
       .count
 
-    counts = state_counts.transform_keys { |key| count_key(key) }
+    counts = Hash.new(0)
+
+    state_counts.each do |key, value|
+      counts[count_key(key)] += value
+    end
 
     counts[:all] = counts.values.sum
     counts.with_indifferent_access

changelogs/unreleased/fix-incorrect-issuable-counts.yml

+---
+title: Fix incorrect issue and merge requests counts with filters
+merge_request: 61230
+author:
+type: fixed

spec/finders/merge_requests_finder_spec.rb

@@ -866,5 +866,36 @@ RSpec.describe MergeRequestsFinder do
         end
       end
     end
+
+    describe '#count_by_state' do
+      let_it_be(:user) { create(:user) }
+      let_it_be(:project) { create(:project, :repository) }
+      let_it_be(:labels) { create_list(:label, 2, project: project) }
+      let_it_be(:merge_requests) { create_list(:merge_request, 4, :unique_branches, author: user, target_project: project, source_project: project, labels: labels) }
+
+      before do
+        project.add_developer(user)
+      end
+
+      context 'when filtering by multiple labels' do
+        it 'returns the correnct counts' do
+          counts = described_class.new(user, { label_name: labels.map(&:name) }).count_by_state
+
+          expect(counts[:all]).to eq(merge_requests.size)
+        end
+      end
+
+      context 'when filtering by approved_by_usernames' do
+        before do
+          merge_requests.each { |mr| mr.approved_by_users << user }
+        end
+
+        it 'returns the correnct counts' do
+          counts = described_class.new(user, { approved_by_usernames: [user.username] }).count_by_state
+
+          expect(counts[:all]).to eq(merge_requests.size)
+        end
+      end
+    end
   end
 end