Fix flaky Redis-Sessions spec

spec/lib/gitlab/redis/sessions_spec.rb

@@ -44,20 +44,23 @@ RSpec.describe Gitlab::Redis::Sessions do
   describe '#store' do
     subject { described_class.store(namespace: described_class::SESSION_NAMESPACE) }
 
-    context 'when redis.sessions configuration is provided' do
+    context 'when redis.sessions configuration is NOT provided' do
       it 'instantiates ::Redis instance' do
         expect(described_class).to receive(:config_fallback?).and_return(true)
         expect(subject).to be_instance_of(::Redis::Store)
       end
     end
 
-    context 'when redis.sessions configuration is not provided' do
+    context 'when redis.sessions configuration is provided' do
+      before do
+        allow(described_class).to receive(:config_fallback?).and_return(false)
+      end
+
       it 'instantiates an instance of MultiStore' do
-        expect(described_class).to receive(:config_fallback?).and_return(false)
         expect(subject).to be_instance_of(::Gitlab::Redis::MultiStore)
       end
-    end
 
       it_behaves_like 'multi store feature flags', :use_primary_and_secondary_stores_for_sessions, :use_primary_store_as_default_for_sessions
     end
+  end
 end

spec/support/redis/redis_new_instance_shared_examples.rb

@@ -8,10 +8,16 @@ RSpec.shared_examples "redis_new_instance_shared_examples" do |name, fallback_cl
   let(:fallback_config_file) { nil }
 
   before do
+    fallback_class.remove_instance_variable(:@_raw_config) rescue nil
+
     allow(fallback_class).to receive(:config_file_name).and_return(fallback_config_file)
   end
 
-  include_examples "redis_shared_examples"
+  after do
+    fallback_class.remove_instance_variable(:@_raw_config) rescue nil
+  end
+
+  it_behaves_like "redis_shared_examples"
 
   describe '.config_file_name' do
     subject { described_class.config_file_name }