Replace deprecated Sidekiq testing API with new Sidekiq 8.1+ API

`require "sidekiq/testing"` is deprecated and will be removed in
Sidekiq 9.0. The new API makes test mode activation explicit:

- `require 'sidekiq/testing'` → `Sidekiq.testing!(:fake)`
- `Sidekiq::Testing.inline! { }` → `Sidekiq.testing!(:inline) { }`

Author: mattmenefee

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## master (unreleased)
+
+### Changes
+
+* Replace deprecated `Sidekiq::Testing` API with new `Sidekiq 8.1+` testing API. ([@mattmenefee][])
+
 ## 8.0.1 (2026-03-12)
 
 ### New Features
@@ -873,6 +879,7 @@
 [@MarkMurphy]: https://github.com/MarkMurphy
 [@marshall]: https://github.com/marshall
 [@matchbookmac]: https://github.com/matchbookmac
+[@mattmenefee]: https://github.com/mattmenefee
 [@matthee]: https://github.com/matthee
 [@mattzollinhofer]: https://github.com/mattzollinhofer
 [@menglewis]: https://github.com/menglewis

spec/chewy/strategy/delayed_sidekiq/scheduler_spec.rb

@@ -1,7 +1,7 @@
 require 'spec_helper'
 
 if defined?(Sidekiq)
-  require 'sidekiq/testing'
+  Sidekiq.testing!(:fake)
 
   describe Chewy::Strategy::DelayedSidekiq::Scheduler do
     before do

spec/chewy/strategy/delayed_sidekiq/worker_spec.rb

@@ -1,7 +1,7 @@
 require 'spec_helper'
 
 if defined?(Sidekiq)
-  require 'sidekiq/testing'
+  Sidekiq.testing!(:fake)
   require 'redis'
 
   describe Chewy::Strategy::DelayedSidekiq::Worker do

spec/chewy/strategy/delayed_sidekiq_spec.rb

@@ -1,7 +1,7 @@
 require 'spec_helper'
 
 if defined?(Sidekiq)
-  require 'sidekiq/testing'
+  Sidekiq.testing!(:fake)
   require 'redis'
 
   describe Chewy::Strategy::DelayedSidekiq do
@@ -73,7 +73,7 @@
 
           expect($stdout).not_to receive(:puts)
 
-          Sidekiq::Testing.inline! do
+          Sidekiq.testing!(:inline) do
             expect { [city, other_city].map(&:save!) }
               .to update_index(CitiesIndex, strategy: :delayed_sidekiq)
               .and_reindex(city, other_city).only
@@ -114,7 +114,7 @@ def expected_at_time
 
           expect($stdout).to receive(:puts).with('hello') # check that reindex_wrapper works
 
-          Sidekiq::Testing.inline! do
+          Sidekiq.testing!(:inline) do
             expect { [city, other_city].map(&:save!) }
               .to update_index(CitiesIndex, strategy: :delayed_sidekiq)
               .and_reindex(city, other_city).only

spec/chewy/strategy/lazy_sidekiq_spec.rb

@@ -1,7 +1,7 @@
 require 'spec_helper'
 
 if defined?(Sidekiq)
-  require 'sidekiq/testing'
+  Sidekiq.testing!(:fake)
 
   describe Chewy::Strategy::LazySidekiq do
     around do |example|
@@ -39,7 +39,7 @@
                 ))
           .and_call_original
           .once
-        Sidekiq::Testing.inline! do
+        Sidekiq.testing!(:inline) do
           expect { [city, other_city].map(&:save!) }
             .to update_index(CitiesIndex, strategy: :lazy_sidekiq)
             .and_reindex(city, other_city).only
@@ -60,7 +60,7 @@
                 ))
           .and_call_original
           .once
-        Sidekiq::Testing.inline! do
+        Sidekiq.testing!(:inline) do
           expect { [city, other_city].map(&:destroy) }.to update_index(CitiesIndex, strategy: :sidekiq)
         end
       end
@@ -71,7 +71,7 @@
         expect(other_city).to receive(:run_chewy_callbacks).and_call_original
 
         expect do
-          Sidekiq::Testing.inline! do
+          Sidekiq.testing!(:inline) do
             Chewy::Strategy::LazySidekiq::IndicesUpdateWorker.new.perform({'City' => [city.id, other_city.id]})
           end
         end.to update_index(CitiesIndex).and_reindex(city, other_city).only
@@ -88,7 +88,7 @@
           expect(other_city).to receive(:run_chewy_callbacks).and_call_original
 
           expect do
-            Sidekiq::Testing.inline! do
+            Sidekiq.testing!(:inline) do
               Chewy::Strategy::LazySidekiq::IndicesUpdateWorker.new.perform({'City' => [city.id, other_city.id]})
             end
           end.to update_index(CitiesIndex).and_reindex(city, other_city).only.no_refresh
@@ -97,7 +97,7 @@
     end
 
     context 'integration' do
-      around { |example| Sidekiq::Testing.inline! { example.run } }
+      around { |example| Sidekiq.testing!(:inline) { example.run } }
 
       let(:update_condition) { true }
 

spec/chewy/strategy/sidekiq_spec.rb

@@ -1,7 +1,7 @@
 require 'spec_helper'
 
 if defined?(Sidekiq)
-  require 'sidekiq/testing'
+  Sidekiq.testing!(:fake)
 
   describe Chewy::Strategy::Sidekiq do
     around do |example|
@@ -31,7 +31,7 @@
 
     specify do
       expect(Sidekiq::Client).to receive(:push).with(hash_including('queue' => 'low')).and_call_original
-      Sidekiq::Testing.inline! do
+      Sidekiq.testing!(:inline) do
         expect { [city, other_city].map(&:save!) }
           .to update_index(CitiesIndex, strategy: :sidekiq)
           .and_reindex(city, other_city).only