Add the ability to simulate a slow connection

Can set QA_SIMULATE_SLOW_CONNECTION to simulate a slow connection
QA_SLOW_CONNECTION_LATENCY_MS sets additional latency in ms
QA_SLOW_CONNECTION_THROUGHPUT_KBPS sets the maximum throughput in kbps

qa/qa/runtime/browser.rb

@@ -156,6 +156,8 @@ module QA
         def perform(&block)
           visit(url)
 
+          simulate_slow_connection if Runtime::Env.simulate_slow_connection?
+
           page_class.validate_elements_present!
 
           if QA::Runtime::Env.qa_cookies
@@ -178,6 +180,28 @@ module QA
         def clear!
           visit(url)
           reset_session!
+          @network_conditions_configured = false
+        end
+
+        private
+
+        def simulate_slow_connection
+          return if @network_conditions_configured
+
+          QA::Runtime::Logger.info(
+            <<~MSG.tr("\n", " ")
+              Simulating a slow connection with additional latency
+              of #{Runtime::Env.slow_connection_latency} ms and a maximum
+              throughput of #{Runtime::Env.slow_connection_throughput} kbps
+            MSG
+          )
+
+          Capybara.current_session.driver.browser.network_conditions = {
+            latency: Runtime::Env.slow_connection_latency,
+            throughput: Runtime::Env.slow_connection_throughput * 1000
+          }
+
+          @network_conditions_configured = true
         end
       end
     end

qa/qa/runtime/env.rb

@@ -261,6 +261,22 @@ module QA
         ENV['QA_RUNTIME_SCENARIO_ATTRIBUTES']
       end
 
+      def disable_rspec_retry?
+        enabled?(ENV['QA_DISABLE_RSPEC_RETRY'], default: false)
+      end
+
+      def simulate_slow_connection?
+        enabled?(ENV['QA_SIMULATE_SLOW_CONNECTION'], default: false)
+      end
+
+      def slow_connection_latency
+        ENV.fetch('QA_SLOW_CONNECTION_LATENCY_MS', 2000).to_i
+      end
+
+      def slow_connection_throughput
+        ENV.fetch('QA_SLOW_CONNECTION_THROUGHPUT_KBPS', 32).to_i
+      end
+
       def gitlab_qa_loop_runner_minutes
         ENV.fetch('GITLAB_QA_LOOP_RUNNER_MINUTES', 1).to_i
       end

qa/spec/spec_helper.rb

@@ -62,7 +62,7 @@ RSpec.configure do |config|
   # show exception that triggers a retry if verbose_retry is set to true
   config.display_try_failure_messages = true
 
-  if ENV['CI']
+  if ENV['CI'] && !QA::Runtime::Env.disable_rspec_retry?
     config.around do |example|
       retry_times = example.metadata.key?(:quarantine) ? 1 : 2
       example.run_with_retry retry: retry_times