Stub SHUTDOWN_GRACE_TIME const in thread pool test

lib/puma/thread_pool.rb

@@ -285,7 +285,7 @@ def auto_reap!(timeout=5)
     # Next, wait an extra +grace+ seconds then force-kill remaining threads.
     # Finally, wait +kill_grace+ seconds for remaining threads to exit.
     #
-    def shutdown(timeout=-1, grace: SHUTDOWN_GRACE_TIME, kill_grace: 1)
+    def shutdown(timeout=-1)
       threads = @mutex.synchronize do
         @shutdown = true
         @not_empty.broadcast
@@ -309,18 +309,18 @@ def shutdown(timeout=-1, grace: SHUTDOWN_GRACE_TIME, kill_grace: 1)
           end
         end
 
-        # Wait for threads to finish after +timeout+ seconds.
+        # Wait +timeout+ seconds for threads to finish.
         join.call(timeout)
 
-        # If threads are still running, raise ForceShutdown.
+        # If threads are still running, raise ForceShutdown and wait to finish.
         threads.each do |t|
           t.raise ForceShutdown
         end
-        join.call(grace)
+        join.call(SHUTDOWN_GRACE_TIME)
 
-        # If threads are _still_ running, forcefully kill them.
+        # If threads are _still_ running, forcefully kill them and wait to finish.
         threads.each(&:kill)
-        join.call(kill_grace)
+        join.call(1)
       end
 
       @spawned = 0

test/helper.rb

@@ -143,3 +143,16 @@ def full_name
     end
   end
 end
+
+module StubConst
+  # Stub constant for the duration of a block
+  def stub_const(name, val, &block)
+    orig = const_defined?(name) && remove_const(name)
+    const_set(name, val)
+    yield
+  ensure
+    remove_const(name)
+    const_set(name, orig) if orig
+  end
+end
+Module.include StubConst

test/test_thread_pool.rb

@@ -290,7 +290,9 @@ def test_shutdown_with_grace
 
     @work_mutex.synchronize do
       @work_done.wait(@work_mutex, 5)
-      pool.shutdown(timeout, grace: grace)
+      Puma::ThreadPool.stub_const(:SHUTDOWN_GRACE_TIME, grace) do
+        pool.shutdown(timeout)
+      end
       finish = true
       assert_equal 0, pool.spawned
       assert_equal 2, rescued.length