test(stealth): await complete main-thread admin callbacks

src/test/java/games/dmg/spigotstealth/StealthAdminCommandTest.java

@@ -80,7 +80,10 @@ class StealthAdminCommandTest {
             fixture.command.onCommand(
                     sender, command, "stealthadmin", new String[] {"sleepcount", "include"});
 
-            verify(sender, org.mockito.Mockito.timeout(1000)).sendMessage(contains("now included"));
+            verify(sender, never()).sendMessage(contains("now included"));
+            assertEquals(List.of(), fixture.audit);
+            fixture.runMainThreadCallback();
+            verify(sender).sendMessage(contains("now included"));
             assertEquals(SleepCountPolicy.INCLUDE, fixture.manager.snapshot().sleepCountPolicy());
             verify(fixture.presentation).refreshSleepCountPolicy();
             org.junit.jupiter.api.Assertions.assertTrue(fixture.audit.stream()
@@ -125,7 +128,10 @@ class StealthAdminCommandTest {
         try (Fixture fixture = fixture(playerId)) {
             CommandSender sender = sender(true);
             fixture.command.onCommand(sender, mock(Command.class), "stealthadmin", new String[] {"grant", playerId.toString()});
-            verify(sender, org.mockito.Mockito.timeout(1000)).sendMessage(contains("granted"));
+            verify(sender, never()).sendMessage(contains("granted"));
+            assertEquals(List.of(), fixture.audit);
+            fixture.runMainThreadCallback();
+            verify(sender).sendMessage(contains("granted"));
             org.junit.jupiter.api.Assertions.assertTrue(fixture.manager.snapshot().player(playerId).unlocked());
             org.junit.jupiter.api.Assertions.assertTrue(fixture.audit.stream().anyMatch(message -> message.contains("grant") && message.contains(playerId.toString())));
         }
@@ -167,16 +173,30 @@ class StealthAdminCommandTest {
                 manager, progression, presentation, ignored -> { }, List::of);
         KnownPlayerResolver resolver = new KnownPlayerResolver(manager::snapshot, List::of);
         ArrayList<String> audit = new ArrayList<>();
+        var mainThread = new java.util.concurrent.LinkedBlockingQueue<Runnable>();
         StealthAdminCommand command = new StealthAdminCommand(
-                administration, resolver, Runnable::run, audit::add, Duration.ofHours(8));
+                administration, resolver, mainThread::add, audit::add, Duration.ofHours(8));
-        return new Fixture(manager, command, presentation, audit);
+        return new Fixture(manager, command, presentation, audit, mainThread);
     }
 
     private record Fixture(
             StealthStateManager manager,
             StealthAdminCommand command,
             IdentityPresentation presentation,
-            ArrayList<String> audit) implements AutoCloseable {
+            ArrayList<String> audit,
+            java.util.concurrent.BlockingQueue<Runnable> mainThread) implements AutoCloseable {
+        void runMainThreadCallback() {
+            // A reply is emitted before the audit append. Await and run the whole scheduled callback,
+            // not just the reply invocation, and never read the ArrayList concurrently with the I/O thread.
+            try {
+                Runnable callback = mainThread.poll(5, java.util.concurrent.TimeUnit.SECONDS);
+                org.junit.jupiter.api.Assertions.assertNotNull(callback, "Expected a scheduled main-thread completion");
+                callback.run();
+            } catch (InterruptedException exception) {
+                Thread.currentThread().interrupt();
+                throw new AssertionError("Interrupted waiting for command completion", exception);
+            }
+        }
         @Override public void close() { manager.close(); }
     }
 }