misc: update ydoc scheduler tests

Author: 4e6

lib/java/ydoc-server/src/main/java/org/enso/ydoc/server/YdocScheduledExecutorService.java

@@ -469,8 +469,8 @@ public <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, Ti
    * <p>This method must be called from the owner thread (the thread that created this service).
    * Tasks are polled individually from the queues on each iteration so that tasks submitted during
    * execution (e.g., incoming WebSocket messages) become visible immediately. High-priority tasks
-   * are always checked first, ensuring latency-sensitive operations are not starved by large batches
-   * of bulk work.
+   * are always checked first, ensuring latency-sensitive operations are not starved by large
+   * batches of bulk work.
    *
    * <p>Poll order: high-priority queue → regular immediate queue → ready scheduled tasks.
    *

lib/java/ydoc-server/src/test/java/org/enso/ydoc/server/YdocScheduledExecutorServiceTest.java

@@ -357,6 +357,68 @@ public void testScheduledCallableCompareToIsStable() throws Exception {
     }
   }
 
+  @Test
+  public void testHighPriorityTasksExecuteFirst() {
+    YdocScheduledExecutorService service = new YdocScheduledExecutorService();
+    List<String> executionOrder = new ArrayList<>();
+
+    // Submit regular tasks first
+    service.submit(() -> executionOrder.add("regular1"));
+    service.submit(() -> executionOrder.add("regular2"));
+
+    // Submit high-priority tasks via execute() with HighPriorityRunnable
+    service.execute(
+        new YdocScheduledExecutorService.HighPriorityRunnable(() -> executionOrder.add("high1")));
+    service.execute(
+        new YdocScheduledExecutorService.HighPriorityRunnable(() -> executionOrder.add("high2")));
+
+    service.processPendingTasks();
+
+    // High-priority tasks should execute before regular tasks
+    assertEquals(List.of("high1", "high2", "regular1", "regular2"), executionOrder);
+  }
+
+  @Test
+  public void testHighPriorityViewRoutesToHighPriorityQueue() {
+    YdocScheduledExecutorService service = new YdocScheduledExecutorService();
+    var highPriorityView = service.createHighPriorityView();
+    List<String> executionOrder = new ArrayList<>();
+
+    // Submit regular tasks directly
+    service.submit(() -> executionOrder.add("regular1"));
+    service.submit(() -> executionOrder.add("regular2"));
+
+    // Submit via high-priority view
+    highPriorityView.execute(() -> executionOrder.add("high1"));
+    highPriorityView.execute(() -> executionOrder.add("high2"));
+
+    service.processPendingTasks();
+
+    // View tasks should execute before regular tasks
+    assertEquals(List.of("high1", "high2", "regular1", "regular2"), executionOrder);
+  }
+
+  @Test
+  public void testHighPriorityTasksInterleavedDuringProcessing() {
+    YdocScheduledExecutorService service = new YdocScheduledExecutorService();
+    var highPriorityView = service.createHighPriorityView();
+    List<String> executionOrder = new ArrayList<>();
+
+    // Submit regular tasks where the first one submits a high-priority task during execution
+    service.submit(
+        () -> {
+          executionOrder.add("regular1");
+          // Simulate a WebSocket message arriving while processing regular tasks
+          highPriorityView.execute(() -> executionOrder.add("high-interleaved"));
+        });
+    service.submit(() -> executionOrder.add("regular2"));
+
+    service.processPendingTasks();
+
+    // The high-priority task submitted during regular1 should execute before regular2
+    assertEquals(List.of("regular1", "high-interleaved", "regular2"), executionOrder);
+  }
+
   @Test
   public void testEventLoopPattern() throws InterruptedException {
     YdocScheduledExecutorService service = new YdocScheduledExecutorService();