a couple of tests proving that LaterInvocator.ensureFlushRequested is really needed

platform/platform-tests/testSrc/com/intellij/openapi/application/impl/LaterInvocatorTest.java

@@ -15,10 +15,12 @@
  */
 package com.intellij.openapi.application.impl;
 
+import com.intellij.openapi.application.Application;
 import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.application.ModalityState;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.util.Conditions;
+import com.intellij.openapi.util.EmptyRunnable;
 import com.intellij.testFramework.LoggedErrorProcessor;
 import com.intellij.testFramework.PlatformTestCase;
 import com.intellij.testFramework.SkipInHeadlessEnvironment;
@@ -34,6 +36,7 @@ import java.util.ArrayList;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 @SuppressWarnings({"SSBasedInspection", "SynchronizeOnThis"})
 @SkipInHeadlessEnvironment
@@ -577,4 +580,33 @@ public class LaterInvocatorTest extends PlatformTestCase {
       assertTrue(e.getMessage(), e.getMessage().contains("Access is allowed from event dispatch thread only"));
     }
   }
+
+  public void testDispatchInvocationEventsWorksForJustSubmitted() {
+    Application app = ApplicationManager.getApplication();
+    app.invokeAndWait(() -> {
+      app.invokeLater(() -> {
+        myOrder.add("1");
+        assertOrderedEquals(myOrder, "1");
+        UIUtil.dispatchAllInvocationEvents();
+        assertOrderedEquals(myOrder, "1", "2");
+      });
+      app.invokeLater(new MyRunnable("2"));
+      UIUtil.dispatchAllInvocationEvents();
+    });
+    assertOrderedEquals(myOrder, "1", "2");
+  }
+
+  public void testDispatchInvocationEventsVsInvokeLaterFromBgThreadRace() {
+    Application app = ApplicationManager.getApplication();
+    app.invokeAndWait(() -> {
+      for (int i = 0; i < 1000; i++) {
+        AtomicBoolean executed = new AtomicBoolean();
+        app.executeOnPooledThread(() -> app.invokeLater(EmptyRunnable.INSTANCE));
+        app.invokeLater(() -> executed.set(true));
+        UIUtil.dispatchAllInvocationEvents();
+        assertTrue(executed.get());
+      }
+    });
+
+  }
 }