test: retry count assertion on session invalidation (#135)

Session context tests check the counter value hold by a session bean right
after invalidating the Vaadin session. Since the counter is incremented
in the PreDestroy hook, it may happen that when the test checks for the
counter value, the callback has not yet been invoked.
This change retries the counter check for at most on second, to preven
ttest flakyness.

Fixes #126

integration-tests/common-test-code/src/test/java/com/vaadin/flow/quarkus/it/AbstractCdiIT.java

@@ -41,6 +41,17 @@ protected String getText(String id) {
         return findElement(By.id(id)).getText();
     }
 
+    protected void waitForCount(int expectedCount, String counter) {
+        waitUntil(driver -> {
+            try {
+                assertCountEquals(expectedCount, counter);
+                return true;
+            } catch (Exception ex) {
+                return false;
+            }
+        }, 1);
+    }
+
     protected void assertCountEquals(int expectedCount, String counter)
             throws IOException {
         Assert.assertEquals(expectedCount, getCount(counter));

integration-tests/common-test-code/src/test/java/com/vaadin/flow/quarkus/it/SessionContextCloseIT.java

@@ -48,6 +48,6 @@ public void vaadinSessionCloseDestroysSessionContext() throws Exception {
 
     private void assertDestroyCountEquals(int expectedCount)
             throws IOException {
-        assertCountEquals(expectedCount, DESTROY_COUNT);
+        waitForCount(expectedCount, DESTROY_COUNT);
     }
 }

integration-tests/common-test-code/src/test/java/com/vaadin/flow/quarkus/it/SessionContextIT.java

@@ -83,7 +83,7 @@ private void assertLabelEquals(String expected) {
 
     private void assertDestroyCountEquals(int expectedCount)
             throws IOException {
-        assertCountEquals(expectedCount, DESTROY_COUNT);
+        waitForCount(expectedCount, DESTROY_COUNT);
     }
 
     private static Logger getLogger() {