#16612 fix flaky test: wait until the downloads folder gets deleted

After stopping a Grid node, the folder is deleted asynchronously (by cache removal listener). So we need to wait for it in test.

Author: asolntsev

java/test/org/openqa/selenium/grid/node/NodeTest.java

@@ -149,7 +149,7 @@ public HttpResponse execute(HttpRequest req) throws UncheckedIOException {
             .add(caps, new TestSessionFactory((id, c) -> new Handler(c)))
             .maximumConcurrentSessions(2);
     if (isDownloadsTestCase) {
-      builder = builder.enableManagedDownloads(true).sessionTimeout(Duration.ofSeconds(1));
+      builder = builder.enableManagedDownloads(true).sessionTimeout(ofSeconds(1));
     }
     local = builder.build();
     local2 = builder.build();
@@ -568,7 +568,7 @@ void canUploadAFile() throws IOException {
     assertThat(new String(Files.readAllBytes(uploadDir.listFiles()[0].toPath()))).isEqualTo(hello);
 
     node.stop(session.getId());
-    assertThat(baseDir).doesNotExist();
+    waitUntilDirGetsDeleted(baseDir);
   }
 
   @Test
@@ -644,7 +644,7 @@ void canDownloadMultipleFile() throws IOException {
       TemporaryFilesystem downloadsTfs = local.getDownloadsFilesystem(session.getId());
       File someDir = getTemporaryFilesystemBaseDir(downloadsTfs);
       node.stop(session.getId());
-      assertThat(someDir).doesNotExist();
+      waitUntilDirGetsDeleted(someDir);
     }
   }
 
@@ -975,6 +975,10 @@ private List<String> listFileDownloads(SessionId sessionId) {
     return (List<String>) map.get("names");
   }
 
+  private void waitUntilDirGetsDeleted(File dir) {
+    new FluentWait<>(dir).withTimeout(ofSeconds(2)).until(file -> !file.exists());
+  }
+
   private static class MyClock extends Clock {
 
     private final AtomicReference<Instant> now;