diff --git a/jetty-websocket/websocket-jetty-tests/src/test/java/org/eclipse/jetty/websocket/tests/JettyWebSocketFilterTest.java b/jetty-websocket/websocket-jetty-tests/src/test/java/org/eclipse/jetty/websocket/tests/JettyWebSocketFilterTest.java
index e1786c196b8c..c0be53db2630 100644
--- a/jetty-websocket/websocket-jetty-tests/src/test/java/org/eclipse/jetty/websocket/tests/JettyWebSocketFilterTest.java
+++ b/jetty-websocket/websocket-jetty-tests/src/test/java/org/eclipse/jetty/websocket/tests/JettyWebSocketFilterTest.java
@@ -21,19 +21,24 @@
 import java.net.URI;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.TimeUnit;
+import javax.servlet.http.HttpServlet;
 
 import org.eclipse.jetty.server.Server;
 import org.eclipse.jetty.server.ServerConnector;
+import org.eclipse.jetty.servlet.FilterHolder;
 import org.eclipse.jetty.servlet.ServletContextHandler;
+import org.eclipse.jetty.servlet.ServletHolder;
+import org.eclipse.jetty.util.component.AbstractLifeCycle;
 import org.eclipse.jetty.websocket.api.Session;
 import org.eclipse.jetty.websocket.client.WebSocketClient;
 import org.eclipse.jetty.websocket.server.JettyWebSocketServerContainer;
 import org.eclipse.jetty.websocket.server.config.JettyWebSocketServletContainerInitializer;
+import org.eclipse.jetty.websocket.util.server.WebSocketUpgradeFilter;
 import org.junit.jupiter.api.AfterEach;
-import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.instanceOf;
 import static org.hamcrest.Matchers.is;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
@@ -45,8 +50,17 @@ public class JettyWebSocketFilterTest
     private WebSocketClient client;
     private ServletContextHandler contextHandler;
 
-    @BeforeEach
-    public void start() throws Exception
+    public void start(JettyWebSocketServletContainerInitializer.Configurator configurator) throws Exception
+    {
+        start(configurator, null);
+    }
+
+    public void start(ServletHolder servletHolder) throws Exception
+    {
+        start(null, servletHolder);
+    }
+
+    public void start(JettyWebSocketServletContainerInitializer.Configurator configurator, ServletHolder servletHolder) throws Exception
     {
         server = new Server();
         connector = new ServerConnector(server);
@@ -54,9 +68,11 @@ public void start() throws Exception
 
         contextHandler = new ServletContextHandler(ServletContextHandler.SESSIONS);
         contextHandler.setContextPath("/");
+        if (servletHolder != null)
+            contextHandler.addServlet(servletHolder, "/");
         server.setHandler(contextHandler);
 
-        JettyWebSocketServletContainerInitializer.configure(contextHandler, null);
+        JettyWebSocketServletContainerInitializer.configure(contextHandler, configurator);
         server.start();
 
         client = new WebSocketClient();
@@ -70,9 +86,37 @@ public void stop() throws Exception
         server.stop();
     }
 
+    @Test
+    public void testWebSocketUpgradeFilter() throws Exception
+    {
+        start((context, container) -> container.addMapping("/", EchoSocket.class));
+
+        // After mapping is added we have an UpgradeFilter.
+        assertThat(contextHandler.getServletHandler().getFilters().length, is(1));
+        FilterHolder filterHolder = contextHandler.getServletHandler().getFilter("WebSocketUpgradeFilter");
+        assertNotNull(filterHolder);
+        assertThat(filterHolder.getState(), is(AbstractLifeCycle.STARTED));
+        assertThat(filterHolder.getFilter(), instanceOf(WebSocketUpgradeFilter.class));
+
+        // Test we can upgrade to websocket and send a message.
+        URI uri = URI.create("ws://localhost:" + connector.getLocalPort() + "/filterPath");
+        EventSocket socket = new EventSocket();
+        CompletableFuture<Session> connect = client.connect(socket, uri);
+        try (Session session = connect.get(5, TimeUnit.SECONDS))
+        {
+            session.getRemote().sendString("hello world");
+        }
+        assertTrue(socket.closeLatch.await(10, TimeUnit.SECONDS));
+
+        String msg = socket.textMessages.poll();
+        assertThat(msg, is("hello world"));
+    }
+
     @Test
     public void testLazyWebSocketUpgradeFilter() throws Exception
     {
+        start(null, null);
+
         // JettyWebSocketServerContainer has already been created.
         JettyWebSocketServerContainer container = JettyWebSocketServerContainer.getContainer(contextHandler.getServletContext());
         assertNotNull(container);
@@ -83,6 +127,47 @@ public void testLazyWebSocketUpgradeFilter() throws Exception
         // After mapping is added we have an UpgradeFilter.
         container.addMapping("/", EchoSocket.class);
         assertThat(contextHandler.getServletHandler().getFilters().length, is(1));
+        FilterHolder filterHolder = contextHandler.getServletHandler().getFilter("WebSocketUpgradeFilter");
+        assertNotNull(filterHolder);
+        assertThat(filterHolder.getState(), is(AbstractLifeCycle.STARTED));
+        assertThat(filterHolder.getFilter(), instanceOf(WebSocketUpgradeFilter.class));
+
+        // Test we can upgrade to websocket and send a message.
+        URI uri = URI.create("ws://localhost:" + connector.getLocalPort() + "/filterPath");
+        EventSocket socket = new EventSocket();
+        CompletableFuture<Session> connect = client.connect(socket, uri);
+        try (Session session = connect.get(5, TimeUnit.SECONDS))
+        {
+            session.getRemote().sendString("hello world");
+        }
+        assertTrue(socket.closeLatch.await(10, TimeUnit.SECONDS));
+
+        String msg = socket.textMessages.poll();
+        assertThat(msg, is("hello world"));
+    }
+
+    @Test
+    public void testWebSocketUpgradeFilterWhileStarting() throws Exception
+    {
+        start(new ServletHolder(new HttpServlet()
+        {
+            @Override
+            public void init()
+            {
+                JettyWebSocketServerContainer container = JettyWebSocketServerContainer.getContainer(getServletContext());
+                if (container == null)
+                    throw new IllegalArgumentException("Missing JettyWebSocketServerContainer");
+
+                container.addMapping("/", EchoSocket.class);
+            }
+        }));
+
+        // After mapping is added we have an UpgradeFilter.
+        assertThat(contextHandler.getServletHandler().getFilters().length, is(1));
+        FilterHolder filterHolder = contextHandler.getServletHandler().getFilter("WebSocketUpgradeFilter");
+        assertNotNull(filterHolder);
+        assertThat(filterHolder.getState(), is(AbstractLifeCycle.STARTED));
+        assertThat(filterHolder.getFilter(), instanceOf(WebSocketUpgradeFilter.class));
 
         // Test we can upgrade to websocket and send a message.
         URI uri = URI.create("ws://localhost:" + connector.getLocalPort() + "/filterPath");