diff --git a/amber/src/test/scala/org/apache/texera/web/resource/WebsocketPayloadSizeTunerSpec.scala b/amber/src/test/scala/org/apache/texera/web/resource/WebsocketPayloadSizeTunerSpec.scala
new file mode 100644
index 00000000000..dc4d7abda4e
--- /dev/null
+++ b/amber/src/test/scala/org/apache/texera/web/resource/WebsocketPayloadSizeTunerSpec.scala
@@ -0,0 +1,57 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.texera.web.resource
+
+import org.scalamock.scalatest.MockFactory
+import org.scalatest.flatspec.AnyFlatSpec
+import org.scalatest.matchers.should.Matchers
+
+import javax.servlet.{ServletContext, ServletContextEvent}
+import javax.websocket.server.ServerContainer
+
+class WebsocketPayloadSizeTunerSpec extends AnyFlatSpec with Matchers with MockFactory {
+
+  private def eventWith(container: ServerContainer): ServletContextEvent = {
+    val servletContext = mock[ServletContext]
+    (servletContext
+      .getAttribute(_: String))
+      .expects(classOf[ServerContainer].getName)
+      .returning(container)
+      .once()
+    new ServletContextEvent(servletContext)
+  }
+
+  "contextInitialized" should "look up the server container by its class name and tune both limits" in {
+    val maxKiB = 64
+    val container = mock[ServerContainer]
+    (container.setDefaultMaxTextMessageBufferSize(_: Int)).expects(maxKiB * 1024).once()
+    (container.setDefaultMaxBinaryMessageBufferSize(_: Int)).expects(maxKiB * 1024).once()
+
+    new WebsocketPayloadSizeTuner(maxKiB).contextInitialized(eventWith(container))
+  }
+
+  it should "convert a one-KiB payload limit to exactly 1024 bytes" in {
+    val container = mock[ServerContainer]
+    (container.setDefaultMaxTextMessageBufferSize(_: Int)).expects(1024).once()
+    (container.setDefaultMaxBinaryMessageBufferSize(_: Int)).expects(1024).once()
+
+    new WebsocketPayloadSizeTuner(1).contextInitialized(eventWith(container))
+  }
+}