diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/config/WebSocketMessageBrokerStats.java b/spring-websocket/src/main/java/org/springframework/web/socket/config/WebSocketMessageBrokerStats.java
index 6b35ac0398..7adf7c3fe7 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/config/WebSocketMessageBrokerStats.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/config/WebSocketMessageBrokerStats.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,7 @@ import java.time.Duration;
 import java.time.Instant;
 import java.util.concurrent.Executor;
 import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 
 import org.apache.commons.logging.Log;
@@ -49,6 +50,7 @@ import org.springframework.web.socket.messaging.SubProtocolWebSocketHandler;
  * the {@link org.springframework.jmx.export.MBeanExporter MBeanExporter}.
  *
  * @author Rossen Stoyanchev
+ * @author Sam Brannen
  * @since 4.1
  */
 public class WebSocketMessageBrokerStats {
@@ -174,16 +176,14 @@ public class WebSocketMessageBrokerStats {
 	 * Get stats about the executor processing incoming messages from WebSocket clients.
 	 */
 	public String getClientInboundExecutorStatsInfo() {
-		return (this.inboundChannelExecutor != null ?
-				getExecutorStatsInfo(this.inboundChannelExecutor) : "null");
+		return getExecutorStatsInfo(this.inboundChannelExecutor);
 	}
 
 	/**
 	 * Get stats about the executor processing outgoing messages to WebSocket clients.
 	 */
 	public String getClientOutboundExecutorStatsInfo() {
-		return (this.outboundChannelExecutor != null ?
-				getExecutorStatsInfo(this.outboundChannelExecutor) : "null");
+		return getExecutorStatsInfo(this.outboundChannelExecutor);
 	}
 
 	/**
@@ -197,16 +197,31 @@ public class WebSocketMessageBrokerStats {
 			return getExecutorStatsInfo(((ThreadPoolTaskScheduler) this.sockJsTaskScheduler)
 					.getScheduledThreadPoolExecutor());
 		}
-		else {
-			return "unknown";
-		}
+		return "unknown";
 	}
 
-	private String getExecutorStatsInfo(Executor executor) {
-		executor = executor instanceof ThreadPoolTaskExecutor ?
-				((ThreadPoolTaskExecutor) executor).getThreadPoolExecutor() : executor;
-		String str = executor.toString();
-		return str.substring(str.indexOf("pool"), str.length() - 1);
+	private String getExecutorStatsInfo(@Nullable Executor executor) {
+		if (executor == null) {
+			return "null";
+		}
+
+		if (executor instanceof ThreadPoolTaskExecutor) {
+			executor = ((ThreadPoolTaskExecutor) executor).getThreadPoolExecutor();
+		}
+
+		if (executor instanceof ThreadPoolExecutor) {
+			// It is assumed that the implementation of toString() in ThreadPoolExecutor
+			// generates text that ends similar to the following:
+			// pool size = #, active threads = #, queued tasks = #, completed tasks = #]
+			String str = executor.toString();
+			int indexOfPool = str.indexOf("pool");
+			if (indexOfPool != -1) {
+				// (length - 1) omits the trailing "]"
+				return str.substring(indexOfPool, str.length() - 1);
+			}
+		}
+
+		return "unknown";
 	}
 
 	@Override
diff --git a/spring-websocket/src/test/java/org/springframework/web/socket/config/WebSocketMessageBrokerStatsTests.java b/spring-websocket/src/test/java/org/springframework/web/socket/config/WebSocketMessageBrokerStatsTests.java
new file mode 100644
index 0000000000..324dc4942d
--- /dev/null
+++ b/spring-websocket/src/test/java/org/springframework/web/socket/config/WebSocketMessageBrokerStatsTests.java
@@ -0,0 +1,92 @@
+/*
+ * Copyright 2002-2021 the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      https://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.springframework.web.socket.config;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.core.task.TaskExecutor;
+import org.springframework.scheduling.TaskScheduler;
+import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
+import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Unit tests for {@link WebSocketMessageBrokerStats}.
+ *
+ * @author Sam Brannen
+ * @since 5.3.10
+ * @see org.springframework.web.socket.config.annotation.WebSocketMessageBrokerConfigurationSupportTests
+ */
+class WebSocketMessageBrokerStatsTests {
+
+	private final WebSocketMessageBrokerStats stats = new WebSocketMessageBrokerStats();
+
+	@Test
+	void nullValues() {
+		String expected = "WebSocketSession[null], stompSubProtocol[null], stompBrokerRelay[null], " +
+				"inboundChannel[null], outboundChannel[null], sockJsScheduler[null]";
+		assertThat(stats).hasToString(expected);
+	}
+
+	@Test
+	void inboundAndOutboundChannelsWithThreadPoolTaskExecutor() {
+		ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
+		executor.afterPropertiesSet();
+
+		stats.setInboundChannelExecutor(executor);
+		stats.setOutboundChannelExecutor(executor);
+
+		assertThat(stats.getClientInboundExecutorStatsInfo()).as("inbound channel stats")
+			.isEqualTo("pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 0");
+		assertThat(stats.getClientOutboundExecutorStatsInfo()).as("outbound channel stats")
+			.isEqualTo("pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 0");
+	}
+
+	@Test
+	void inboundAndOutboundChannelsWithMockedTaskExecutor() {
+		TaskExecutor executor = mock(TaskExecutor.class);
+
+		stats.setInboundChannelExecutor(executor);
+		stats.setOutboundChannelExecutor(executor);
+
+		assertThat(stats.getClientInboundExecutorStatsInfo()).as("inbound channel stats").isEqualTo("unknown");
+		assertThat(stats.getClientOutboundExecutorStatsInfo()).as("outbound channel stats").isEqualTo("unknown");
+	}
+
+	@Test
+	void sockJsTaskSchedulerWithThreadPoolTaskScheduler() {
+		ThreadPoolTaskScheduler scheduler = new ThreadPoolTaskScheduler();
+		scheduler.afterPropertiesSet();
+
+		stats.setSockJsTaskScheduler(scheduler);
+
+		assertThat(stats.getSockJsTaskSchedulerStatsInfo())
+			.isEqualTo("pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 0");
+	}
+
+	@Test
+	void sockJsTaskSchedulerWithMockedTaskScheduler() {
+		TaskScheduler scheduler = mock(TaskScheduler.class);
+
+		stats.setSockJsTaskScheduler(scheduler);
+
+		assertThat(stats.getSockJsTaskSchedulerStatsInfo()).isEqualTo("unknown");
+	}
+
+}