diff --git a/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/PrincipalMethodArgumentResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/PrincipalMethodArgumentResolverTests.java
new file mode 100644
index 0000000000..0f9664aa40
--- /dev/null
+++ b/spring-messaging/src/test/java/org/springframework/messaging/simp/annotation/support/PrincipalMethodArgumentResolverTests.java
@@ -0,0 +1,76 @@
+/*
+ * Copyright 2002-2019 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.messaging.simp.annotation.support;
+
+import java.security.Principal;
+import java.util.Collections;
+import java.util.Optional;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.core.MethodParameter;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.handler.invocation.ResolvableMethod;
+import org.springframework.messaging.simp.SimpMessageHeaderAccessor;
+import org.springframework.messaging.support.GenericMessage;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Unit tests for {@link PrincipalMethodArgumentResolver}.
+ *
+ * @author Rossen Stoyanchev
+ * @author Johnny Lim
+ */
+public class PrincipalMethodArgumentResolverTests {
+
+	private final PrincipalMethodArgumentResolver resolver = new PrincipalMethodArgumentResolver();
+
+	private final ResolvableMethod testMethod = ResolvableMethod.on(getClass()).named("handle").build();
+
+
+	@Test
+	public void supportsParameter() {
+		assertThat(this.resolver.supportsParameter(this.testMethod.arg(Principal.class))).isTrue();
+		assertThat(this.resolver.supportsParameter(this.testMethod.arg(Optional.class, Principal.class))).isTrue();
+	}
+
+
+	@Test
+	public void resolverArgument() {
+		Principal user = () -> "Joe";
+		Message<String> message = new GenericMessage<>("Hello, world!",
+				Collections.singletonMap(SimpMessageHeaderAccessor.USER_HEADER, user));
+
+		MethodParameter param = this.testMethod.arg(Principal.class);
+		Object actual = this.resolver.resolveArgument(param, message);
+		assertThat(actual).isSameAs(user);
+
+		param = this.testMethod.arg(Optional.class, Principal.class);
+		actual = this.resolver.resolveArgument(param, message);
+		assertThat(Optional.class.isAssignableFrom(actual.getClass())).isTrue();
+		assertThat(((Optional<?>) actual).get()).isSameAs(user);
+	}
+
+
+	@SuppressWarnings("unused")
+	void handle(
+			Principal user,
+			Optional<Principal> optionalUser) {
+	}
+
+}
diff --git a/spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/PrincipalMethodArgumentResolverTests.java b/spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/PrincipalMethodArgumentResolverTests.java
index 4ad26e732e..e12ab79928 100644
--- a/spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/PrincipalMethodArgumentResolverTests.java
+++ b/spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/PrincipalMethodArgumentResolverTests.java
@@ -42,7 +42,7 @@ public class PrincipalMethodArgumentResolverTests {
 	private final PrincipalMethodArgumentResolver resolver =
 			new PrincipalMethodArgumentResolver(ReactiveAdapterRegistry.getSharedInstance());
 
-	private ResolvableMethod testMethod = ResolvableMethod.on(getClass()).named("handle").build();
+	private final ResolvableMethod testMethod = ResolvableMethod.on(getClass()).named("handle").build();
 
 
 	@Test