diff --git a/src/test/java/org/springframework/metrics/instrument/web/MockServerRequest.java b/src/test/java/org/springframework/metrics/instrument/web/MockServerRequest.java
index abaf29ead..e8ab9fd63 100644
--- a/src/test/java/org/springframework/metrics/instrument/web/MockServerRequest.java
+++ b/src/test/java/org/springframework/metrics/instrument/web/MockServerRequest.java
@@ -18,6 +18,7 @@
 import java.net.InetSocketAddress;
 import java.net.URI;
 import java.nio.charset.Charset;
+import java.security.Principal;
 import java.time.Instant;
 import java.time.ZoneId;
 import java.time.ZonedDateTime;
@@ -46,8 +47,6 @@
 import org.springframework.web.server.WebSession;
 
 /**
- * Mock implementation of {@link ServerRequest}.
- *
  * @author Arjen Poutsma
  */
 public class MockServerRequest implements ServerRequest {
@@ -68,11 +67,12 @@ public class MockServerRequest implements ServerRequest {
 
 	private final WebSession session;
 
+	private Principal principal;
 
 	private MockServerRequest(HttpMethod method, URI uri,
-			MockHeaders headers, Object body, Map<String, Object> attributes,
-			MultiValueMap<String, String> queryParams,
-			Map<String, String> pathVariables, WebSession session) {
+							  MockHeaders headers, Object body, Map<String, Object> attributes,
+							  MultiValueMap<String, String> queryParams,
+							  Map<String, String> pathVariables, WebSession session, Principal principal) {
 
 		this.method = method;
 		this.uri = uri;
@@ -82,6 +82,7 @@ private MockServerRequest(HttpMethod method, URI uri,
 		this.queryParams = queryParams;
 		this.pathVariables = pathVariables;
 		this.session = session;
+		this.principal = principal;
 	}
 
 
@@ -150,6 +151,10 @@ public Mono<WebSession> session() {
 		return Mono.justOrEmpty(this.session);
 	}
 
+	@Override
+	public Mono<? extends Principal> principal() {
+		return Mono.justOrEmpty(this.principal);
+	}
 
 	public static Builder builder() {
 		return new BuilderImpl();
@@ -180,6 +185,8 @@ public interface Builder {
 
 		Builder session(WebSession session);
 
+		Builder session(Principal principal);
+
 		MockServerRequest body(Object body);
 
 		MockServerRequest build();
@@ -204,6 +211,8 @@ private static class BuilderImpl implements Builder {
 
 		private WebSession session;
 
+		private Principal principal;
+
 		@Override
 		public Builder method(HttpMethod method) {
 			Assert.notNull(method, "'method' must not be null");
@@ -285,17 +294,26 @@ public Builder session(WebSession session) {
 			return this;
 		}
 
+		@Override
+		public Builder session(Principal principal) {
+			Assert.notNull(principal, "'principal' must not be null");
+			this.principal = principal;
+			return this;
+		}
+
 		@Override
 		public MockServerRequest body(Object body) {
 			this.body = body;
 			return new MockServerRequest(this.method, this.uri, this.headers, this.body,
-					this.attributes, this.queryParams, this.pathVariables, this.session);
+					this.attributes, this.queryParams, this.pathVariables, this.session,
+					this.principal);
 		}
 
 		@Override
 		public MockServerRequest build() {
 			return new MockServerRequest(this.method, this.uri, this.headers, null,
-					this.attributes, this.queryParams, this.pathVariables, this.session);
+					this.attributes, this.queryParams, this.pathVariables, this.session,
+					this.principal);
 		}
 	}