diff --git a/oauth2_http/javatests/com/google/auth/oauth2/UserCredentialsTest.java b/oauth2_http/javatests/com/google/auth/oauth2/UserCredentialsTest.java
index 92e8ebe73..037054ea6 100644
--- a/oauth2_http/javatests/com/google/auth/oauth2/UserCredentialsTest.java
+++ b/oauth2_http/javatests/com/google/auth/oauth2/UserCredentialsTest.java
@@ -40,6 +40,7 @@
 
 import com.google.api.client.json.GenericJson;
 import com.google.api.client.util.Clock;
+import com.google.auth.RequestMetadataCallback;
 import com.google.auth.TestUtils;
 import com.google.auth.http.AuthHttpConstants;
 import com.google.auth.oauth2.GoogleCredentialsTest.MockHttpTransportFactory;
@@ -56,6 +57,7 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.atomic.AtomicBoolean;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -622,6 +624,41 @@ public void saveAndRestoreUserCredential_saveAndRestored_throws() throws IOExcep
     assertEquals(userCredentials.getRefreshToken(), restoredCredentials.getRefreshToken());
   }
 
+  @Test
+  public void getRequestMetadataWithCallback() throws IOException {
+    MockTokenServerTransportFactory transportFactory = new MockTokenServerTransportFactory();
+    transportFactory.transport.addClient(CLIENT_ID, CLIENT_SECRET);
+    transportFactory.transport.addRefreshToken(REFRESH_TOKEN, ACCESS_TOKEN);
+
+    UserCredentials userCredentials =
+        UserCredentials.newBuilder()
+            .setClientId(CLIENT_ID)
+            .setClientSecret(CLIENT_SECRET)
+            .setRefreshToken(REFRESH_TOKEN)
+            .setQuotaProjectId("my-quota-project-id")
+            .setHttpTransportFactory(transportFactory)
+            .build();
+    final Map<String, List<String>> plainMetadata = userCredentials.getRequestMetadata();
+    final AtomicBoolean success = new AtomicBoolean(false);
+    userCredentials.getRequestMetadata(
+        null,
+        null,
+        new RequestMetadataCallback() {
+          @Override
+          public void onSuccess(Map<String, List<String>> metadata) {
+            assertEquals(plainMetadata, metadata);
+            success.set(true);
+          }
+
+          @Override
+          public void onFailure(Throwable exception) {
+            fail("Should not throw a failure.");
+          }
+        });
+
+    assertTrue("Should have run onSuccess() callback", success.get());
+  }
+
   static GenericJson writeUserJson(
       String clientId, String clientSecret, String refreshToken, String quotaProjectId) {
     GenericJson json = new GenericJson();