diff --git a/runners/portability/java/src/test/java/org/apache/beam/runners/portability/ExternalWorkerServiceTest.java b/runners/portability/java/src/test/java/org/apache/beam/runners/portability/ExternalWorkerServiceTest.java
new file mode 100644
index 0000000..8997cd2
--- /dev/null
+++ b/runners/portability/java/src/test/java/org/apache/beam/runners/portability/ExternalWorkerServiceTest.java
@@ -0,0 +1,61 @@
+/*
+ * 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.beam.runners.portability;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+
+import org.apache.beam.model.fnexecution.v1.BeamFnApi.StartWorkerRequest;
+import org.apache.beam.model.fnexecution.v1.BeamFnApi.StartWorkerResponse;
+import org.apache.beam.model.fnexecution.v1.BeamFnApi.StopWorkerRequest;
+import org.apache.beam.model.fnexecution.v1.BeamFnApi.StopWorkerResponse;
+import org.apache.beam.sdk.options.PipelineOptions;
+import org.apache.beam.sdk.options.PipelineOptionsFactory;
+import org.apache.beam.vendor.grpc.v1p26p0.io.grpc.stub.StreamObserver;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public class ExternalWorkerServiceTest {
+
+  @Test
+  public void startWorker() {
+    PipelineOptions options = PipelineOptionsFactory.create();
+    StartWorkerRequest request = StartWorkerRequest.newBuilder().build();
+    StreamObserver<StartWorkerResponse> responseObserver = mock(StreamObserver.class);
+    ExternalWorkerService service = new ExternalWorkerService(options);
+    service.startWorker(request, responseObserver);
+
+    verify(responseObserver).onNext(any(StartWorkerResponse.class));
+    verify(responseObserver).onCompleted();
+  }
+
+  @Test
+  public void stopWorker() {
+    PipelineOptions options = PipelineOptionsFactory.create();
+    StopWorkerRequest request = StopWorkerRequest.newBuilder().build();
+    StreamObserver<StopWorkerResponse> responseObserver = mock(StreamObserver.class);
+    ExternalWorkerService service = new ExternalWorkerService(options);
+    service.stopWorker(request, responseObserver);
+
+    verify(responseObserver).onNext(any(StopWorkerResponse.class));
+    verify(responseObserver).onCompleted();
+  }
+}