chore: add showcase test for server-side with gRPC transport

showcase/gapic-showcase/src/test/java/com/google/showcase/v1beta1/it/ITServerSideStreaming.java

@@ -0,0 +1,101 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * 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 com.google.showcase.v1beta1.it;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertThrows;
+
+import com.google.api.gax.core.NoCredentialsProvider;
+import com.google.api.gax.grpc.InstantiatingGrpcChannelProvider;
+import com.google.api.gax.rpc.CancelledException;
+import com.google.api.gax.rpc.ServerStream;
+import com.google.api.gax.rpc.StatusCode;
+import com.google.common.collect.ImmutableList;
+import com.google.rpc.Status;
+import com.google.showcase.v1beta1.EchoClient;
+import com.google.showcase.v1beta1.EchoResponse;
+import com.google.showcase.v1beta1.EchoSettings;
+import com.google.showcase.v1beta1.ExpandRequest;
+import io.grpc.ManagedChannelBuilder;
+import java.io.IOException;
+import java.security.GeneralSecurityException;
+import java.util.ArrayList;
+import java.util.Iterator;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+public class ITServerSideStreaming {
+
+  private EchoClient grpcClient;
+
+  @Before
+  public void createClients() throws IOException, GeneralSecurityException {
+    // Create gRPC Echo Client
+    EchoSettings grpcEchoSettings =
+        EchoSettings.newBuilder()
+            .setCredentialsProvider(NoCredentialsProvider.create())
+            .setTransportChannelProvider(
+                InstantiatingGrpcChannelProvider.newBuilder()
+                    .setChannelConfigurator(ManagedChannelBuilder::usePlaintext)
+                    .build())
+            .build();
+    grpcClient = EchoClient.create(grpcEchoSettings);
+  }
+
+  @After
+  public void destroyClient() {
+    grpcClient.close();
+  }
+
+  @Test
+  public void testGrpc_receiveStreamedContent() {
+    String content = "The rain in Spain stays mainly on the plain!";
+    ServerStream<EchoResponse> responseStream =
+        grpcClient.expandCallable().call(ExpandRequest.newBuilder().setContent(content).build());
+    ArrayList<String> responses = new ArrayList<>();
+    for (EchoResponse response : responseStream) {
+      responses.add(response.getContent());
+    }
+
+    assertThat(responses)
+        .containsExactlyElementsIn(
+            ImmutableList.of(
+                "The", "rain", "in", "Spain", "stays", "mainly", "on", "the", "plain!"))
+        .inOrder();
+  }
+
+  @Test
+  public void testGrpc_serverError_receiveErrorAfterLastWordInStream() {
+    String content = "The rain in Spain";
+    Status cancelledStatus =
+        Status.newBuilder().setCode(StatusCode.Code.CANCELLED.ordinal()).build();
+    ServerStream<EchoResponse> responseStream =
+        grpcClient
+            .expandCallable()
+            .call(ExpandRequest.newBuilder().setContent(content).setError(cancelledStatus).build());
+    Iterator<EchoResponse> echoResponseIterator = responseStream.iterator();
+
+    assertThat(echoResponseIterator.next().getContent()).isEqualTo("The");
+    assertThat(echoResponseIterator.next().getContent()).isEqualTo("rain");
+    assertThat(echoResponseIterator.next().getContent()).isEqualTo("in");
+    assertThat(echoResponseIterator.next().getContent()).isEqualTo("Spain");
+    CancelledException cancelledException =
+        assertThrows(CancelledException.class, echoResponseIterator::next);
+    assertThat(cancelledException.getStatusCode().getCode()).isEqualTo(StatusCode.Code.CANCELLED);
+  }
+}