HeaderServerInterceptorTest.java

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package io.grpc.examples.header;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;
import static org.mockito.Mockito.spy;
import static org.mockito.Mockito.verify;

import io.grpc.CallOptions;
import io.grpc.Channel;
import io.grpc.ClientCall;
import io.grpc.ClientInterceptor;
import io.grpc.ForwardingClientCall.SimpleForwardingClientCall;
import io.grpc.ManagedChannel;
import io.grpc.Metadata;
import io.grpc.MethodDescriptor;
import io.grpc.Server;
import io.grpc.ServerInterceptors;
import io.grpc.examples.helloworld.GreeterGrpc;
import io.grpc.examples.helloworld.GreeterGrpc.GreeterBlockingStub;
import io.grpc.examples.helloworld.GreeterGrpc.GreeterImplBase;
import io.grpc.examples.helloworld.HelloReply;
import io.grpc.examples.helloworld.HelloRequest;
import io.grpc.inprocess.InProcessChannelBuilder;
import io.grpc.inprocess.InProcessServerBuilder;
import io.grpc.stub.StreamObserver;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;
import org.mockito.ArgumentCaptor;

/**
 * Unit tests for {@link HeaderClientInterceptor}.
 * For demonstrating how to write gRPC unit test only.
 * Not intended to provide a high code coverage or to test every major usecase.
 *
 * <p>For basic unit test examples see {@link io.grpc.examples.helloworld.HelloWorldClientTest} and
 * {@link io.grpc.examples.helloworld.HelloWorldServerTest}.
 */
@RunWith(JUnit4.class)
public class HeaderServerInterceptorTest {
  private Server fakeServer;
  private ManagedChannel inProcessChannel;

  @Before
  public void setUp() throws Exception {
    String uniqueServerName = "fake server for " + getClass();
    GreeterImplBase greeterImplBase =
        new GreeterImplBase() {
          @Override
          public void sayHello(HelloRequest request, StreamObserver<HelloReply> responseObserver) {
            responseObserver.onNext(HelloReply.getDefaultInstance());
            responseObserver.onCompleted();
          }
        };
    fakeServer = InProcessServerBuilder.forName(uniqueServerName)
        .addService(ServerInterceptors.intercept(greeterImplBase, new HeaderServerInterceptor()))
        .directExecutor()
        .build()
        .start();
    inProcessChannel = InProcessChannelBuilder.forName(uniqueServerName).directExecutor().build();
  }

  @After
  public void tearDown() {
    inProcessChannel.shutdownNow();
    fakeServer.shutdownNow();
  }

  @Test
  public void serverHeaderDeliveredToClient() {
    class SpyingClientInterceptor implements ClientInterceptor {
      ClientCall.Listener<?> spyListener;

      @Override
      public <ReqT, RespT> ClientCall<ReqT, RespT> interceptCall(
          MethodDescriptor<ReqT, RespT> method, CallOptions callOptions, Channel next) {
        return new SimpleForwardingClientCall<ReqT, RespT>(next.newCall(method, callOptions)) {
          @Override
          public void start(Listener<RespT> responseListener, Metadata headers) {
            spyListener = responseListener = spy(responseListener);
            super.start(responseListener, headers);
          }
        };
      }
    }

    SpyingClientInterceptor clientInterceptor = new SpyingClientInterceptor();
    GreeterBlockingStub blockingStub =
        GreeterGrpc.newBlockingStub(inProcessChannel).withInterceptors(clientInterceptor);
    ArgumentCaptor<Metadata> metadataCaptor = ArgumentCaptor.forClass(Metadata.class);

    blockingStub.sayHello(HelloRequest.getDefaultInstance());

    assertNotNull(clientInterceptor.spyListener);
    verify(clientInterceptor.spyListener).onHeaders(metadataCaptor.capture());
    assertEquals(
        "customRespondValue",
        metadataCaptor.getValue().get(HeaderServerInterceptor.CUSTOM_HEADER_KEY));
  }
}