core/src/test/java/io/grpc/PickFirstBalancerTest.java

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package io.grpc;

import static org.junit.Assert.assertSame;
import static org.mockito.Matchers.any;
import static org.mockito.Matchers.eq;
import static org.mockito.Mockito.never;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.verifyNoMoreInteractions;
import static org.mockito.Mockito.when;

import com.google.common.base.Supplier;
import com.google.common.collect.Lists;

import io.grpc.TransportManager.InterimTransport;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;
import org.mockito.ArgumentCaptor;
import org.mockito.Captor;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;

import java.net.SocketAddress;
import java.util.List;

/** Unit test for {@link PickFirstBalancerFactory}. */
@RunWith(JUnit4.class)
public class PickFirstBalancerTest {
  private LoadBalancer<Transport> loadBalancer;

  private List<ResolvedServerInfoGroup> servers;
  private EquivalentAddressGroup addressGroup;

  @Mock private TransportManager<Transport> mockTransportManager;
  @Mock private Transport mockTransport;
  @Mock private InterimTransport<Transport> mockInterimTransport;
  @Mock private Transport mockInterimTransportAsTransport;
  @Captor private ArgumentCaptor<Supplier<Transport>> transportSupplierCaptor;

  @Before
  public void setUp() {
    MockitoAnnotations.initMocks(this);
    loadBalancer = PickFirstBalancerFactory.getInstance().newLoadBalancer(
        "fakeservice", mockTransportManager);
    servers = Lists.newArrayList();
    List<ResolvedServerInfo> resolvedServerInfoList = Lists.newArrayList();
    for (int i = 0; i < 3; i++) {
      resolvedServerInfoList.add(new ResolvedServerInfo(new FakeSocketAddress("server" + i)));
    }
    ResolvedServerInfoGroup resolvedServerInfoGroup = ResolvedServerInfoGroup.builder().addAll(
        resolvedServerInfoList).build();
    servers.add(resolvedServerInfoGroup);
    addressGroup = resolvedServerInfoGroup.toEquivalentAddressGroup();
    when(mockTransportManager.getTransport(eq(addressGroup))).thenReturn(mockTransport);
    when(mockTransportManager.createInterimTransport()).thenReturn(mockInterimTransport);
    when(mockInterimTransport.transport()).thenReturn(mockInterimTransportAsTransport);
  }

  @Test
  public void pickBeforeResolved() throws Exception {
    Transport t1 = loadBalancer.pickTransport(null);
    Transport t2 = loadBalancer.pickTransport(null);
    assertSame(mockInterimTransportAsTransport, t1);
    assertSame(mockInterimTransportAsTransport, t2);
    verify(mockTransportManager).createInterimTransport();
    verify(mockTransportManager, never()).getTransport(any(EquivalentAddressGroup.class));
    verify(mockInterimTransport, times(2)).transport();

    loadBalancer.handleResolvedAddresses(servers, Attributes.EMPTY);
    verify(mockInterimTransport).closeWithRealTransports(transportSupplierCaptor.capture());
    for (int i = 0; i < 2; i++) {
      assertSame(mockTransport, transportSupplierCaptor.getValue().get());
    }
    verify(mockTransportManager, times(2)).getTransport(eq(addressGroup));
    verifyNoMoreInteractions(mockTransportManager);
    verifyNoMoreInteractions(mockInterimTransport);
  }

  @Test
  public void pickBeforeNameResolutionError() {
    Transport t1 = loadBalancer.pickTransport(null);
    Transport t2 = loadBalancer.pickTransport(null);
    assertSame(mockInterimTransportAsTransport, t1);
    assertSame(mockInterimTransportAsTransport, t2);
    verify(mockTransportManager).createInterimTransport();
    verify(mockTransportManager, never()).getTransport(any(EquivalentAddressGroup.class));
    verify(mockInterimTransport, times(2)).transport();

    loadBalancer.handleNameResolutionError(Status.UNAVAILABLE);
    verify(mockInterimTransport).closeWithError(any(Status.class));
    // Ensure a shutdown after error closes without incident
    loadBalancer.shutdown();
    // Ensure a name resolution error after shutdown does nothing
    loadBalancer.handleNameResolutionError(Status.UNAVAILABLE);
    verifyNoMoreInteractions(mockInterimTransport);
  }

  @Test
  public void pickBeforeShutdown() {
    Transport t1 = loadBalancer.pickTransport(null);
    Transport t2 = loadBalancer.pickTransport(null);
    assertSame(mockInterimTransportAsTransport, t1);
    assertSame(mockInterimTransportAsTransport, t2);
    verify(mockTransportManager).createInterimTransport();
    verify(mockTransportManager, never()).getTransport(any(EquivalentAddressGroup.class));
    verify(mockInterimTransport, times(2)).transport();

    loadBalancer.shutdown();
    verify(mockInterimTransport).closeWithError(any(Status.class));
    // Ensure double shutdown just returns immediately without closing again.
    loadBalancer.shutdown();
    verifyNoMoreInteractions(mockInterimTransport);
  }

  @Test
  public void pickAfterResolved() throws Exception {
    loadBalancer.handleResolvedAddresses(servers, Attributes.EMPTY);
    Transport t = loadBalancer.pickTransport(null);
    assertSame(mockTransport, t);
    verify(mockTransportManager).getTransport(addressGroup);
    verifyNoMoreInteractions(mockTransportManager);
  }

  private static class FakeSocketAddress extends SocketAddress {
    final String name;

    FakeSocketAddress(String name) {
      this.name = name;
    }

    @Override
    public String toString() {
      return "FakeSocketAddress-" + name;
    }
  }

  private static class Transport {}
}