Method TestGRPCLB_FallBackWithNoServerAddress

balancer/grpclb/grpclb_test.go:963–1063

TestGRPCLB_FallBackWithNoServerAddress tests the fallback case where no backend addresses are returned by the remote balancer.

(t *testing.T)

// TestGRPCLB_FallBackWithNoServerAddress tests the fallback case where no
// backend addresses are returned by the remote balancer.
func (s) TestGRPCLB_FallBackWithNoServerAddress(t *testing.T) {
	resolveNowCh := testutils.NewChannel()
	r := manual.NewBuilderWithScheme("whatever")
	r.ResolveNowCallback = func(resolver.ResolveNowOptions) {
		ctx, cancel := context.WithTimeout(context.Background(), defaultTestShortTimeout)
		defer cancel()
		if err := resolveNowCh.SendContext(ctx, nil); err != nil {
			t.Error("timeout when attempting to send on resolverNowCh")
		}
	}

	// Start a remote balancer and a backend. Don't push the backend address to
	// the remote balancer yet.
	tss, cleanup, err := startBackendsAndRemoteLoadBalancer(t, 1, "", nil)
	if err != nil {
		t.Fatalf("failed to create new load balancer: %v", err)
	}
	defer cleanup()
	sl := &lbpb.ServerList{
		Servers: []*lbpb.Server{
			{
				IpAddress:        tss.beIPs[0].AsSlice(),
				Port:             int32(tss.bePorts[0]),
				LoadBalanceToken: lbToken,
			},
		},
	}

	// Start a standalone backend for fallback.
	beLis, err := net.Listen("tcp", "localhost:0")
	if err != nil {
		t.Fatalf("Failed to listen %v", err)
	}
	defer beLis.Close()
	standaloneBEs := startBackends(t, beServerName, true, beLis)
	defer stopBackends(standaloneBEs)

	dopts := []grpc.DialOption{
		grpc.WithResolvers(r),
		grpc.WithTransportCredentials(&serverNameCheckCreds{}),
		grpc.WithContextDialer(fakeNameDialer),
	}
	cc, err := grpc.NewClient(r.Scheme()+":///"+beServerName, dopts...)
	if err != nil {
		t.Fatalf("Failed to create a client for the backend %v", err)
	}
	defer cc.Close()
	cc.Connect()
	testC := testgrpc.NewTestServiceClient(cc)

	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
	defer cancel()
	for i := 0; i < 2; i++ {
		// Send an update with only backend address. grpclb should enter
		// fallback and use the fallback backend.
		r.UpdateState(resolver.State{
			Addresses:     []resolver.Address{{Addr: beLis.Addr().String()}},
			ServiceConfig: r.CC().ParseServiceConfig(grpclbConfig),