Method TestBalancerSwitch_grpclbNotRegistered

test/balancer_switching_test.go:331–376

TestBalancerSwitch_grpclbNotRegistered tests the scenario where the grpclb balancer is not registered. Verifies that the ClientConn falls back to the default LB policy or the LB policy specified in the service config, and that addresses of type "grpclb" are filtered out.

(t *testing.T)

// default LB policy or the LB policy specified in the service config, and that
// addresses of type "grpclb" are filtered out.
func (s) TestBalancerSwitch_grpclbNotRegistered(t *testing.T) {
	// Unregister the grpclb balancer builder for the duration of this test.
	grpclbBuilder := balancer.Get("grpclb")
	internal.BalancerUnregister(grpclbBuilder.Name())
	defer balancer.Register(grpclbBuilder)

	backends, cleanup := startBackendsForBalancerSwitch(t)
	defer cleanup()
	addrs := stubBackendsToResolverAddrs(backends)

	r := manual.NewBuilderWithScheme("whatever")
	cc, err := grpc.NewClient(r.Scheme()+":///test.server", grpc.WithTransportCredentials(insecure.NewCredentials()), grpc.WithResolvers(r))
	if err != nil {
		t.Fatalf("grpc.NewClient() failed: %v", err)
	}
	defer cc.Close()
	cc.Connect()

	// Push a resolver update which contains a bunch of stub server backends and a
	// grpclb server address. The latter should get the ClientConn to try and
	// apply the grpclb policy. But since grpclb is not registered, it should
	// fallback to the default LB policy which is pick_first. The ClientConn is
	// also expected to filter out the grpclb address when sending the addresses
	// list for pick_first.
	grpclbAddr := []resolver.Address{{Addr: "non-existent-grpclb-server-address"}}
	grpclbConfig := parseServiceConfig(t, r, `{"loadBalancingPolicy": "grpclb"}`)
	state := resolver.State{ServiceConfig: grpclbConfig, Addresses: addrs}
	r.UpdateState(grpclbstate.Set(state, &grpclbstate.State{BalancerAddresses: grpclbAddr}))
	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
	defer cancel()
	if err := pfutil.CheckRPCsToBackend(ctx, cc, addrs[0]); err != nil {
		t.Fatalf("Pick_first backend readiness check failed: %v", err)
	}

	// Push a resolver update with the same addresses, but with a service config
	// specifying "round_robin". The ClientConn is expected to filter out the
	// grpclb address when sending the addresses list to round_robin.
	r.UpdateState(resolver.State{
		Addresses:     addrs,
		ServiceConfig: parseServiceConfig(t, r, rrServiceConfig),
	})
	client := testgrpc.NewTestServiceClient(cc)
	if err := rrutil.CheckRoundRobinRPCs(ctx, client, addrs); err != nil {
		t.Fatalf("Round robin RPCs failed: %v", err)
	}
}

// TestBalancerSwitch_OldBalancerCallsShutdownInClose tests the scenario where
// the balancer being switched out calls Shutdown() in its Close()