Method TestConfigUpdate_ChildPolicyChange

balancer/rls/balancer_test.go:424–515

TestConfigUpdate_ChildPolicyChange verifies that a child policy change is handled by closing the old balancer and creating a new one.

(t *testing.T)

// TestConfigUpdate_ChildPolicyChange verifies that a child policy change is
// handled by closing the old balancer and creating a new one.
func (s) TestConfigUpdate_ChildPolicyChange(t *testing.T) {
	// Start an RLS server and set the throttler to never throttle requests.
	rlsServer, _ := rlstest.SetupFakeRLSServer(t, nil)
	overrideAdaptiveThrottler(t, neverThrottlingThrottler())

	// Set up balancer callbacks.
	configsCh1 := make(chan *e2e.RLSChildPolicyConfig, 1)
	closeCh1 := make(chan struct{}, 1)
	bf := &e2e.BalancerFuncs{
		UpdateClientConnState: func(cfg *e2e.RLSChildPolicyConfig) error {
			configsCh1 <- cfg
			return nil
		},
		Close: func() {
			closeCh1 <- struct{}{}
		},
	}

	// Register an LB policy to act as the child policy for RLS LB policy.
	childPolicyName1 := "test-child-policy-1" + t.Name()
	e2e.RegisterRLSChildPolicy(childPolicyName1, bf)
	t.Logf("Registered child policy with name %q", childPolicyName1)

	// Build RLS service config with a dummy default target.
	const defaultBackend = "default-backend"
	rlsConfig := buildBasicRLSConfig(childPolicyName1, rlsServer.Address)
	rlsConfig.RouteLookupConfig.DefaultTarget = defaultBackend

	// Register a manual resolver and push the RLS service config through it.
	r := startManualResolverWithConfig(t, rlsConfig)

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

	// At this point, the RLS LB policy should have received its config, and
	// should have created a child policy for the default target.
	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
	defer cancel()
	wantCfg := &e2e.RLSChildPolicyConfig{Backend: defaultBackend}
	select {
	case <-ctx.Done():
		t.Fatal("Timed out when waiting for the first child policy to receive its config")
	case gotCfg := <-configsCh1:
		if !cmp.Equal(gotCfg, wantCfg) {
			t.Fatalf("First child policy received config %+v, want %+v", gotCfg, wantCfg)
		}
	}

	// Set up balancer callbacks for the second policy.
	configsCh2 := make(chan *e2e.RLSChildPolicyConfig, 1)
	bf = &e2e.BalancerFuncs{
		UpdateClientConnState: func(cfg *e2e.RLSChildPolicyConfig) error {
			configsCh2 <- cfg
			return nil