test: cleanup balancer switching tests (#5271)

clientconn.go

@@ -672,14 +672,14 @@ func (cc *ClientConn) updateResolverState(s resolver.State, err error) error {
 	cc.mu.Unlock()
 	if cbn != grpclbName {
 		// Filter any grpclb addresses since we don't have the grpclb balancer.
-		for i := 0; i < len(s.Addresses); {
-			if s.Addresses[i].Type == resolver.GRPCLB {
-				copy(s.Addresses[i:], s.Addresses[i+1:])
-				s.Addresses = s.Addresses[:len(s.Addresses)-1]
+		var addrs []resolver.Address
+		for _, addr := range s.Addresses {
+			if addr.Type == resolver.GRPCLB {
 				continue
 			}
-			i++
+			addrs = append(addrs, addr)
 		}
+		s.Addresses = addrs
 	}
 	uccsErr := bw.updateClientConnState(&balancer.ClientConnState{ResolverState: s, BalancerConfig: balCfg})
 	if ret == nil {

clientconn_state_transition_test.go

@@ -35,7 +35,10 @@ import (
 	"google.golang.org/grpc/resolver/manual"
 )
 
-const stateRecordingBalancerName = "state_recoding_balancer"
+const (
+	stateRecordingBalancerName = "state_recoding_balancer"
+	defaultTestTimeout         = 10 * time.Second
+)
 
 var testBalancerBuilder = newStateRecordingBalancerBuilder()
 

clientconn_test.go

@@ -40,9 +40,18 @@ import (
 	"google.golang.org/grpc/keepalive"
 	"google.golang.org/grpc/resolver"
 	"google.golang.org/grpc/resolver/manual"
+	"google.golang.org/grpc/serviceconfig"
 	"google.golang.org/grpc/testdata"
 )
 
+func parseCfg(r *manual.Resolver, s string) *serviceconfig.ParseResult {
+	scpr := r.CC.ParseServiceConfig(s)
+	if scpr.Err != nil {
+		panic(fmt.Sprintf("Error parsing config %q: %v", s, scpr.Err))
+	}
+	return scpr
+}
+
 func (s) TestDialWithTimeout(t *testing.T) {
 	lis, err := net.Listen("tcp", "localhost:0")
 	if err != nil {