fix: uses unimplemented server if impl is nil (#1690)

Author: MStreet3

pkg/loop/internal/core/services/gateway/gateway_connector.go

@@ -127,7 +127,7 @@ func (s GatewayConnectorServer) AddHandler(ctx context.Context, req *pb.AddHandl
 		return nil, fmt.Errorf("failed to dial handler: %d: %w", req.HandlerId, err)
 	}
 	client := NewGatewayConnectorHandlerClient(conn)
-	err = s.impl.AddHandler(ctx, req.Methods, client)
+	err = s.getImpl().AddHandler(ctx, req.Methods, client)
 	if err != nil {
 		return nil, fmt.Errorf("failed to add handler: %d: %w", req.HandlerId, err)
 	}
@@ -140,38 +140,48 @@ func (s GatewayConnectorServer) SendToGateway(ctx context.Context, req *pb.SendM
 	if err != nil {
 		return nil, fmt.Errorf("failed to decode response: %w", err)
 	}
-	if err := s.impl.SendToGateway(ctx, req.GatewayId, &resp); err != nil {
+	if err := s.getImpl().SendToGateway(ctx, req.GatewayId, &resp); err != nil {
 		return nil, fmt.Errorf("failed to send message to gateway: %s: %w", req.GatewayId, err)
 	}
 	return &emptypb.Empty{}, nil
 }
+
 func (s GatewayConnectorServer) SignMessage(ctx context.Context, req *pb.SignMessageRequest) (*pb.SignMessageReply, error) {
-	signature, err := s.impl.SignMessage(ctx, req.Message)
+	signature, err := s.getImpl().SignMessage(ctx, req.Message)
 	if err != nil {
 		return nil, fmt.Errorf("failed to sign message: %w", err)
 	}
 	return &pb.SignMessageReply{
 		Signature: signature,
 	}, nil
 }
+
 func (s GatewayConnectorServer) GatewayIDs(ctx context.Context, _ *emptypb.Empty) (*pb.GatewayIDsReply, error) {
-	gatewayIDs, err := s.impl.GatewayIDs(ctx)
+	gatewayIDs, err := s.getImpl().GatewayIDs(ctx)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get gateway IDs: %w", err)
 	}
 	return &pb.GatewayIDsReply{GatewayIds: gatewayIDs}, nil
 }
 
 func (s GatewayConnectorServer) DonID(ctx context.Context, _ *emptypb.Empty) (*pb.DonIDReply, error) {
-	donID, err := s.impl.DonID(ctx)
+	donID, err := s.getImpl().DonID(ctx)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get DON ID: %w", err)
 	}
 	return &pb.DonIDReply{DonId: donID}, nil
 }
+
 func (s GatewayConnectorServer) AwaitConnection(ctx context.Context, req *pb.GatewayIDRequest) (*emptypb.Empty, error) {
-	if err := s.impl.AwaitConnection(ctx, req.GatewayId); err != nil {
+	if err := s.getImpl().AwaitConnection(ctx, req.GatewayId); err != nil {
 		return nil, fmt.Errorf("failed to await connection to gateway: %s: %w", req.GatewayId, err)
 	}
 	return &emptypb.Empty{}, nil
 }
+
+func (s GatewayConnectorServer) getImpl() core.GatewayConnector {
+	if s.impl == nil {
+		return &core.UnimplementedGatewayConnector{}
+	}
+	return s.impl
+}

pkg/loop/internal/core/services/gateway/gateway_connector_test.go

@@ -0,0 +1,46 @@
+package gateway_test
+
+import (
+	"testing"
+
+	"github.com/smartcontractkit/chainlink-common/pkg/logger"
+	"github.com/smartcontractkit/chainlink-common/pkg/loop/internal/core/services/gateway"
+	loopnet "github.com/smartcontractkit/chainlink-common/pkg/loop/internal/net"
+	loopnettest "github.com/smartcontractkit/chainlink-common/pkg/loop/internal/net/test"
+	pb "github.com/smartcontractkit/chainlink-common/pkg/loop/internal/pb/gatewayconnector"
+	"github.com/smartcontractkit/chainlink-common/pkg/types/core"
+
+	"github.com/stretchr/testify/require"
+)
+
+func Test_GatewayConnectorServer(t *testing.T) {
+	t.Run("calling AddHandler with a nil connector client does not panic", func(t *testing.T) {
+		var (
+			lggr      = logger.Test(t)
+			ctx       = t.Context()
+			handlerID = uint32(0)
+			broker    = &loopnettest.Broker{T: t}
+			brokerCfg = loopnet.BrokerConfig{Logger: lggr, StopCh: make(chan struct{})}
+			brokerExt = &loopnet.BrokerExt{
+				Broker:       broker,
+				BrokerConfig: brokerCfg,
+			}
+		)
+
+		// allocate a listener for the handler
+		_, err := broker.Accept(handlerID)
+		require.NoError(t, err)
+
+		// create instance of connector server with empty GatewayConnector
+		var gc core.GatewayConnector
+		gcs := gateway.NewGatewayConnectorServer(brokerExt, gc)
+
+		// assert that call does not panic, yet errors
+		res, err := gcs.AddHandler(ctx, &pb.AddHandlerRequest{
+			HandlerId: handlerID,
+		})
+		require.Error(t, err)
+		require.ErrorContains(t, err, "not implemented")
+		require.Nil(t, res)
+	})
+}