rpc/client: Add unit test for TLS handshake failure

Inspired by nspcc-dev/neofs-node#2561.

Signed-off-by: Leonard Lyubich <leonard@morphbits.io>

rpc/client/connect.go

@@ -31,7 +31,7 @@ func (c *Client) createGRPCClient(ctx context.Context) (err error) {
 
 var errInvalidEndpoint = errors.New("invalid endpoint options")
 
-func (c *Client) openGRPCConn(ctx context.Context) error {
+func (c *Client) openGRPCConn(ctx context.Context, extraDialOpts ...grpcstd.DialOption) error {
 	if c.conn != nil {
 		return nil
 	}
@@ -51,10 +51,10 @@ func (c *Client) openGRPCConn(ctx context.Context) error {
 	dialCtx, cancel := context.WithTimeout(ctx, c.dialTimeout)
 	var err error
 
-	c.conn, err = grpcstd.DialContext(dialCtx, c.addr,
+	c.conn, err = grpcstd.DialContext(dialCtx, c.addr, append([]grpcstd.DialOption{
 		grpcstd.WithTransportCredentials(creds),
 		grpcstd.WithBlock(),
-	)
+	}, extraDialOpts...)...)
 
 	cancel()
 

rpc/client/connect_test.go

@@ -0,0 +1,35 @@
+package client
+
+import (
+	"context"
+	"crypto/tls"
+	"net"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/test/bufconn"
+)
+
+func TestClient_Init(t *testing.T) {
+	t.Run("TLS handshake failure", func(t *testing.T) {
+		lis := bufconn.Listen(1024) // size does not matter in this test
+
+		srv := grpc.NewServer()
+		t.Cleanup(srv.Stop)
+		go func() { _ = srv.Serve(lis) }()
+
+		c := New(WithNetworkURIAddress("grpcs://any:54321", new(tls.Config))...)
+
+		ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
+		t.Cleanup(cancel)
+
+		err := c.openGRPCConn(ctx, grpc.WithContextDialer(func(ctx context.Context, s string) (net.Conn, error) {
+			return lis.DialContext(ctx)
+		}))
+		// error is not wrapped properly, so we can do nothing more to check it.
+		// Text from stdlib tls.Conn.HandshakeContext.
+		require.ErrorContains(t, err, "first record does not look like a TLS handshake")
+	})
+}