diff --git a/engine/libengine_test.go b/engine/libengine_test.go
new file mode 100644
index 000000000..32d41f6c5
--- /dev/null
+++ b/engine/libengine_test.go
@@ -0,0 +1,229 @@
+/*
+Real-time Online/Offline Charging System (OCS) for Telecom & ISP environments
+Copyright (C) ITsysCOM GmbH
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>
+*/
+
+package engine
+
+import (
+	"bytes"
+	"fmt"
+	"log"
+	"os"
+	"reflect"
+	"testing"
+
+	"github.com/cgrates/cgrates/config"
+	"github.com/cgrates/cgrates/utils"
+	"github.com/cgrates/ltcache"
+	"github.com/cgrates/rpcclient"
+)
+
+func TestLibengineNewRPCPoolNoAddress(t *testing.T) {
+	tmp := Cache
+	defer func() {
+		Cache = tmp
+	}()
+
+	connID := "connID"
+	intChan := make(chan rpcclient.ClientConnector)
+	defaultCfg := config.NewDefaultCGRConfig()
+	defaultCfg.RPCConns()[connID] = config.NewDfltRPCConn()
+	defaultCfg.RPCConns()[connID].Conns = []*config.RemoteHost{
+		{
+			ID:      connID,
+			Address: utils.EmptyString,
+		},
+	}
+	connCache := ltcache.NewCache(-1, 0, true, nil)
+
+	exp := &rpcclient.RPCPool{}
+	experr := rpcclient.ErrDisconnected
+	rcv, err := NewRPCPool("", "", "", "", defaultCfg.GeneralCfg().ConnectAttempts,
+		defaultCfg.GeneralCfg().Reconnects, defaultCfg.GeneralCfg().ConnectTimeout,
+		0, defaultCfg.RPCConns()[connID].Conns, intChan, false, nil, connID, connCache)
+
+	if err == nil || err != experr {
+		t.Fatalf("\nexpected: <%+v>, \nreceived: <%+v>", experr, err)
+	}
+
+	if !reflect.DeepEqual(rcv, exp) {
+		t.Errorf("\nexpected: <%+v>, \nreceived: <%+v>", exp, rcv)
+	}
+}
+
+func TestLibengineNewRPCPoolUnsupportedTransport(t *testing.T) {
+	tmp := Cache
+	defer func() {
+		Cache = tmp
+	}()
+
+	connID := "connID"
+	intChan := make(chan rpcclient.ClientConnector)
+	defaultCfg := config.NewDefaultCGRConfig()
+	defaultCfg.RPCConns()[connID] = config.NewDfltRPCConn()
+	defaultCfg.RPCConns()[connID].Conns = []*config.RemoteHost{
+		{
+			ID:        connID,
+			Address:   rpcclient.JSONrpc,
+			Transport: "invalid",
+		},
+	}
+	connCache := ltcache.NewCache(-1, 0, true, nil)
+
+	var exp *rpcclient.RPCPool
+	experr := fmt.Sprintf("Unsupported transport: <%s>",
+		defaultCfg.RPCConns()[connID].Conns[0].Transport)
+	rcv, err := NewRPCPool("", "", "", "", defaultCfg.GeneralCfg().ConnectAttempts,
+		defaultCfg.GeneralCfg().Reconnects, defaultCfg.GeneralCfg().ConnectTimeout,
+		0, defaultCfg.RPCConns()[connID].Conns, intChan, false, nil, connID, connCache)
+
+	if err == nil || err.Error() != experr {
+		t.Fatalf("\nexpected: <%+v>, \nreceived: <%+v>", experr, err)
+	}
+
+	if rcv != exp {
+		t.Errorf("\nexpected: <%+v>, \nreceived: <%+v>", exp, rcv)
+	}
+}
+
+func TestLibengineNewRPCClientSet(t *testing.T) {
+	exp := RPCClientSet{}
+	rcv := NewRPCClientSet()
+
+	if !reflect.DeepEqual(rcv, exp) {
+		t.Errorf("\nexpected: <%+v>, \nreceived: <%+v>", exp, rcv)
+	}
+}
+
+func TestLibengineAddInternalRPCClientSuccess(t *testing.T) {
+	s := RPCClientSet{}
+	name := "testName"
+	connChan := make(chan rpcclient.ClientConnector)
+
+	expClient, err := rpcclient.NewRPCClient(utils.EmptyString, utils.EmptyString, false,
+		utils.EmptyString, utils.EmptyString, utils.EmptyString,
+		config.CgrConfig().GeneralCfg().ConnectAttempts, config.CgrConfig().GeneralCfg().Reconnects,
+		config.CgrConfig().GeneralCfg().ConnectTimeout, config.CgrConfig().GeneralCfg().ReplyTimeout,
+		rpcclient.InternalRPC, connChan, true, nil)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+	exp := RPCClientSet{
+		"testName": expClient,
+	}
+	s.AddInternalRPCClient(name, connChan)
+
+	if !reflect.DeepEqual(s, exp) {
+		t.Errorf("\nexpected: <%+v>, \nreceived: <%+v>", exp, s)
+	}
+}
+
+func TestLibengineAddInternalRPCClientLoggerErr(t *testing.T) {
+	s := RPCClientSet{}
+	name := "testName"
+
+	utils.Logger.SetLogLevel(3)
+	utils.Logger.SetSyslog(nil)
+
+	var buf bytes.Buffer
+	log.SetOutput(&buf)
+	defer func() {
+		log.SetOutput(os.Stderr)
+	}()
+
+	exp := "CGRateS <> [ERROR] <InternalRPCSet> Error adding testName to the set: INTERNALLY_DISCONNECTED\n"
+	s.AddInternalRPCClient(name, nil)
+	rcv := buf.String()[20:]
+
+	if rcv != exp {
+		t.Errorf("\nexpected: <%+v>, \nreceived: <%+v>", exp, rcv)
+	}
+
+	utils.Logger.SetLogLevel(0)
+}
+
+func TestLibengineCallInvalidMethod(t *testing.T) {
+	s := RPCClientSet{
+		"testField": &rpcclient.RPCClient{},
+	}
+	method := "invalid"
+	args := "testArgs"
+	reply := "testReply"
+
+	experr := rpcclient.ErrUnsupporteServiceMethod
+	err := s.Call(method, args, reply)
+
+	if err == nil || err != experr {
+		t.Errorf("\nexpected: <%+v>, \nreceived: <%+v>", experr, err)
+	}
+}
+
+func TestLibengineCallMethodNotFound(t *testing.T) {
+	connChan := make(chan rpcclient.ClientConnector)
+	client, err := rpcclient.NewRPCClient(utils.EmptyString, utils.EmptyString, false,
+		utils.EmptyString, utils.EmptyString, utils.EmptyString,
+		config.CgrConfig().GeneralCfg().ConnectAttempts, config.CgrConfig().GeneralCfg().Reconnects,
+		config.CgrConfig().GeneralCfg().ConnectTimeout, config.CgrConfig().GeneralCfg().ReplyTimeout,
+		rpcclient.InternalRPC, connChan, true, nil)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	s := RPCClientSet{
+		"testField": client,
+	}
+	method := "APIerSv1.Ping"
+	args := "testArgs"
+	reply := "testReply"
+
+	experr := rpcclient.ErrUnsupporteServiceMethod
+	err = s.Call(method, args, reply)
+
+	if err == nil || err != experr {
+		t.Errorf("\nexpected: <%+v>, \nreceived: <%+v>", experr, err)
+	}
+}
+
+func TestLibengineCallNilArgument(t *testing.T) {
+	connChan := make(chan rpcclient.ClientConnector)
+	client, err := rpcclient.NewRPCClient(utils.EmptyString, utils.EmptyString, false,
+		utils.EmptyString, utils.EmptyString, utils.EmptyString,
+		config.CgrConfig().GeneralCfg().ConnectAttempts, config.CgrConfig().GeneralCfg().Reconnects,
+		config.CgrConfig().GeneralCfg().ConnectTimeout, config.CgrConfig().GeneralCfg().ReplyTimeout,
+		rpcclient.InternalRPC, connChan, true, nil)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	s := RPCClientSet{
+		"APIerSv1": client,
+	}
+	method := "APIerSv1.Ping"
+	var args int
+	var reply *int
+
+	experr := fmt.Sprintf("nil rpc in argument method: %s in: %v out: %v",
+		method, args, reply)
+	err = s.Call(method, args, reply)
+
+	if err == nil || err.Error() != experr {
+		t.Errorf("\nexpected: <%+v>, \nreceived: <%+v>", experr, err)
+	}
+}