diff --git a/engine/cdrs_test.go b/engine/cdrs_test.go
new file mode 100644
index 000000000..b29d5c4b9
--- /dev/null
+++ b/engine/cdrs_test.go
@@ -0,0 +1,126 @@
+/*
+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 (
+	"reflect"
+	"testing"
+	"time"
+
+	"github.com/cgrates/birpc/context"
+	"github.com/cgrates/cgrates/config"
+	"github.com/cgrates/cgrates/guardian"
+	"github.com/cgrates/cgrates/utils"
+)
+
+func TestCDRsNewCDRServer(t *testing.T) {
+	var sent StorDB
+	cfg := config.NewDefaultCGRConfig()
+	storDBChan := make(chan StorDB, 1)
+	storDBChan <- sent
+	dm := &DataManager{}
+	fltrs := &FilterS{}
+	connMng := &ConnManager{}
+	newCDRSrv := NewCDRServer(cfg, storDBChan, dm, fltrs, connMng)
+	expected := &CDRServer{
+		cfg:        cfg,
+		cdrDB:      sent,
+		dm:         dm,
+		guard:      guardian.Guardian,
+		filterS:    fltrs,
+		connMgr:    connMng,
+		storDBChan: storDBChan,
+	}
+	if !reflect.DeepEqual(newCDRSrv, expected) {
+		t.Errorf("\nExpected <%+v> \n, received <%+v>", expected, newCDRSrv)
+	}
+}
+
+func TestCDRsListenAndServeCaseStorDBChanOK(t *testing.T) {
+	var sent StorDB
+	cfg := config.NewDefaultCGRConfig()
+	storDBChan := make(chan StorDB, 1)
+	storDBChan <- sent
+	dm := &DataManager{}
+	fltrs := &FilterS{}
+	connMng := &ConnManager{}
+	newCDRSrv := NewCDRServer(cfg, storDBChan, dm, fltrs, connMng)
+	stopChan := make(chan struct{}, 1)
+	func() {
+		storDBChan <- sent
+		time.Sleep(10 * time.Millisecond)
+		stopChan <- struct{}{}
+	}()
+	newCDRSrv.ListenAndServe(stopChan)
+	if !reflect.DeepEqual(newCDRSrv.cdrDB, sent) {
+		t.Errorf("\nExpected <%+v> \n, received <%+v>", sent, newCDRSrv.cdrDB)
+	}
+}
+
+func TestCDRsListenAndServeCaseStorDBChanNotOK(t *testing.T) {
+	var sent StorDB
+	cfg := config.NewDefaultCGRConfig()
+	storDBChan := make(chan StorDB, 1)
+	storDBChan <- sent
+	dm := &DataManager{}
+	fltrs := &FilterS{}
+	connMng := &ConnManager{}
+	newCDRSrv := NewCDRServer(cfg, storDBChan, dm, fltrs, connMng)
+	stopChan := make(chan struct{}, 1)
+	func() {
+		time.Sleep(30 * time.Millisecond)
+		close(storDBChan)
+	}()
+	newCDRSrv.ListenAndServe(stopChan)
+	if !reflect.DeepEqual(newCDRSrv.cdrDB, nil) {
+		t.Errorf("\nExpected <%+v> \n, received <%+v>", nil, newCDRSrv.cdrDB)
+	}
+}
+
+func TestCDRsChrgrSProcessEventErrMsnConnIDs(t *testing.T) {
+	var sent StorDB
+	cfg := config.NewDefaultCGRConfig()
+	storDBChan := make(chan StorDB, 1)
+	storDBChan <- sent
+	dm := &DataManager{}
+	fltrs := &FilterS{}
+	connMng := &ConnManager{}
+	newCDRSrv := NewCDRServer(cfg, storDBChan, dm, fltrs, connMng)
+
+	cgrEv := &utils.CGREvent{
+		Tenant: "cgrates.org",
+		ID:     "testID",
+		Event: map[string]interface{}{
+			"Resources":      "ResourceProfile1",
+			utils.AnswerTime: time.Date(2014, 7, 14, 14, 30, 0, 0, time.UTC),
+			"UsageInterval":  "1s",
+			"PddInterval":    "1s",
+			utils.Weight:     "20.0",
+			utils.Usage:      135 * time.Second,
+			utils.Cost:       123.0,
+		},
+		APIOpts: map[string]interface{}{
+			utils.Subsys: utils.MetaChargers,
+		},
+	}
+	_, err := newCDRSrv.chrgrSProcessEvent(context.Background(), cgrEv)
+	if err == nil || err.Error() != "MANDATORY_IE_MISSING: [connIDs]" {
+		t.Errorf("\nExpected <%+v> \n, received <%+v>", nil, err)
+	}
+
+}