diff --git a/engine/z_resources_test.go b/engine/z_resources_test.go
index 6f99af9d1..c147a3320 100644
--- a/engine/z_resources_test.go
+++ b/engine/z_resources_test.go
@@ -18,7 +18,12 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>
 package engine
 
 import (
+	"bytes"
+	"fmt"
+	"log"
+	"os"
 	"reflect"
+	"strings"
 	"testing"
 	"time"
 
@@ -2820,6 +2825,265 @@ func TestResourceCaching(t *testing.T) {
 	}
 }
 
+func TestResourcesRemoveExpiredUnitsResetTotalUsage(t *testing.T) {
+	utils.Logger.SetLogLevel(4)
+	utils.Logger.SetSyslog(nil)
+
+	var buf bytes.Buffer
+	log.SetOutput(&buf)
+	defer func() {
+		log.SetOutput(os.Stderr)
+	}()
+
+	r := &Resource{
+		TTLIdx: []string{"ResGroup1", "ResGroup2", "ResGroup3"},
+		Usages: map[string]*ResourceUsage{
+			"ResGroup2": {
+				Tenant:     "cgrates.org",
+				ID:         "RU_2",
+				Units:      11,
+				ExpiryTime: time.Date(2021, 5, 3, 13, 0, 0, 0, time.UTC),
+			},
+			"ResGroup3": {
+				Tenant: "cgrates.org",
+				ID:     "RU_3",
+			},
+		},
+		tUsage: utils.Float64Pointer(10),
+	}
+
+	exp := &Resource{
+		TTLIdx: []string{"ResGroup3"},
+		Usages: map[string]*ResourceUsage{
+			"ResGroup3": {
+				Tenant: "cgrates.org",
+				ID:     "RU_3",
+			},
+		},
+	}
+
+	explog := "CGRateS <> [WARNING] resetting total usage for resourceID: , usage smaller than 0: -1.000000\n"
+	r.removeExpiredUnits()
+
+	if !reflect.DeepEqual(r, exp) {
+		t.Errorf("\nexpected: <%+v>, \nreceived: <%+v>", exp, r)
+	}
+
+	rcvlog := buf.String()[20:]
+	if rcvlog != explog {
+		t.Errorf("\nexpected: <%+v>, \nreceived: <%+v>", explog, rcvlog)
+	}
+
+	utils.Logger.SetLogLevel(0)
+}
+
+func TestResourcesAvailable(t *testing.T) {
+	r := ResourceWithConfig{
+		Resource: &Resource{
+			Usages: map[string]*ResourceUsage{
+				"RU_1": {
+					Units: 4,
+				},
+				"RU_2": {
+					Units: 7,
+				},
+			},
+		},
+		Config: &ResourceProfile{
+			Limit: 10,
+		},
+	}
+
+	exp := -1.0
+	rcv := r.Available()
+
+	if rcv != exp {
+		t.Errorf("\nexpected: <%+v>, \nreceived: <%+v>", exp, rcv)
+	}
+}
+
+func TestResourcesRecordUsageZeroTTL(t *testing.T) {
+	r := &Resource{
+		Usages: map[string]*ResourceUsage{
+			"RU_1": {
+				Tenant: "cgrates.org",
+				ID:     "RU_1",
+			},
+		},
+		ttl: utils.DurationPointer(0),
+	}
+	ru := &ResourceUsage{
+		ID: "RU_2",
+	}
+
+	err := r.recordUsage(ru)
+
+	if err != nil {
+		t.Errorf("\nexpected: <%+v>, \nreceived: <%+v>", nil, err)
+	}
+}
+
+func TestResourcesRecordUsageGtZeroTTL(t *testing.T) {
+	r := &Resource{
+		Usages: map[string]*ResourceUsage{
+			"RU_1": {
+				Tenant: "cgrates.org",
+				ID:     "RU_1",
+			},
+		},
+		TTLIdx: []string{"RU_1"},
+		ttl:    utils.DurationPointer(1 * time.Second),
+	}
+	ru := &ResourceUsage{
+		Tenant: "cgrates.org",
+		ID:     "RU_2",
+	}
+
+	exp := &Resource{
+		Usages: map[string]*ResourceUsage{
+			"RU_1": {
+				Tenant: "cgrates.org",
+				ID:     "RU_1",
+			},
+			"RU_2": {
+				Tenant: "cgrates.org",
+				ID:     "RU_2",
+			},
+		},
+		TTLIdx: []string{"RU_1", "RU_2"},
+		ttl:    utils.DurationPointer(1 * time.Second),
+	}
+	err := r.recordUsage(ru)
+	exp.Usages[ru.ID].ExpiryTime = r.Usages[ru.ID].ExpiryTime
+
+	if err != nil {
+		t.Errorf("\nexpected: <%+v>, \nreceived: <%+v>", nil, err)
+	}
+
+	if !reflect.DeepEqual(r, exp) {
+		t.Errorf("\nexpected: <%+v>, \nreceived: <%+v>", utils.ToJSON(exp), utils.ToJSON(r))
+	}
+}
+
+type mockWriter struct {
+	WriteF func(p []byte) (n int, err error)
+}
+
+func (mW *mockWriter) Write(p []byte) (n int, err error) {
+	if mW.WriteF != nil {
+		return mW.WriteF(p)
+	}
+	return 0, nil
+}
+
+func TestResourcesRecordUsageClearErr(t *testing.T) {
+	utils.Logger.SetLogLevel(4)
+	utils.Logger.SetSyslog(nil)
+
+	var buf bytes.Buffer
+
+	rs := Resources{
+		{
+			Usages: map[string]*ResourceUsage{
+				"RU_1": {
+					Tenant: "cgrates.org",
+					ID:     "RU_1",
+				},
+				"RU_2": {
+					Tenant: "cgrates.org",
+					ID:     "RU_2",
+				},
+			},
+			TTLIdx: []string{"RU_1", "RU_2"},
+			ttl:    utils.DurationPointer(1 * time.Second),
+		},
+		{
+			Usages: map[string]*ResourceUsage{
+				"RU_3": {
+					Tenant: "cgrates.org",
+					ID:     "RU_3",
+				},
+				"RU_4": {
+					Tenant: "cgrates.org",
+					ID:     "RU_4",
+				},
+			},
+			TTLIdx: []string{"RU_3"},
+			ttl:    utils.DurationPointer(2 * time.Second),
+		},
+	}
+
+	ru := &ResourceUsage{
+		Tenant: "cgrates.org",
+		ID:     "RU_4",
+	}
+
+	exp := Resources{
+		{
+			Usages: map[string]*ResourceUsage{
+				"RU_1": {
+					Tenant: "cgrates.org",
+					ID:     "RU_1",
+				},
+				"RU_2": {
+					Tenant: "cgrates.org",
+					ID:     "RU_2",
+				},
+			},
+			TTLIdx: []string{"RU_1", "RU_2", "RU_4"},
+			ttl:    utils.DurationPointer(1 * time.Second),
+		},
+		{
+			Usages: map[string]*ResourceUsage{
+				"RU_3": {
+					Tenant: "cgrates.org",
+					ID:     "RU_3",
+				},
+				"RU_4": {
+					Tenant: "cgrates.org",
+					ID:     "RU_4",
+				},
+			},
+			TTLIdx: []string{"RU_3"},
+			ttl:    utils.DurationPointer(2 * time.Second),
+		},
+	}
+
+	explog := []string{
+		fmt.Sprintf("CGRateS <> [WARNING] <%s>cannot record usage, err: duplicate resource usage with id: %s:%s", utils.ResourceS, ru.Tenant, ru.ID),
+		fmt.Sprintf("CGRateS <> [WARNING] <%s> cannot clear usage, err: cannot find usage record with id: %s", utils.ResourceS, ru.ID),
+	}
+	experr := fmt.Sprintf("duplicate resource usage with id: %s", "cgrates.org:"+ru.ID)
+
+	defer log.SetOutput(os.Stderr)
+	log.SetOutput(&mockWriter{
+		WriteF: func(p []byte) (n int, err error) {
+			delete(rs[0].Usages, "RU_4")
+			return buf.Write(p)
+		},
+	})
+
+	err := rs.recordUsage(ru)
+
+	if err == nil || err.Error() != experr {
+		t.Errorf("\nexpected: <%+v>, \nreceived: <%+v>", experr, err)
+	}
+
+	if !reflect.DeepEqual(rs, exp) {
+		t.Errorf("\nexpected: <%+v>, \nreceived: <%+v>", utils.ToJSON(exp), utils.ToJSON(rs))
+	}
+
+	rcv := strings.Split(buf.String(), "\n")
+	for idx, exp := range explog {
+		rcv[idx] = rcv[idx][20:]
+		if rcv[idx] != exp {
+			t.Errorf("\nexpected: <%+v>, \nreceived: <%+v>", exp, rcv[idx])
+		}
+	}
+
+	utils.Logger.SetLogLevel(0)
+}
+
 func TestResourceAllocateResourceOtherDB(t *testing.T) {
 	rProf := &ResourceProfile{
 		Tenant:       "cgrates.org",