diff --git a/utils/coreutils_test.go b/utils/coreutils_test.go
index 16eb20be7..17e1ddf68 100644
--- a/utils/coreutils_test.go
+++ b/utils/coreutils_test.go
@@ -748,28 +748,35 @@ func TestParseZeroRatingSubject(t *testing.T) {
 		MetaVoice: "*zero1s",
 	}
 	for i, s := range subj {
-		if d, err := ParseZeroRatingSubject(MetaVoice, s, dfltRatingSubject, true); err != nil || d != dur[i] {
-			t.Error("Error parsing rating subject: ", s, d, err)
+		if i == 0 {
+			if d, err := ParseZeroRatingSubject(MetaVoice, s, dfltRatingSubject, false); err == nil {
+				t.Error("Error parsing rating subject: ", s, d, err)
+			}
+
+		} else {
+			if d, err := ParseZeroRatingSubject(MetaVoice, s, dfltRatingSubject, true); err != nil || d != dur[i] {
+				t.Error("Error parsing rating subject: ", s, d, err)
+			}
+
+		}
+		if d, err := ParseZeroRatingSubject(MetaData, EmptyString, dfltRatingSubject, true); err != nil || d != time.Nanosecond {
+			t.Error("Error parsing rating subject: ", EmptyString, d, err)
+		}
+		if d, err := ParseZeroRatingSubject(MetaSMS, EmptyString, dfltRatingSubject, true); err != nil || d != time.Nanosecond {
+			t.Error("Error parsing rating subject: ", EmptyString, d, err)
+		}
+		if d, err := ParseZeroRatingSubject(MetaMMS, EmptyString, dfltRatingSubject, true); err != nil || d != time.Nanosecond {
+			t.Error("Error parsing rating subject: ", EmptyString, d, err)
+		}
+		if d, err := ParseZeroRatingSubject(MetaMonetary, EmptyString, dfltRatingSubject, true); err != nil || d != time.Nanosecond {
+			t.Error("Error parsing rating subject: ", EmptyString, d, err)
+		}
+		expecting := "malformed rating subject: test"
+		if _, err := ParseZeroRatingSubject(MetaMonetary, "test", dfltRatingSubject, true); err == nil || err.Error() != expecting {
+			t.Errorf("Expecting: %+v, received: %+v ", expecting, err)
 		}
 	}
-	if d, err := ParseZeroRatingSubject(MetaData, EmptyString, dfltRatingSubject, true); err != nil || d != time.Nanosecond {
-		t.Error("Error parsing rating subject: ", EmptyString, d, err)
-	}
-	if d, err := ParseZeroRatingSubject(MetaSMS, EmptyString, dfltRatingSubject, true); err != nil || d != time.Nanosecond {
-		t.Error("Error parsing rating subject: ", EmptyString, d, err)
-	}
-	if d, err := ParseZeroRatingSubject(MetaMMS, EmptyString, dfltRatingSubject, true); err != nil || d != time.Nanosecond {
-		t.Error("Error parsing rating subject: ", EmptyString, d, err)
-	}
-	if d, err := ParseZeroRatingSubject(MetaMonetary, EmptyString, dfltRatingSubject, true); err != nil || d != time.Nanosecond {
-		t.Error("Error parsing rating subject: ", EmptyString, d, err)
-	}
-	expecting := "malformed rating subject: test"
-	if _, err := ParseZeroRatingSubject(MetaMonetary, "test", dfltRatingSubject, true); err == nil || err.Error() != expecting {
-		t.Errorf("Expecting: %+v, received: %+v ", expecting, err)
-	}
 }
-
 func TestConcatenatedKey(t *testing.T) {
 	if key := ConcatenatedKey("a"); key != "a" {
 		t.Error("Unexpected key value received: ", key)
@@ -1185,6 +1192,16 @@ func TestDurationPointer(t *testing.T) {
 	}
 }
 
+func TestSliceStringPointer(t *testing.T) {
+	sl := []string{"test"}
+	result := SliceStringPointer(sl)
+	exp := result
+	if !reflect.DeepEqual(result, exp) {
+		t.Errorf("Expeced:%+q but received %+q", exp, result)
+	}
+
+}
+
 func TestToIJSON(t *testing.T) {
 	str := "string"
 	received := ToIJSON(str)
@@ -1884,4 +1901,8 @@ func TestCoreUtilsFibDurationSeqNrOverflow(t *testing.T) {
 			t.Errorf("expected: <%+v>, \nreceived: <%+v>", AbsoluteMaxDuration, rcv)
 		}
 	}
+	fib = FibDuration(time.Second, 6)
+	if rcv := fib(); rcv != 6 {
+		t.Errorf("expected: <%+v>, \nreceived: <%+v>", AbsoluteMaxDuration, rcv)
+	}
 }
diff --git a/utils/dataconverter_test.go b/utils/dataconverter_test.go
index 413e61def..be71e45b8 100644
--- a/utils/dataconverter_test.go
+++ b/utils/dataconverter_test.go
@@ -1132,6 +1132,9 @@ func TestLenTimeConverter3(t *testing.T) {
 	} else if !reflect.DeepEqual(expected, rcv) {
 		t.Errorf("Expecting: %+v, received: %+v", expected, rcv)
 	}
+	if rcv, err := cnv.Convert(nil); err != nil {
+		t.Errorf("Expecting: %+v, received: %+v", expected, rcv)
+	}
 }
 
 func TestFloat64Converter(t *testing.T) {
@@ -1180,6 +1183,10 @@ func TestSliceConverter(t *testing.T) {
 	} else if !reflect.DeepEqual(expected2, rcv) {
 		t.Errorf("Expecting: %+v, received: %+v", expected, rcv)
 	}
+
+	if _, err := cnv.Convert(`test`); err != nil {
+		t.Error(err)
+	}
 }
 
 func TestE164FromNAPTRConverter(t *testing.T) {
@@ -1191,6 +1198,9 @@ func TestE164FromNAPTRConverter(t *testing.T) {
 	if !reflect.DeepEqual(exp, cnv) {
 		t.Errorf("Expecting: %+v, received: %+v", exp, cnv)
 	}
+	if _, err := cnv.Convert("8.7.6.5.4.3.2.1"); err == nil {
+		t.Error("Error")
+	}
 	if e164, err := cnv.Convert("8.7.6.5.4.3.2.1.0.1.6.e164.arpa."); err != nil {
 		t.Error(err)
 	} else if e164 != "61012345678" {
@@ -1207,6 +1217,7 @@ func TestDomainNameFromNAPTRConverter(t *testing.T) {
 	if !reflect.DeepEqual(exp, cnv) {
 		t.Errorf("Expecting: %+v, received: %+v", exp, cnv)
 	}
+
 	if dName, err := cnv.Convert("8.7.6.5.4.3.2.1.0.1.6.e164.arpa."); err != nil {
 		t.Fatal(err)
 	} else if dName != "e164.arpa" {
diff --git a/utils/safemapstorage_test.go b/utils/safemapstorage_test.go
index 9037d9dee..4aeb7e9b8 100644
--- a/utils/safemapstorage_test.go
+++ b/utils/safemapstorage_test.go
@@ -144,3 +144,17 @@ func TestSafeMapStorageClone(t *testing.T) {
 		t.Errorf("Expected %v \n but received \n %v", expected, reply)
 	}
 }
+
+func TestSafeMapClonedMapStorage(t *testing.T) {
+
+	ms := &SafeMapStorage{
+		MapStorage: MapStorage{
+			"field1": 2,
+			"field2": 3,
+		},
+	}
+
+	if reply := ms.ClonedMapStorage(); reflect.DeepEqual(ms, reply) {
+		t.Errorf("Expected %v \n but received \n %v", ms, reply)
+	}
+}
diff --git a/utils/stringset_test.go b/utils/stringset_test.go
index 47616a616..99d24ffb6 100644
--- a/utils/stringset_test.go
+++ b/utils/stringset_test.go
@@ -19,6 +19,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>
 package utils
 
 import (
+	"encoding/json"
 	"reflect"
 	"sort"
 	"testing"
@@ -298,3 +299,23 @@ func TestStringFieldAsString(t *testing.T) {
 		t.Errorf("expected %v got error", exp)
 	}
 }
+
+func TestStringString(t *testing.T) {
+	s := StringSet{
+		"key1": struct{}{},
+		"key2": struct{}{},
+		"key3": struct{}{},
+	}
+	exp := `["key1","key2","key3"]`
+
+	rcv := s.String()
+	rcvAsMap := []string{}
+	if err := json.Unmarshal([]byte(rcv), &rcvAsMap); err != nil {
+		t.Error(err)
+	}
+	rcv = ToJSON(rcvAsMap)
+	if rcv != exp {
+		t.Errorf("expected %v received %v", exp, rcv)
+	}
+
+}
diff --git a/utils/value_formula_test.go b/utils/value_formula_test.go
index 598893702..3477a0d73 100644
--- a/utils/value_formula_test.go
+++ b/utils/value_formula_test.go
@@ -299,7 +299,9 @@ func TestValueFieldAsInterface(t *testing.T) {
 	fldPath = []string{"test1"}
 	vf = &ValueFormula{
 		Method: "Method",
-		Params: map[string]interface{}{},
+		Params: map[string]interface{}{
+			"key": "val",
+		},
 		Static: 22,
 	}
 	if val, _ := vf.FieldAsInterface(fldPath); val != nil {
@@ -330,4 +332,32 @@ func TestValueFieldAsInterface(t *testing.T) {
 		t.Error("expected error")
 	}
 
+	fldPath = []string{"Params[key]"}
+	if _, err := vf.FieldAsInterface(fldPath); err != nil {
+
+		t.Errorf("expected error nil but received %v", err)
+	}
+
+}
+
+func TestValueFieldAsString(t *testing.T) {
+	vf := &ValueFormula{}
+	fldPath := []string{}
+
+	if _, err := vf.FieldAsString(fldPath); err == nil {
+		t.Error("expected error")
+	}
+
+	vf = &ValueFormula{
+		Method: "Method",
+		Params: map[string]interface{}{
+			"Params": "index",
+		},
+		Static: 22,
+	}
+	fldPath = []string{"Params"}
+	if val, err := vf.FieldAsString(fldPath); err != nil {
+		t.Errorf("expected %v", val)
+	}
+
 }