diff --git a/utils/coreutils.go b/utils/coreutils.go
index 6f68a4538..c05d73dda 100644
--- a/utils/coreutils.go
+++ b/utils/coreutils.go
@@ -216,12 +216,7 @@ func ParseTimeDetectLayout(tmStr string, timezone string) (time.Time, error) {
 	case tmStr == "*monthly":
 		return time.Now().AddDate(0, 1, 0), nil // add one month
 	case tmStr == "*monthly_estimated":
-		initialMnt := time.Now().Month()
-		tAfter := time.Now().AddDate(0, 1, 0)
-		for tAfter.Month()-initialMnt > 1 {
-			tAfter = tAfter.AddDate(0, 0, -1)
-		}
-		return tAfter, nil
+		return monthlyEstimated(time.Now())
 	case tmStr == "*yearly":
 		return time.Now().AddDate(1, 0, 0), nil // add one year
 
@@ -296,6 +291,15 @@ func ParseTimeDetectLayout(tmStr string, timezone string) (time.Time, error) {
 	return nilTime, errors.New("Unsupported time format")
 }
 
+func monthlyEstimated(t1 time.Time) (time.Time, error) {
+	initialMnt := t1.Month()
+	tAfter := t1.AddDate(0, 1, 0)
+	for tAfter.Month()-initialMnt > 1 {
+		tAfter = tAfter.AddDate(0, 0, -1)
+	}
+	return tAfter, nil
+}
+
 // RoundDuration returns a number equal or larger than the amount that exactly
 // is divisible to whole
 func RoundDuration(whole, amount time.Duration) time.Duration {
@@ -403,41 +407,56 @@ func InfieldSplit(val string) []string {
 	return strings.Split(val, INFIELD_SEP)
 }
 
+//Splited Unzip in small functions to have better coverage
 func Unzip(src, dest string) error {
 	r, err := zip.OpenReader(src)
 	if err != nil {
 		return err
 	}
 	defer r.Close()
-
 	for _, f := range r.File {
-		rc, err := f.Open()
-		if err != nil {
-			return err
-		}
-		defer rc.Close()
-
 		path := filepath.Join(dest, f.Name)
 		if f.FileInfo().IsDir() {
 			os.MkdirAll(path, f.Mode())
-		} else {
-			f, err := os.OpenFile(
-				path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, f.Mode())
-			if err != nil {
-				return err
-			}
-			defer f.Close()
-
-			_, err = io.Copy(f, rc)
-			if err != nil {
-				return err
-			}
+			continue
+		}
+		err = unzipFile(f, path, f.Mode())
+		if err != nil {
+			return err
 		}
 	}
+	return err
+}
 
+type zipFile interface {
+	Open() (io.ReadCloser, error)
+}
+
+func unzipFile(f zipFile, path string, fm os.FileMode) (err error) {
+	rc, err := f.Open()
+	if err != nil {
+		return err
+	}
+	err = copyFile(rc, path, fm)
+	rc.Close()
+	if err != nil {
+		return err
+	}
 	return nil
 }
 
+func copyFile(rc io.ReadCloser, path string, fm os.FileMode) (err error) {
+	f, err := os.OpenFile(
+		path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, fm)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	_, err = io.Copy(f, rc)
+	return
+}
+
 // successive Fibonacci numbers.
 func Fib() func() int {
 	a, b := 0, 1
@@ -957,12 +976,10 @@ func AESDecrypt(encrypted string, encKey string) (txt string, err error) {
 // Hash generates the hash text
 func ComputeHash(dataKeys ...string) (lns string, err error) {
 	var hashByts []byte
-	if hashByts, err = bcrypt.GenerateFromPassword(
+	hashByts, err = bcrypt.GenerateFromPassword(
 		[]byte(ConcatenatedKey(dataKeys...)),
-		bcrypt.MinCost); err != nil {
-		return
-	}
-	return string(hashByts), nil
+		bcrypt.MinCost)
+	return string(hashByts), err
 }
 
 // VerifyHash matches the data hash with the dataKeys ha
diff --git a/utils/coreutils_it_test.go b/utils/coreutils_it_test.go
new file mode 100644
index 000000000..643fdcef7
--- /dev/null
+++ b/utils/coreutils_it_test.go
@@ -0,0 +1,140 @@
+/*
+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 utils
+
+import (
+	"archive/zip"
+	"fmt"
+	"io"
+	"os"
+	"path"
+	"testing"
+)
+
+var (
+	tests = []func(t *testing.T){
+		testLongExecTimeDetector,
+		testUnzip,
+		testUnzipADirectory,
+		testUnzipOpenFileError,
+	}
+)
+
+func TestCoreUtilsIT(t *testing.T) {
+	for _, tests := range tests {
+		t.Run("Core_utils", tests)
+	}
+}
+
+func testLongExecTimeDetector(t *testing.T) {
+	if rcv := LongExecTimeDetector("RandomMessage", -1); cap(rcv) != 1 {
+		t.Errorf("Expected %+v, received %+v", 1, cap(rcv))
+	}
+}
+
+func testUnzip(t *testing.T) {
+	flPath := "/tmp/testUnzip"
+	if err := os.MkdirAll(flPath, 0777); err != nil {
+		t.Error(err)
+	}
+	newFile, err := os.Create(path.Join(flPath, "random.zip"))
+	if err != nil {
+		t.Error(err)
+	}
+
+	expectedErr := "zip: not a valid zip file"
+	if err := Unzip(path.Join(flPath, "random.zip"), EmptyString); err == nil || err.Error() != expectedErr {
+		t.Errorf("Expected %+v, received %+v", expectedErr, err)
+	}
+
+	w := zip.NewWriter(newFile)
+	for _, file := range []string{"file.txt"} {
+		f, err := w.Create(file)
+		if err != nil {
+			t.Error(err)
+		}
+		f.Write([]byte("noMessage"))
+	}
+
+	w.Close()
+
+	newFile.Close()
+
+	expectedErr = "open /tmp/randomMessage/file.txt: no such file or directory"
+	if err := Unzip(path.Join(flPath, "random.zip"), "/tmp/randomMessage"); err == nil || err.Error() != expectedErr {
+		t.Errorf("Expected %+v, received %+v", expectedErr, err)
+	}
+
+	if err = os.Remove(path.Join(flPath, "random.zip")); err != nil {
+		t.Fatal(err)
+	}
+
+	if err = os.RemoveAll(flPath); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func testUnzipADirectory(t *testing.T) {
+	flPath := "/tmp/testUnzip"
+	if err := os.MkdirAll(flPath, 0777); err != nil {
+		t.Error(err)
+	}
+	newFile, err := os.Create(path.Join(flPath, "random.zip"))
+	if err != nil {
+		t.Error(err)
+	}
+
+	w := zip.NewWriter(newFile)
+
+	for _, file := range []string{"file/", "file.txt"} {
+		f, err := w.Create(file)
+		if err != nil {
+			t.Error(err)
+		}
+		f.Write([]byte(`noMessage`))
+	}
+
+	w.Close()
+
+	newFile.Close()
+
+	if err := Unzip(path.Join(flPath, "random.zip"), flPath); err != nil {
+		t.Error(err)
+	}
+	if err = os.Remove(path.Join(flPath, "random.zip")); err != nil {
+		t.Fatal(err)
+	}
+
+	if err = os.RemoveAll(flPath); err != nil {
+		t.Fatal(err)
+	}
+}
+
+type zipFileTest struct{}
+
+func (zipFileTest) Open() (io.ReadCloser, error) {
+	return nil, fmt.Errorf("Cannot open the file")
+}
+
+func testUnzipOpenFileError(t *testing.T) {
+	expectdErr := "Cannot open the file"
+	if err := unzipFile(new(zipFileTest), EmptyString, 0); err == nil || err.Error() != expectdErr {
+		t.Errorf("Expected %+v, received %+v", expectdErr, err)
+	}
+}
diff --git a/utils/coreutils_test.go b/utils/coreutils_test.go
index 8bd1d91fc..04aa5e1c3 100644
--- a/utils/coreutils_test.go
+++ b/utils/coreutils_test.go
@@ -1600,3 +1600,13 @@ func TestBoolGenerator(t *testing.T) {
 		t.Errorf("Needs to be bool")
 	}
 }
+
+func TestMonthlyEstimated(t *testing.T) {
+	t1 := time.Date(2021, 1, 31, 0, 0, 0, 0, time.UTC)
+	expectedTime := time.Date(2021, 2, 28, 0, 0, 0, 0, time.UTC)
+	if rcv, err := monthlyEstimated(t1); err != nil {
+		t.Error(err)
+	} else if !reflect.DeepEqual(rcv, expectedTime) {
+		t.Errorf("Expected %+v, received %+v", expectedTime, rcv)
+	}
+}
diff --git a/utils/stir_shaken_utils_it_test.go b/utils/stir_shaken_utils_it_test.go
index 68130a647..bf3277ba6 100644
--- a/utils/stir_shaken_utils_it_test.go
+++ b/utils/stir_shaken_utils_it_test.go
@@ -19,8 +19,11 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>
 package utils
 
 import (
+	"reflect"
 	"testing"
 	"time"
+
+	"github.com/dgrijalva/jwt-go"
 )
 
 var (
@@ -55,17 +58,36 @@ func testGetReaderFromPathStatusCode(t *testing.T) {
 }
 
 func testNewECDSAPrvKey(t *testing.T) {
-	urlPath := "https://en.wikipedia.org/wiki/Elliptic_Curve_Digital_Signature_Algorithm"
-	expPrvKey := "Invalid Key: Key must be PEM encoded PKCS1 or PKCS8 private key"
-	if _, err := NewECDSAPrvKey(urlPath, time.Duration(0)); err == nil || err.Error() != expPrvKey {
-		t.Errorf("Expected %+v, received %+v", expPrvKey, err)
+	urlPath := "https://raw.githubusercontent.com/cgrates/cgrates/master/data/stir/stir_privatekey.pem"
+	expected, err := jwt.ParseECPrivateKeyFromPEM([]byte(`
+-----BEGIN EC PRIVATE KEY-----
+MHcCAQEEICcL1+2nj9ylMlTKjSpIGx03gALK0cISciviwudQuvb9oAoGCCqGSM49
+AwEHoUQDQgAEjS4zmWotYqKWB2/sn+4v1uUoPAQ2N2ZtrUsmewkl3ErAbIokXSZS
+rucJPPszlBtYbbhcmbXC7DKP9u9Pq/GnVg==
+-----END EC PRIVATE KEY-----`))
+	if err != nil {
+		t.Error(err)
+	}
+	if prvKey, err := NewECDSAPrvKey(urlPath, time.Duration(0)); err != nil {
+		t.Error(err)
+	} else if !reflect.DeepEqual(expected, prvKey) {
+		t.Errorf("Expected %+v, received %+v", expected, prvKey)
 	}
 }
 
 func testNewECDSAPublicKey(t *testing.T) {
-	urlPath := "https://en.wikipedia.org/wiki/Wiki"
-	expPublKey := "Invalid Key: Key must be PEM encoded PKCS1 or PKCS8 private key"
-	if _, err := NewECDSAPubKey(urlPath, 0); err == nil || err.Error() != expPublKey {
-		t.Errorf("Expected %+v, received %+v", expPublKey, err)
+	urlPath := "https://raw.githubusercontent.com/cgrates/cgrates/master/data/stir/stir_pubkey.pem"
+	expPublKey, err := jwt.ParseECPublicKeyFromPEM([]byte(` 
+-----BEGIN PUBLIC KEY-----
+MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEjS4zmWotYqKWB2/sn+4v1uUoPAQ2
+N2ZtrUsmewkl3ErAbIokXSZSrucJPPszlBtYbbhcmbXC7DKP9u9Pq/GnVg==
+-----END PUBLIC KEY-----`))
+	if err != nil {
+		t.Error(err)
+	}
+	if publKey, err := NewECDSAPubKey(urlPath, 0); err != nil {
+		t.Error(err)
+	} else if !reflect.DeepEqual(expPublKey, publKey) {
+		t.Errorf("Expected %+v, received %+v", expPublKey, publKey)
 	}
 }