diff --git a/index.js b/index.js
index 7954fdb..6319c78 100644
--- a/index.js
+++ b/index.js
@@ -53,7 +53,7 @@ module.exports = {
   departments: (regionName) => {
     regionName = lowerCase(regionName);
 
-    if (regionName.length == 0) {
+    if (regionName?.length == 0) {
       throw new RegionReferenceError();
     }
 
@@ -73,7 +73,7 @@ module.exports = {
   population: (regionName) => {
     regionName = lowerCase(regionName);
 
-    if (regionName.length == 0) {
+    if (regionName?.length == 0) {
       throw new RegionReferenceError();
     }
 
@@ -93,7 +93,7 @@ module.exports = {
   superficie: (regionName) => {
     regionName = lowerCase(regionName);
 
-    if (regionName.length == 0) {
+    if (regionName?.length == 0) {
       throw new RegionReferenceError();
     }
 
@@ -125,7 +125,7 @@ module.exports = {
   arrondissements: (departmentName) => {
     departmentName = lowerCase(departmentName);
 
-    if (departmentName.length == 0) {
+    if (departmentName?.length == 0) {
       throw new DepartmentReferenceError();
     }
 
@@ -145,7 +145,7 @@ module.exports = {
   populationDepartment: (departmentName) => {
     departmentName = lowerCase(departmentName);
 
-    if (departmentName.length == 0) {
+    if (departmentName?.length == 0) {
       throw new DepartmentReferenceError();
     }
 
@@ -165,7 +165,7 @@ module.exports = {
   superficieDepartment: (departmentName) => {
     departmentName = lowerCase(departmentName);
 
-    if (departmentName.length == 0) {
+    if (departmentName?.length == 0) {
       throw new DepartmentReferenceError();
     }
 
diff --git a/libs/utils.js b/libs/utils.js
index 56e2c93..f92ccec 100644
--- a/libs/utils.js
+++ b/libs/utils.js
@@ -1,8 +1,8 @@
 const rg = require("../dataset/regions.json");
 const dp = require("../dataset/departments.json");
-// const { DepartmentReferenceError } = require("./exceptions");
+const { DepartmentReferenceError, RegionReferenceError} = require("./exceptions");
 
-const lowerCase = (value) => value.toLowerCase().trim();
+const lowerCase = (value) => value?.toLowerCase().trim();
 
 const findItem = (value) => {
 	const region = rg.find(
diff --git a/mock/galsenify.test.mock.js b/mock/galsenify.test.mock.js
new file mode 100644
index 0000000..34e7341
--- /dev/null
+++ b/mock/galsenify.test.mock.js
@@ -0,0 +1,111 @@
+const regionNamesMock = [
+  "Dakar",
+  "Diourbel",
+  "Fatick",
+  "Kaffrine",
+  "Kaolack",
+  "Kédougou",
+  "Kolda",
+  "Louga",
+  "Matam",
+  "Saint-Louis",
+  "Sédhiou",
+  "Tambacounda",
+  "Thies",
+  "Ziguinchor",
+];
+
+const departmentsMock = [
+  "Dakar",
+  "Pikine",
+  "Guédiawaye",
+  "Rufisque",
+  "Keur Massar",
+];
+
+const codeMock = [
+  "DK",
+  "DB",
+  "FK",
+  "KA",
+  "KL",
+  "KE",
+  "KD",
+  "LG",
+  "MT",
+  "SL",
+  "SE",
+  "TC",
+  "TH",
+  "ZG",
+];
+
+const languesNationalesMock = [
+  "Wolof",
+  "Pular",
+  "Sérère",
+  "Diola",
+  "Mandingue",
+  "Soninké",
+  "Bambara",
+];
+
+const allDepartmentMock = [
+  "Dakar",
+  "Guédiawaye",
+  "Keur Massar",
+  "Pikine",
+  "Rufisque",
+  "Bambey",
+  "Diourbel",
+  "Mbacké",
+  "Fatick",
+  "Foundiougne",
+  "Gossas",
+  "Birkelane",
+  "Kaffrine",
+  "Koungheul",
+  "Malème-Hodar",
+  "Guinguinéo",
+  "Kaolack",
+  "Nioro du Rip",
+  "Kédougou",
+  "Salemata",
+  "Saraya",
+  "Kolda",
+  "Vélingara",
+  "Médina Yoro Foulah",
+  "Kébémer",
+  "Linguère",
+  "Louga",
+  "Kanel",
+  "Matam",
+  "Ranérou-Ferlo",
+  "Dagana",
+  "Podor",
+  "Saint-Louis",
+  "Bounkiling",
+  "Goudomp",
+  "Sédhiou",
+  "Bakel",
+  "Goudiry",
+  "Koumpentoum",
+  "Tambacounda",
+  "Mbour",
+  "Thies",
+  "Tivaouane",
+  "Bignona",
+  "Oussouye",
+  "Ziguinchor",
+];
+
+const arrondissementsMock = ["Dagoudane", "Thiaroye"];
+
+module.exports = {
+  regionNamesMock,
+  departmentsMock,
+  codeMock,
+  languesNationalesMock,
+  allDepartmentMock,
+  arrondissementsMock,
+};
diff --git a/test/departments.test.js b/test/departments.test.js
index 3e3aac7..3118e51 100644
--- a/test/departments.test.js
+++ b/test/departments.test.js
@@ -1,21 +1,23 @@
-const department = require("../index")
+const department = require("../index");
+const { allDepartmentMock, arrondissementsMock } = require("../mock/galsenify.test.mock");
+
 
 describe("Department testing", () => {
   test("receive the department", () => {
     const departmentName = department.allDepartments();
-    expect(departmentName.length).toEqual(departmentName.length);
-    expect(departmentName).toContain("Dakar");
+    expect(departmentName.length).toEqual(allDepartmentMock.length);
+    expect(departmentName).toEqual(allDepartmentMock);
   });
 
   test("receive the arrondissements of passing department", () => {
     const arrondissements = department.arrondissements("Pikine");
-    expect(arrondissements.length).toBeGreaterThan(0);
-    expect(arrondissements).toContain("Thiaroye");
+    expect(arrondissements.length).toEqual(arrondissementsMock.length);
+    expect(arrondissements).toEqual(arrondissementsMock);
   });
 
   test("receive the arrrondissements of passing department should fail", () => {
-    expect(() => department.arrondissements("Yeumbeul")).toThrow();
-    expect(() => department.arrondissements("")).toThrow();
+    expect(() => department.arrondissements("Yeumbeul")).toThrow("Oups! Ce n'est pas un Département valide !");
+    expect(() => department.arrondissements("")).toThrow("Oups! Ce n'est pas un Département valide !");
   });
 
 });
diff --git a/test/galsenify.test.js b/test/galsenify.test.js
index 7fd0711..5e3c923 100644
--- a/test/galsenify.test.js
+++ b/test/galsenify.test.js
@@ -1,26 +1,28 @@
 const galsenify = require('../index');
+const {regionNamesMock, departmentsMock, codeMock, languesNationalesMock} = require('../mock/galsenify.test.mock');
 
 describe("galsenify testing", () => {
   test("receive the regions", () => {
     const regionNames = galsenify.regions();
-    expect(regionNames.length).toEqual(regionNames.length);
-    expect(regionNames).toContain("Dakar");
+    expect(regionNames.length).toEqual(14);
+    expect(regionNames).toEqual(regionNamesMock);
   });
 
   test("receive the departments of passing region", () => {
     const departments = galsenify.departments("Dakar");
-    expect(departments.length).toBeGreaterThan(0);
-    expect(departments).toContain("Pikine");
+    expect(departments.length).toEqual(departmentsMock.length);
+    expect(departments).toEqual(departmentsMock);
   });
 
   test("receive the departments of passing region should fail", () => {
-    expect(() => galsenify.departments("Adidjan")).toThrow();
-    expect(() => galsenify.departments("")).toThrow();
+    expect(() => galsenify.departments("Adidjan")).toThrow("Oups! Ce n'est pas une région valide !");
+    expect(() => galsenify.departments("")).toThrow("Oups! Ce n'est pas une région valide !");
   });
 
   test("receive the codes", () => {
     const codes = galsenify.codes();
-    expect(codes.length).toBeGreaterThan(0);
+    expect(codes).toEqual(codeMock);
+    expect(codes.length).toEqual(codeMock.length);
   });
 
   test("receive the population of passing region", () => {
@@ -29,8 +31,8 @@ describe("galsenify testing", () => {
   });
 
   test("receive the population of passing region should be fail", () => {
-    expect(() => galsenify.population("Abidjan")).toThrow();
-    expect(() => galsenify.population("")).toThrow();
+    expect(() => galsenify.population("Abidjan")).toThrow("Oups! Ce n'est pas une région valide !");
+    expect(() => galsenify.population("")).toThrow("Oups! Ce n'est pas une région valide !");
   });
 
   test("receive the superficie of passing region", () => {
@@ -39,14 +41,14 @@ describe("galsenify testing", () => {
   });
 
   test("receive the superficie of passing region should be fail", () => {
-    expect(() => galsenify.superficie("Abidjan")).toThrow();
-    expect(() => galsenify.superficie("")).toThrow();
+    expect(() => galsenify.superficie("Abidjan")).toThrow("Oups! Ce n'est pas une région valide !");
+    expect(() => galsenify.superficie("")).toThrow("Oups! Ce n'est pas une région valide !");
   });
 
   test("receive the sn information", () => {
     const sn = galsenify.sn();
     expect(sn.pays).toBe("Sénégal");
     expect(sn.capital).toBe("Dakar");
-    expect(galsenify.languesNationales()).toContain("Wolof");
+    expect(galsenify.languesNationales()).toEqual(languesNationalesMock);
   });
 });