diff --git a/index.js b/index.js
index 1344f31..5e6280d 100644
--- a/index.js
+++ b/index.js
@@ -1,7 +1,12 @@
 const { readFile } = require('./utils/converter')
 
 const add = async (path) => {
-  return  await readFile(`${path}`)
+  try {
+    if (typeof path !== 'string') throw new Error('path have to be an string')
+    return  await readFile(`${path}`)
+  } catch (e) {
+    throw new Error(e.message)
+  }
 }
 
 module.exports = add
diff --git a/package.json b/package.json
index 34409f7..d37f464 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "async-convert-csv-to-json",
-  "version": "1.0.1",
+  "version": "1.1.1",
   "description": "convert csv file to json",
   "main": "index.js",
   "scripts": {
diff --git a/utils/MOCK_DATA.csv b/utils/MOCK_DATA.csv
new file mode 100644
index 0000000..e89b9f6
--- /dev/null
+++ b/utils/MOCK_DATA.csv
@@ -0,0 +1,11 @@
+id,first_name,last_name,email,gender,ip_address
+1,Rowney,Vanlint,rvanlint0@archive.org,Male,166.243.73.22
+2,Granny,Zecchetti,gzecchetti1@toplist.cz,Bigender,76.2.20.212
+3,Elena,Quilkin,equilkin2@artisteer.com,Female,206.153.61.10
+4,Rob,Kilkenny,rkilkenny3@spiegel.de,Genderqueer,56.156.35.222
+5,Alayne,Sleit,asleit4@si.edu,Female,105.12.142.0
+6,Arleta,Radsdale,aradsdale5@psu.edu,Female,20.128.1.2
+7,Maximilian,Oswick,moswick6@hc360.com,Male,241.240.199.79
+8,Gil,Chinnick,gchinnick7@slashdot.org,Male,2.145.45.118
+9,Galen,Goulter,ggoulter8@sakura.ne.jp,Male,37.93.133.252
+10,Samara,Benka,sbenka9@nydailynews.com,Female,225.2.115.39
diff --git a/utils/converter.js b/utils/converter.js
index c291270..2a00f2c 100644
--- a/utils/converter.js
+++ b/utils/converter.js
@@ -1,4 +1,5 @@
 const fs = require('fs')
+const path = require('path')
 
 const csvToJson = (csv) => {
   const lines = csv.split(/\r\n|\n/)
@@ -17,6 +18,8 @@ const csvToJson = (csv) => {
 }
 
 exports.readFile = async (pathFile) => {
+  const checkExt = path.extname(pathFile)
+  if (checkExt !== '.csv') throw new Error('Wrong extension file')
   const result = new Promise((resolve, reject) => {
     fs.readFile(`${pathFile}`, 'utf8', (err, data) => {
       if (err) {