Test migration to jest by hand

Apparently using regular expressions is way easier.

test/luhnCheck/luhnCheck.js

@@ -0,0 +1,11 @@
+const luhnCheck = num => {
+let arr = (num + '')
+.split('')
+.reverse()
+.map(x => parseInt(x));
+let lastDigit = arr.splice(0, 1)[0];
+let sum = arr.reduce((acc, val, i) => (i % 2 !== 0 ? acc + val : acc + (val * 2) % 9 || 9), 0);
+sum += lastDigit;
+return sum % 10 === 0;
+};
+module.exports = luhnCheck;