Test migration to jest by hand

Apparently using regular expressions is way easier.

test/sortedLastIndex/sortedLastIndex.js

@@ -0,0 +1,6 @@
+const sortedLastIndex = (arr, n) => {
+const isDescending = arr[0] > arr[arr.length - 1];
+const index = arr.reverse().findIndex(el => (isDescending ? n <= el : n >= el));
+return index === -1 ? 0 : arr.length - index;
+};
+module.exports = sortedLastIndex;