Migrated tests to jest

Used jest-codemods to migrate, will have to pass everything by hand before we can merge.

test/takeWhile/takeWhile.js

@@ -1,5 +0,0 @@
-const takeWhile = (arr, func) => {
-for (const [i, val] of arr.entries()) if (func(val)) return arr.slice(0, i);
-return arr;
-};
-module.exports = takeWhile;