Migrated tests to jest

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

test/memoize/memoize.js

@@ -1,9 +0,0 @@
-const memoize = fn => {
-const cache = new Map();
-const cached = function(val) {
-return cache.has(val) ? cache.get(val) : cache.set(val, fn.call(this, val)) && cache.get(val);
-};
-cached.cache = cache;
-return cached;
-};
-module.exports = memoize;