Migrated tests to jest

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

test/transform/transform.js

@@ -1,2 +0,0 @@
-const transform = (obj, fn, acc) => Object.keys(obj).reduce((a, k) => fn(a, obj[k], k, obj), acc);
-module.exports = transform;