Migrated tests to jest

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

test/merge/merge.js

@@ -1,10 +0,0 @@
-const merge = (...objs) =>
-[...objs].reduce(
-(acc, obj) =>
-Object.keys(obj).reduce((a, k) => {
-acc[k] = acc.hasOwnProperty(k) ? [].concat(acc[k]).concat(obj[k]) : obj[k];
-return acc;
-}, {}),
-{}
-);
-module.exports = merge;