Migrated tests to jest

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

test/URLJoin/URLJoin.js

@@ -1,10 +0,0 @@
-const URLJoin = (...args) =>
-args
-.join('/')
-.replace(/[\/]+/g, '/')
-.replace(/^(.+):\//, '$1://')
-.replace(/^file:/, 'file:/')
-.replace(/\/(\?|&|#[^!])/g, '$1')
-.replace(/\?/g, '&')
-.replace('&', '?');
-module.exports = URLJoin;