So it boils down to "show me your code" and then "please write a few test examples". To staff up a cheap coding sweatshop this method is good-enough.
In most cases an applicant must be able to read English (to google some code to copy-paste and occasionally search through documentation) and able to install and run Eclipse.
The real problem with hiring is that a HR middleman is ignorant and can't tell a good code form a restaurant menu. So he must give a very few simple exercises from common text-books with known answers.
The even bigger problem is that almost no one needs coders, everyone wants programmers which is a complete different set of analytical and engineering skills.
Coding is just a process of translation of a ready-made by someone else, poorly understood (if at all) specifications into a spaghetti [Java] code by calling poorly understood methods of ready-made classes, coded by someone else.
Programming is a process of understanding and describing reality (in terms of design documents, protocol specifications, and then, least importantly, source code in a several languages).
The criteria of success for a coder, btw, is when it just compiles (unit-tests? what unit-tests?) by the industry-strength most advanced compiler of the most sophisticated industry standard static-typing language (static typing is a guarantee from stupid errors, everyone knows) which is even verified to run correctly on the most advanced VM which incorporates millions of man-hours of optimizations, unless.. Never mind.
Success of a programmer is when it, like nginx or Plan9 or OpenBSD, is good-enough.)