||The programming tests are basically factoids and riddles (where's the bug, will this code compile, what's the output, etc.) You have to know the language well to do well and vice versa.
They also have general aptitude tests, which are less language specific and measure general problem solving skills. Level of these tests is lower than language specific ones - it's much easier to fix incorrect factoid question than a completetly wrong aptitude test. Having said that, still their tests are one of the best aptitude tests I've seen so far.