fake-repositories

问题 I've been trying to push my mentallity when developing at home to be geared more towards TDD and a bit DDD. One thing I don't understand though is why you would create a fake repository to test against? I haven't really looked into it much but surely the idea of testing is to help decouple your code (giving you more flexability), trim down code needed and bring down the number of bugs. So can someone fill in my foolish brain as to why some like to test fake repositories? I would have thought