If you develop an
ATK application but do not have the luxury of a separate test-database, and can only test against actual databases, it is not safe to run testcases that actually add records to the database. Even though testcases can be built to clean-up testdata afterwards, this is not without risk. For instance, when a testcase breaks halfway through the code with a PHP parse error, any testdata that was already added will stay there. Besides the fact that this can break any future executions of your testcase, the testrecord stays in the live database and possibly break the live site.
This is where the atkMockDb kicks in

.