What is some advice in organizing automated testing so that they do not interfere with each other? For example eventually automated tests can get out of control if it is run on the same data. Obviously a new instance is required but does your automated test have an additional testing suite to set up preliminary data and then clean the instance after each test or set of tests?
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The easiest way is to create database scripts which clean up and reset data whenever you're running a test suite. That way, you'll have the same starting point every time - so that excludes unexpected data as a reason your tests fail.