A method and a test system for specifying a predetermined degree of inconsistency for test data are disclosed. The test system obtains a test policy, which specifies a predetermined degree of inconsistency between write operations and subsequent read operations on a set of data and subsequently receives a request to provide test data to an application. In response to the request to provide test data to the application the test system generates a set of test data including a plurality of entities retrieved from the set of data, based at least in part on the test policy. The test data includes a respective entity that is not consistent with a previous write operation. The test system further provides the set of test data to the application. The application optionally processes the set of test data to produce results, which are used to determine performance of the application.