My PhD addresses the problem of detecting field failures with a new approach to test software systems under conditions that emerge only in production. Ex-vivo approaches detect field failures by executing the software system in the testbed with data extracted from the production environment. In-vivo approaches execute the available test suites in the production environment. We will define autonomic testing that detects conditions that emerge only in production scenarios, generates test cases for the new conditions, and executes the generated test cases in the new scenarios, to detect failures before they occur in production.