Test suites, just like the applications they are testing, evolve throughout their lifetime. One of the main reasons for test-suite evolution is test obsolescence: test cases cease to work because of changes in the code and must be suitably repaired. There are several reasons why it is important to achieve a thorough understanding of how test cases evolve in practice. In particular, researchers who investigate automated test repair - an increasingly active research area - can use such understanding to develop more effective repair techniques that can be successfully applied in real-world scenarios. More generally, analyzing testsuite evolution can help testers better understand how test cases are modified during maintenance and improve the test evolution process, an extremely time consuming activity for any nontrivial test suite. Unfortunately, there are no existing tools that facilitate investigation of test evolution. To tackle this problem, we developed TestEvol, a tool that enables the systematic study of test-suite evolution for Java programs and JUnit test cases. This demonstration presents TestEvol and illustrates its usefulness and practical applicability by showing how TestEvol can be successfully used on real-world software and test suites. Demo video at http://www.cc.gatech.edu/ ∼orso/software/testevol/. © 2013 IEEE.