CxxTest is the Unit Testing framework used in ObveRsive and can be found at http://cxxtest.sourceforge.net/
CxxTest is much easier to use than other testing frameworks because it uses code generation to dynamically create test runners and other facilities. Competing frameworks typically require extremely complicated setups and advanced compilers with RTTI and other C++ "magic" to even do basic testing. CxxTest requires nothing more than Python or Perl and the writing of a header file.