Perl module that verifies code hasn't left circular references

 Test::Memory::Cycle checks for memory leaks and circular memory
 references. It's a thin Test::More-compatible wrapper around Lincoln
 Stein's Devel::Cycle module.
 .
 Perl's garbage collection has one big problem: Circular references
 can't get cleaned up. A circular reference can be as simple as two
 reference that refer to each other. Test::Memory::Cycle is built on
 top of Devel::Cycle to give you an easy way to check for these
 circular references. You can also use memory_cycle_exists() to make
 sure that you have a cycle where you expect to have one.