The Perl garbage collector uses simple reference counting during the normal
execution of a program. This means that cycles or unweakened references in other
parts of code can keep an object around for longer than intended. To help avoid
this problem, the reference count of a new object from its class constructor
ought to be 1. This way, the caller can know the object will be properly
DESTROYed when it drops all of its references to it.

Test::Refcount provides two test functions to help ensure this property holds
for an object class, so as to be polite to its callers.

If the assertion fails; that is, if the actual reference count is different to
what was expected, a trace of references to the object can be printed, if Marc
Lehmann's Devel::FindRef module is installed. This may assist the developer in
finding where the references are.

WWW: https://metacpan.org/release/Test-Refcount