Effective Perl Programming, 2d ed
published in 2010, has a chapter on testing. It is not a tutorial on basic test techniques. It includes several multi-page examples; and covers topics such as mock objects, test-driven development, and a continuous build system.
Perl Medic, Transforming Legacy Code
ISBN 9780201795264 from 2004, also has a chapter on testing. It provides short introductions to several Test:: modules; and a detailed description of how to build real test code with a well-written 15-page example.