  The current development of the Internet of Things (IoT) technology poses
significant challenges to researchers and industry practitioners. Among these
challenges, security and reliability particularly deserve attention. In this
paper, we provide a consolidated analysis of the root causes of these
challenges, their relations, and their possible impacts on IoT systems' general
quality characteristics. Further understanding of these challenges is useful
for IoT quality engineers when defining testing strategies for their systems
and researchers to consider when discussing possible research directions. In
this study, twenty specific features of current IoT systems are discussed,
divided into five main categories: (1) Economic, managerial and organisational
aspects, (2) Infrastructural challenges, (3) Security and privacy challenges,
(4) Complexity challenges and (5) Interoperability problems.
