  The recent active development of Internet of Things (IoT) solutions in
various domains has led to an increased demand for security, safety, and
reliability of these systems. Security and data privacy are currently the most
frequently discussed topics; however, other reliability aspects also need to be
focused on to maintain the smooth and safe operation of IoT systems. Until now,
there has been no systematic mapping study dedicated to the topic of
interoperability and integration testing of IoT systems specifically;
therefore, we present such an overview in this study. We analyze 803 papers
from four major primary databases and perform detailed assessment and quality
check to find 115 relevant papers. In addition, recently published testing
techniques and approaches are analyzed and classified; the challenges and
limitations in the field is also identified and discussed. Research trends
related to publication time, active researchers, and publication media are
presented in this study. The results suggest that studies mainly focus only on
general testing methods, which can be applied to integration and
interoperability testing of IoT systems; thus, there are research opportunities
to develop additional testing methods focused specifically on IoT systems, so
that they are more effective in the IoT context.
