Context. Colossal systems that are evolving are primarily system of systems (SOS). The system of systems are characteristic of functionally independent subsystems. These subsystems exhibit heterogeneity in terms of software or hardware. Each subsystem may reflect heterogeneity in dimensions such as the system complexity, system configuration, programming language and platforms, etc. Exploratory testing (ET) is perceived to be the best for testing such systems. An enhancement to exploratory testing is the session-based test management (SBTM) where several activities form a part of each session. These activities are mainly dependent on tester and the test charter of that session. There is lack of information in existing literature regarding a standard framework to design test charters for exploratory testing which forms the main area of focus of this thesis research.

Objectives. Firstly, to investigate the design of test charters in general. Secondly, to find out the factors influencing the design of test charters. Lastly, to develop a framework to design effective test charters in SOS context.

Methods. A mixed method approach that incorporates both qualitative and quantitative research methods is used. This research includes the quantitative leg of the online survey along with the interviews and literature review that are qualitative in nature. Literature review has been chosen to investigate the test charter design in general. Besides, interviews and online surveys  have been used to research regarding the factors and test charter framework.  Snowball sampling method and convenience sampling method have been used to sample the research data. Moreover, thematic analysis method is used for analyzing the qualitative data while descriptive statistics is used for quantitative data analysis.

Results. The design aspects of test charter are documented, the factors influencing test charter design and the framework for effective test charter design for exploratory testing are presented.

Conclusions. The thesis objectives are fulfilled. The findings on how the test charters are generally designed have helped in gaining insight on the primary elements that constitute a test charter design. Further, investigating the factors influencing the test charter design has helped in knowing the main elements affecting the test charter design. Finally, the main contribution of this thesis, the developed flexible test charter framework for exploratory testing encapsulates variables that should be considered, controlled or varied systematically during the course of testing. It is deemed to act as a guideline for practitioners for effective test charter design.