  In order to optimize the usage of testing efforts and to assess risks of
software-based systems, risk-based testing uses risk (re-)assessments to steer
all phases in a test process. Several risk-based testing approaches have been
proposed in academia and/or applied in industry, so that the determination of
principal concepts and methods in risk-based testing is needed to enable a
comparison of the weaknesses and strengths of different risk-based testing
approaches. In this chapter we provide an (updated) taxonomy of risk-based
testing aligned with risk considerations in all phases of a test process. It
consists of three top-level classes, i.e., contextual setup, risk assessment,
and risk-based test strategy. This taxonomy provides a framework to understand,
categorize, assess and compare risk-based testing approaches to support their
selection and tailoring for specific purposes. Furthermore, we position four
recent risk-based testing approaches into the taxonomy in order to demonstrate
its application and alignment with available risk-based testing approaches.
