  Context: While many companies conduct their software testing activities
in-house, many other companies outsource their software testing needs to other
firms who act as software testing service providers. As a result, Testing as a
Service (TaaS) has emerged as a strong service industry in the last several
decades. In the context of software testing services, there could be various
challenges (e.g., during the planning and service delivery phases) and, as a
result, the quality of testing services is not always as expected. Objective:
It is important, for both providers and also customers of testing services, to
assess the quality and maturity of test services and subsequently improve them.
Method: Motivated by a real industrial need in the context of several testing
service providers, to assess the maturity of their software testing services,
we chose the existing CMMI for Services maturity model (CMMI-SVC), and
conducted a case study using it in the context of two Turkish testing service
providers. Results: The case-study results show that maturity appraisal of
testing services using CMMI-SVC was helpful for both companies and their test
management teams by enabling them objectively assess the maturity of their
testing services and also by pinpointing potential improvement areas.
Conclusion: We empirically observed that, after some minor customization,
CMMI-SVC is indeed a suitable model for maturity appraisal of testing services.
