The enactment of the General Data Protection Regulation (GDPR) in 2018 forced any organization that collects and/or processes EU-based personal data to comply with stringent privacy regulations. Software organizations have struggled to achieve GDPR compliance both before and after the GDPR deadline. While some studies have relied on surveys or interviews to find general implications of the GDPR, there is a lack of in-depth studies that investigate compliance practices and compliance challenges of software organizations. In particular, there is no information on small and medium enterprises (SMEs), which represent the majority of organizations in the EU, nor on organizations that practice continuous integration. Using design science methodology, we conducted an in-depth study over the span of 20 months regarding GDPR compliance practices and challenges in collaboration with a small, startup organization. We first identified our collaborator's business problems and then iteratively developed two artifacts to address those problems: a set of operationalized GDPR principles, and an automated GDPR tool that tests those GDPR-derived privacy requirements. This design science approach resulted in four implications for research and for practice. For example, our research reveals that GDPR regulations can be partially operationalized and tested through automated means, which improves compliance practices, but more research is needed to create more efficient and effective means to disseminate and manage GDPR knowledge among software developers.