Sagar Sen



Sagar Sen is research scientist at Simula Research Laboratory, Norway. His research interests are in adapting research in software testing, formal methods, and visualization to help improve quality of industrial software systems. He likes designing empirical studies to understand the needs and study the effectiveness of using tools from research in industrial settings. His current project concerns the information system at the Norwegian Customs and Excise department


Testing data-intensive systems is paramount to increase our reliance on e-governance services. An incorrectly computed tax can have
catastrophic consequences in terms of public image. Testers at Norwegian Customs and Excise reveal that faults occur from interactions between
database features such as eld values. Taxation rules, for example, are triggered due to an interaction between 10,000 items, 88 country groups,
and 934 tax codes. There are about 12.9 trillion 3-wise interactions. Finding interactions to uncover speci c faults is like nding a needle in a
haystack. Can we surgically generate a test database for interactions that interest testers? We address this question with a methodology and
tool Faktum to automatically populate a test database that covers all T-wise interactions for selected features. Faktum generates a constraint
model of interactions in Alloy and solves it using a divide-and-combine strategy. Our experiments demonstrate scalability of our methodology
and we project its industrial applications.