Identifying program, test, and environmental changes that affect behaviour

Developers evolve a software system by changing the pro-gram source code, by modifying its context by updating li-braries or changing its configuration, and by improving its test suite. Any of these changes can cause differences in pro-gram behaviour. In general, program paths may appear or disappear between executions of two subsequent versions of a system. Some of these behavioural differences are expected by a developer; for example, executing new program paths is often precisely what is intended when adding a new test. Other behavioural differences may or may not be expected or benign. For example, changing an XML configuration file may cause a previously-executed path to disappear, which may or may not be expected and could be problematic. Fur-thermore, the degree to which a behavioural change might be problematic may only become apparent over time as the new behaviour interacts with other changes. We present an approach to identify specific program call dependencies where the programmer’s changes to the pro-gram source code, its tests, or its environment are not ap-parent in the system’s behaviour, or vice versa. Using a static and a dynamic call graph from each of two program versions, we partition dependencies based on their presence in each of the four graphs. Particular partitions contain de-pendencies that help a programmer develop insights about often subtle behavioural changes