When a software failure occurs in the field, it is often difficult to reproduce. Guided by a memory dump at the moment of failure (a “core dump”), our RECORE test case generator searches for a series of events that precisely reconstruct the failure from primitive data. Applied on seven non-trivial Java bugs, RECORE reconstructs the exact failure in five cases without any runtime overhead in production code.

Manual debugging is driven by experiments—test runs that narrow down failure causes by systematically confirming or excluding individual factors. The BUGEX approach leverages test case generation to systematically isolate such causes from a single failing test run—causes such as properties of execution states or branches taken that correlate with the failure. Identifying these causes allows for deriving conclusions as: “The failure occurs whenever the daylight savings time starts at midnight local time.” In our evaluation, a prototype of BUGEX precisely pinpointed important failure explaining facts for six out of seven real-life bugs.

Why does my program crash?"--This ever recurring question of software debugging drives the developer during the analysis of the failure. Complex defects are impossible to automatically identify; this can only be left to human judgment. But what we can do is empower the developer to make an informed decision, by helping her understand the failure. To fully comprehend a failure, one may need to consider many different aspects such as the range of the input parameters and the program's structure and runtime behavior. I propose an approach that gathers a variety of such facts from a given failing execution. To examine the correlation of those facts to the failure, it produces additional executions that differ in as few facts as possible. Then the approach creates generalizations and abstractions over the correlating facts. These explain different aspects of the failure and thus help the developer understand and eventually fix the underlying defect.