Dr. Valentin Dallmeier
Postdoc

Who I Am

WebMate

Phd Thesis

New: My thesis won the Ernst Denert Award for Software Engineering 2010. There is a press release that describes the prize.

My thesis introduces a novel approach to modeling the behavior of programs at runtime. We leverage the structure of object-oriented programs to derive models that describe the behavior of individual objects. Our approach mines object behavior models, finite state automata where states correspond to different states of an object, and transitions are caused by method invocations. Such models capture the effects of method invocations on an object's state. To our knowledge, our approach is the first to combine the control-flow with information about the values of variables. Our ADABU tool is able to mine object behavior models from the executions of large interactive java programs.

To investigate the usefulness of our technique, we study two different applications of object behavior models:

• Mining Specifications Many existing verification techniques are difficult to apply because in practice the necessary specifications are missing. We use ADABU to automatically mine specifications from the execution of test suites. To enrich these specifications, our TAUTOKO tool systematically generates test cases that exercise previously uncovered behavior. Our results show that, when fed into a typestate verifier, such enriched specifications are able to detect more bugs than the original versions.
• Generating Fixes We present PACHIKA, a tool to automatically generate possible fixes for failing program runs. Our approach uses object behavior models to compare passing and failing runs. Differences in the models both point to anomalies and suggest possible ways to fix the anomaly. In a controlled experiment, PACHIKA was able to synthesize fixes for real bugs mined from the history of two open-source projects.

The complete version of my thesis is available for download at the publication page.

Testfabrik AG

The work I did in the webmate project has lead to a startup called Testfabrik AG. More information is available at the company homepage.

• Layout testing: webmate is able to automatically compare the layout of a web page in different browsers and reveals a list of cross-browser deviations.
• Regression testing: webmate is also able to compare the layout of two different versions of a web page to find out what effects a potentially minor change to the web page has.
• Network analysis: webmate captures all the traffic between a browser and the server in an http archive file and is able to analyse performance and http errors.
• Javascript errors: webmate logs all javascript errors that occur on a page.

Publications

Projects

• WebMate: A project for testing web aplications. The project homepage is available here.
• Ample: A project for automatic defect localization of Java Programs. The project homepage is available here.
• Adabu: Mining models that describe the behavior of objects. The project homepage is available here.
• iBugs: Purpose of the iBugs project is to mine large numbers of bugs from a project's version history and provide compilable tests for all versions. The project homepage is available here here.
• Tautoko: Generating test cases to enhance object behavior models by mutating the regression test suite. The project homepage is available here.

Contact