  Graphical user interfaces (GUIs) are integral parts of software systems that
require interactions from their users. Software testers have paid special
attention to GUI testing in the last decade, and have devised techniques that
are effective in finding several kinds of GUI errors. However, the introduction
of new types of interactions in GUIs (e.g., direct manipulation) presents new
kinds of errors that are not targeted by current testing techniques. We believe
that to advance GUI testing, the community needs a comprehensive and high level
GUI fault model, which incorporates all types of interactions. The work
detailed in this paper establishes 4 contributions: 1) A GUI fault model
designed to identify and classify GUI faults. 2) An empirical analysis for
assessing the relevance of the proposed fault model against failures found in
real GUIs. 3) An empirical assessment of two GUI testing tools (i.e. GUITAR and
Jubula) against those failures. 4) GUI mutants we've developed according to our
fault model. These mutants are freely available and can be reused by developers
for benchmarking their GUI testing tools.
