Abstract : The adoption of agile approaches has put an increased emphasis on testing,
resulting in extensive test suites. These suites include a large number of tests, in which
developers embed knowledge about meaningful input data and expected properties as oracles.
This article surveys works that exploit this knowledge to enhance manually written tests with
respect to an engineering goal (e.g., improve coverage or refine fault localization). While these
works rely on various techniques and address various goals, we believe they form an emerging
and coherent field of research, which we coin “test amplification”. We devised a first set of
papers from DBLP, searching for all papers containing "test" and "amplification" in their
title. We reviewed the 70 papers in this set and selected the 4 papers that fit the definition
of test amplification. We use them as the seeds for our snowballing study, and systematically
followed the citation graph. This study is the first that draws a comprehensive picture of the
different engineering goals proposed in the literature for test amplification. We believe that
this survey will help researchers and practitioners entering this new field to understand more
quickly and more deeply the intuitions, concepts and techniques used for test amplification.