  Automatically generating test cases for software has been an active research
topic for many years. While current tools can generate powerful regression or
crash-reproducing test cases, these are often kept separately from the
maintained test suite. In this paper, we leverage the developer's familiarity
with test cases amplified from existing, manually written developer tests.
Starting from issues reported by developers in previous studies, we investigate
what aspects are important to design a developer-centric test amplification
approach, that provides test cases that are taken over by developers into their
test suite. We conduct 16 semi-structured interviews with software developers
supported by our prototypical designs of a developer-centric test amplification
approach and a corresponding test exploration tool. We extend the test
amplification tool DSpot, generating test cases that are easier to understand.
Our IntelliJ plugin TestCube empowers developers to explore amplified test
cases from their familiar environment. From our interviews, we gather 52
observations that we summarize into 23 result categories and give two key
recommendations on how future tool designers can make their tools better suited
for developer-centric test amplification.
