RESUMEN

Unit tests are popular. However, it's an art to write them in a way that specifies a program's behavior well, and it's laborious to write enough of them to have confidence in an implementation's correctness. Symbolic execution techniques can help increase code coverage by finding relevant variations of existing unit tests. These techniques can also automatically generate unit tests from an implementation when no prior unit tests exist. Commercial testing tools are already adopting these techniques.This article is part of a special.