  A recent research trend has emerged to identify developers' emotions, by
applying sentiment analysis to the content of communication traces left in
collaborative development environments. Trying to overcome the limitations
posed by using off-the-shelf sentiment analysis tools, researchers recently
started to develop their own tools for the software engineering domain. In this
paper, we report a benchmark study to assess the performance and reliability of
three sentiment analysis tools specifically customized for software
engineering. Furthermore, we offer a reflection on the open challenges, as they
emerge from a qualitative analysis of misclassified texts.
