Increasing test coverage with Hapao

Test coverage is about assessing the relevance of unit tests against the tested application. It is widely acknowledged that software with a ''good'' test coverage is more robust against unanticipated execution, thus lowering the maintenance cost. However, ensuring good quality coverage is challenging, especially since most of the available test coverage tools do not discriminate between software components that require ''strong'' coverage from the components that require less attention from the unit tests. Hapao is an innovative test coverage tool, implemented in the Pharo Smalltalk programming language. It employs an effective and intuitive graphical representation to visually assess the quality of the coverage. A combination of appropriate metrics and relations visually shape methods and classes, which indicates to the programmer whether more effort on testing is required. This paper presents the important features of Hapao by illustrating its application on an open source software.