Test smell refactoring revisited: What can internal quality attributes and developers’ experience tell us?

Abstract

Test smells represent a set of poorly designed tests, which can harm test code maintainability. Although fundamental steps to understand test smells have been taken, there is still an evident lack of studies evaluating the impact of test smell refactoring from the perspective of internal quality attributes, such as size, cohesion, coupling, and complexity. In addition, the literature still lacks research that addresses the difficulties developers face during test smell refactoring. This article investigates the impact of test smell refactoring from a developer’s perspective, considering the internal quality attributes and the background experience. We investigated the perceptions and difficulties encountered by 20 developers while removing five types of test smells in four open-source projects over two months. Through this study, we analyzed: (i) the impact that test smell refactoring has on internal quality attributes; (ii) the developers’ perception of test smells as actual problems within software systems; (iii) the main difficulties developers face during test smell refactoring; (iv) the influence of developers’ experience on assertiveness and refactoring time of test smells, and (v) the effects of refactoring on the test smell density. Our findings can help developers design a prioritization scheme for test smell refactoring and make them aware of the real benefits of test smell refactoring.