Analysing the evolution of testing library usage in open source Java projects
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The document analyzes the evolution of testing library usage in open source Java projects, focusing on popular libraries such as JUnit and Mockito. It highlights the prevalence of simultaneous library use, migration patterns, and the importance of understanding library evolution for developers and maintainers. Key findings indicate that many libraries complement each other, though a small percentage of projects experience migrations between competing libraries.
![Focus
6
Most popular programming language [1]
> 900k of open source Java projects.
[1] According to TIOBE Index for January 2017 h_p://www.1obe.com/1obe-index/
[2] According to h_ps://mvnrepository.com/open-source/tes1ng-frameworks
Most popular Java tes@ng and mocking libraries [2]](https://image.slidesharecdn.com/saner2017-zeroualimigration-170220163714/85/Analysing-the-evolution-of-testing-library-usage-in-open-source-Java-projects-6-320.jpg)
Analysing the evolution of testing library usage in open source Java projects
- 10. Most Frequently Used Tes1ng-related Libraries 10 Considered: 20,688 Java projects on GitHub Excluded: • projects < 2 years • unforked projects • forks • projects not using the selected libraries Retained: 4,532 Java projects
- 11. Dataset 11 Metrics Value Considered Java projects 20,688 Projects using at least one of the considered libraries 4,532 Commits 125,580 Source files 10,033,726 Tes1ng related import statements 31,264,586
- 15. Which libraries are used simultaneously in projects? 15 Mockito EasyMock PowerMock JUnit 100% 7% 12% 23% 4% 32% JUnit TestNG Spring Hamcrest AssertJ 9% 5% TestNG 64% 100% 13% 18% 6% 33% 12% 4% Spring 99% 12% 100% 37% 8% 53% 18% 10% 59% 10% 10% AssertJ 95% 16% 23% 41% 100% 61% Hamcrest 99% 9% 18% 100% 7% 11% 15% Mockito 98% 11% 19% 42% 8% 100% 8% 13% EasyMock 77% 14% 22% 24% 5% 28% 100% 10% 87% 19% 100%PowerMock 99% 9% 23% 47% 13%
- 16. Which libraries are used simultaneously in projects? • JUnit is very frequently accompanied (>94%) by Hamcrest, AssertJ, Spring, Mockito or PowerMock • JUnit is rarely used with compe1tor TestNG (7%) • PowerMock is mostly used as an extension of Mockito (86.5%) 16
- 20. How frequently are libraries used over 1me? 20 Tes1ng and matching libraries -> <- Mocking libraries
- 21. Limita1ons 21 q Open source Java Projects using Maven as the build automa1on tool. q Project’s life1me two years. q Import statements.
- 22. Main Findings 22 • Many libraries are used simultaneously. • Many of the considered libraries complement one another, some are compe1ng. • 5% of the considered projects were subject to library migra1ons.
- 23. Future Work / Open Ques1ons 23 so0ware developer library maintainer How to analyse library evolu1on pa_erns to recommend • when to upgrade to a new library version? • when to migrate to a compe1ng library? • how to upgrade or migrate (e.g. effort & impact)? How to analyse library usage pa_erns to • avoid library migra1on? • facilitate library upgrading? • maximise usage of library func1onali1es? • detect opportuni1es for new func1onali1es?