Profile

My research focuses on refactoring and test quality assurance, specifically the impact analysis of refactoring to improve software quality and test efficiency. I am actively analyzing refactoring techniques applied to test code to enhance test quality. Additionally, I am involved in multiple international collaborative research projects, working closely with researchers from universities in the Netherlands, China, and Canada.
I also have hands-on experience as a QA Engineer, specializing in test quality assurance and test automation. Motivated by a desire to solve challenges discovered in real-world development and to contribute to the overall quality of software in society, I have decided to pursue a Ph.D.

Major publications

• How Does Test Code Differ From Production Code in Terms of Refactoring? An Empirical Study
  Kosei Horikawa, Yutaro Kashiwa, Bin Lin, Kenji Fujiwara, Hajimu Iida
  The 41st International Conference on Software Maintenance and Evolution (ICSME2025 NIER Track).

• An Empirical Investigation into Maintenance of Load Testing Scripts
  Ibuki Nakamura, Kosei Horikawa, Brittany Reid, Yutaro Kashiwa, Hajimu Iida
  The ACM/IEEE International Symposium on Empirical Software Engineering and Measurement (ESEM2025 ERVT Track).