This study employed a multi-methods design to investigate the impact of preparation on Chinese test-takers' perceptions of the integrated TOEFL iBT speaking and writing design. Combining results from over 1700 surveys and 10 interviews, it was found that these Chinese test-takers, who are the most vulnerable group in the multimillion testing business, demonstrate notably positive perceptions toward the test demand, target domain reflection, familiarity, and difficulty of integrated tests. A significant difference in perceptions was identified between test-takers who underwent test preparation training and those who did not. Test preparation training, in this research context, played a crucial role in fostering a positive perception change by familiarizing test-takers with testing processes, equipping them with essential skills to address integrated test demands, altering their attitudes toward testing and learning while preparing them for university-level learning. This research challenges traditional assumptions of negative test-taker reactions and highlights the positive impact of structured test preparation. The findings provide valuable insights into test-takers' perceptions, particularly from a significant demographic -- Chinese test-takers -- and contribute to the construct validity and washback evidence. These insights further support the critical interpretation and use of TOEFL iBT scores for high-stakes admission decisions, highlighting the impact on test-takers whose lives and success hinge on test outcomes.