This paper examines (1) teacher candidates' knowledge of recent migration trends and language accreditation policies, (2) their attitudes towards language testing for migration, and (3) changes in their perceptions after exposure to training and migrant testimonies. Conducted over two years (2021-2023), this mixed-methods study involved 395 candidates from Spain (166), Poland (125), and the Czech Republic (104). Participants completed a migration data test and a pre-survey employing The Language Accreditation for Migration Attitude s Scale (LAMAS), an ad-hoc ten-item scale with three dimensions. The intervention included a comprehensive learning module with readings and visual resources, and exposure to migrant testimonies, followed by a LAMAS-based post-survey, classroom discussions, and reflective reports. Data analysis via SPSS and QDA Miner revealed significant correlations between attitudes and home countries (Kruskal-Wallis test), and notable attitude changes post-treatment (Wilcoxon Sign-Ranked test). The study underscores the enhanced awareness and understanding of language assessment challenges in migration, highlighting the need to integrate these issues into teacher training programs.