The outbreak of COVID-19 has posed a sudden and unprecedented change to the educational system. This study investigated the impact of this sudden change on EFL learners' perceptions of assessment in a technology-enhanced learning environment. Assessment dimensions such as affective factors, validity, reliability, practicality, security and pedagogy were explored through an online questionnaire administered among 345 Iranian EFL learners and a focus-group interview with 17 learners. In addition, through a quasi-experimental design, the study compared the learners' academic achievements of online and in-person classrooms during the COVID-19 outbreak. The findings revealed that the flexibility of online assessment, immediate feedback and encouraging self-regulated learning are among the advantages and technical problems, technology dependence and technology literacy are among the challenges of technology-enhanced assessment. The findings indicated that while technology-enhanced assessment has a positive impact on learners' performances, learners have various attitudes towards e-assessment that need to be addressed in future studies.