Background: Fitness testing is a commonly applied learning and teaching practice implemented in both secondary and elementary school physical education (PE). Many teachers believe that by using a variety of different tests, they are able to provide students with feedback regarding their fitness status, and furthermore, increase students' willingness to be physically active later in their lives. However, empirical evidence concerning students' affective responses during fitness testing classes is limited. Purpose: The primary aim of the study was to investigate whether students' perceptions of enjoyment and anxiety differed between two different types of fitness testing classes and PE in general. In addition, the measurement invariances over time and between Grade 5 (aged 11-12) and Grade 8 (aged 14-15) groups were determined. Method: A total sample of 645 Finnish Grade 5 (N = 328, 50% boys, mean age = 11.2, SD = 0.36) and Grade 8 students (N = 317, 47% boys, mean age = 14.2, SD = 0.35) participated in the study. Series of multi-group confirmatory factor analyses were conducted to test the level of measurement invariance between general PE and fitness testing classes, and between age groups. Strict factorial invariance was supported for both enjoyment and anxiety scales allowing for latent mean comparisons. Latent mean differences were studied using z-tests. Results: Grade 5 students perceived significantly lower levels of enjoyment and cognitive processes and a higher level of somatic anxiety in fitness testing classes compared to general PE. Additionally, for Grade 8 students, levels of enjoyment and cognitive processes were significantly lower and somatic anxiety and worry higher in fitness testing classes than in general PE. Furthermore, enjoyment was significantly higher, and cognitive processes, somatic anxiety and worry lower among Grade 5 students compared with Grade 8 students in both contextual PE and during fitness testing class. Conclusion: Results of this study indicate that students' perceptions of enjoyment were lower in fitness testing classes compared to PE in general. Additionally, students perceived lower levels of cognitive anxiety and higher levels of somatic anxiety in fitness testing classes than in general PE. It is noteworthy that students might not significantly dislike fitness testing per se but instead have significantly more positive affects towards PE in general. Generally, practitioners conducting fitness testing lessons are encouraged to embrace different strategies such as fostering basic psychological needs or promoting mastery climate to facilitate enjoyment and diminish anxiety.