Metamorphic relations are presented as an effective method for enhancing machine learning model testing by expanding test coverage beyond what is achievable through standard data collection. These relations involve altering existing data in ways that maintain the original label, such as rotating images or adjusting color intensity, to address the test oracle problem where determining the correct output for a given input is challenging due to data scarcity and annotation costs. By applying metamorphic relations, such as image augmentations and temporal relations, models can be more robustly tested, ensuring they behave according to specifications even when subjected to various transformations. This approach not only multiplies available test data but also highlights that training with data augmentations does not guarantee model robustness, making testing essential for identifying potential bugs and enhancing model reliability. The concept has been successfully applied in various domains, including medical imaging and autonomous driving, revealing significant insights into model behavior and potential errors.