1. A method for automated test case augmentation, the method comprising: receiving, at an automated test augmentation system, a design model and model coverage gap information from a model-based development tool; translating the model coverage gap information into machine-readable mathematical test objective expressions; developing a set of test objective operators by translating the machine-readable mathematical test objective expressions; localizing target operators for the identified coverage gaps within the design model; attaching the test objective operators to target operators of the design model to create a test model; augmenting the test model by propagating test objectives at the target operators to a test node operator of the design model; and executing, by a test generator, the augmented test model to obtain the test cases to cover the coverage gaps and the causes for the model coverage gaps.