Embodiments of the invention include methods and systems for improving test case coverage. Aspects of the invention include executing, by a processor, a first test case, where the first test case includes a plurality of system calls to an operating system. Prior to execution of each system call in the plurality of system calls in the first test case, executing, by the processor, a pre-exit instruction. Responsive to execution of the pre-exit instruction, collecting pre-exit system call data regarding each system call in the plurality of system calls for the first test case. The processor executes a post-exit instruction after completion of each system call in the plurality of system calls and responsive to execution of the post-exit instruction, collects post-exit system call data regarding each system call in the plurality of system calls for the first test case.