Micro-execution is the ability to run any code segment in isolation. Implementations for micro-execution of code segments are described. A test engine determines an effective address of a memory operation of an instruction of an executable program. The test engine determines, prior to performing the memory operation and based on a memory policy, that the effective address is to be replaced with a replacement address. Based on determining that the effective address is to be replaced, the test engine allocates the replacement address and executes the instruction based on the allocated replacement address.