Quality Code: Software Testing Principles, Practices, and Patterns

Some History

At the dawn of the Computing Age, software ran one instruction at a time. Early operating systems added some level of parallelism, but user-written programs still executed one at a time, only taking a break so that the operating system could function. At first, that break only occurred when the program allowed it, known as cooperative multitasking. But this wasn’t enough, so the concept was extended to run multiple user programs in much the same way, encapsulated in the concept of a process. Processes were segregated into different address spaces and executed in parallel by orchestration of the operating system through a mechanism called preemptive multitasking. Each process had its own dedicated memory and other resources. They ...