Testing Python: Applying Unit Testing, TDD, BDD and Acceptance Testing

Chapter 1

A History of Testing

THE IDEA OF testing is one that has evolved over many years in the development community. Developers used to have much less focus on testing up front and just wrote code and dealt with any problems that arose by quickly writing fixes after a testing period at the end of a project. That isn't to say that there weren’t developers out there who were writing code that was trouble free when out in the wild, but on the whole, writing code without tests in general is going to lead to problems down the line. There were also cases where testing was a priority, such as code that could cause destruction or the possibility of a person dying. In such circumstances there would be rigorous testing, but this was very much the exception rather than the rule.

The first real change in ideology came with improvements in technology and the resulting development pressures that came with it. When computers were slower, code modification cycles took much longer. Even a simple program could take tens of minutes to build, and large projects could take hours. This resulted in a batch development process where people spent a great deal of time pouring over code, figuring out issues, and then making sets of changes. The amount of time spent verifying changes to the code was comparatively small compared with the cycle time.

As computers became faster, compilation times shrank and development cycle times correspondingly shrank. It became feasible to make small changes to code, ...