The testing pyramids
Clean code, coding standards, and peer reviews are essential parts of a good application, but they are not the only ones. In fact, a good and reliable application is not only the source of good development but also the result of a good level of testing coverage available within the application.
Testing covers a very large spectrum. Some companies do very minimal tests, letting their end users be the actual testers by shipping them new code to look for bugs and errors, while others invest time and budgets in developing comprehensive sets of tests and adding them to their processes.
Even if companies invest different amounts of time in testing, all developers can at least agree that increased testing can, on average, result in fewer bugs being shipped to the user and a more flexible application.
Multiple levels of testing can be developed for an application, and they are divided into layers that together form a pyramid (hence the name testing pyramid).
...
