Experienced IT specialists don’t need to hear it from others to know that even a very well tested product can become non-operational after deployment to the production environment.
Accordingly, it is a good practice to run existing regression tests in the production environment. We employ the CRUD method in our projects in order to split automated tests into groups (CRUD is an abbreviation that stands for Create/Read/Update/Delete).
Most often, only R-tests can be performed in the production environment, e.g. tests that do not change any data. Despite this limitation, test automation in the production environment is sometimes a critical step in releasing a product.