ISTQB stands for International Software Testing Qualifications Board. This organization was created in 2002 in Scotland. This organization tests those for software. They use a checklist like a syllabus in order to determine those who qualify. There is both a foundation level and advanced level. When the criteria has been completed, then the testing should come to a halt. The test plan and strategy include the completion criteria.
There are a few other ways in which the testing can be stopped. These include if no critical bugs are found, a point is reached based on the requirements being reached, and also the cases for the tests are finished and they reached a certain percentage for passing. Even though it may seem like a simple question, actually testing continues at all times.