"When to stop testing" is one of the most difficult questions to a test engineer.
The following are few of the common Test Stop criteria:

1. All the high priority bugs are fixed.
2. The rate at which bugs are found is too small.
3. The testing budget is exhausted.
4. The project duration is completed.
5. The risk in the project is under acceptable limit.

Practically, we feel that the decision of stopping testing is based on the level of the risk acceptable to the management. As testing is a never ending process we can never assume that 100 % testing has been done, we can only minimize the risk of shipping the product to client with X testing done. The risk can be measured by Risk analysis but for small duration / low budget / low resources project, risk can be deduced by simply: -

• Measuring Test Coverage.
• Number of test cycles.
• Number of high priority bugs.

2) All the Test cases needs to be complete 100% Pass rate

3) All the Failed test cases needs to complte re-test

4) The project duration  and budget is completed