There are some points which indicate that testing is complete:
1-The exit criteria that was mentioned in the test plan document is achieved.
2-when we acheived no. of successful test case execution at a specified level.
2-when rate of bug finding decrease from a specified level.
3-when manager said that ok stop.
4-when we dont have enough time to perform more test and have acheived a specified level of quality.
5-when the cost of fixing a bug ismore then the impact of the bug in the system.