When we stop testing?

stop testing these are the main factors.

1. Reduce in defects.
2. Increase in Testing cost.
3. Delivary dates.

We need to check that

1) Whether all the Bugs which were Assigned to developers 
have been fixed .
2) All the documents pertaining to testing have been 
prepared.
3) all the bugs which were in Previous releases have been 
retested .