Generally test engineers involved from entire test life 
cycle i.e, test plan, test case preparation, execution, 
reporting.
generally system testing, regression testing, adhoc testing 
etc

HI

Right from the Requirement Stage.

Types of Test are

1. Fuctional & Non- functional.
2. Regression Test.


s.ramprasad sun_ramprasad@yahoo.com

In testing life cycle a test engineer's involvement will be 
based on the role or designation of the employee in that 
company.  Test leads will involve in preparing test 
planning.  Senior test engineers will involve in preparing 
the test cases and executing the test cases as well if 
permits, and junior testers will involve in test execution, 
reporting, etc.  any test engineer has to perform all kinds 
of testings like build verification or smoke testing, 
retesting, regression testing, system testing, system 
integration testing (black box integration) testing etc.  
Please let me know if i am right or wrong.