Testing will start in every stage of the S/W development.

Testinf starts right from requirement analysis

that depends upon the sort of testing.

there are two kinds of testing. 

coventional and unconventional.

unconventional testing is done by the quality assurance 
engineers right from the initial stage of software 
develoment life cycle.

conventional testing is done by the test engineers when 
they get the build from the development section.

Hi,

  Once the Requirements are base lined then only we can go 
for testing the application.


Regards,
Satya.k

Refer V - MODEL for your question.
This model give you all the details of testing & 
development activities.

When to start Testing is tightly coupled with the types of 
SDLC we are foloowing for the project. If it is Waterfall 
model testing is just a phase and starts after the 
Development phase. If it is V&V model testing starts right 
from the begining (Requirements). in cases of Spiral it is 
like starting again and again. So the begining of the 
Testing may vary depeding upon the SDLC model selected for 
the project.

once the requirements are frozen then  we will write the 
test cases. 

 if it is wrong plz correct me..............

ch.s.m.prasad

eid : sri8prasad@gmail.com