If you are writing test case then you need input data for any kind of test.
Tester may provide this input data at the time of executing the test cases or
application may pick the required input data from the predefined data locations.
The test data may be any kind of input to application, any kind of file that is
loaded by the application or entries read from the database tables. It may be in
any format like xml test data, system test data, SQL test data or stress test
data.
Preparing proper test data is part of the
test setup. Generally testers call it as testbed preparation. In
testbed all software and hardware requirements are set using the predefined data
values.
If you don�t have the systematic approach for building test data while
writing and executing test cases then there are chances of missing some
important test cases. Tester can�t justify any bug saying that test data was not
available or was incomplete. It�s every testers responsibility to create his/her
own test data according to testing needs. Don�t even rely on the test data
created by other tester or standard production test data, which might not have
been updated for months! Always create fresh set of your own test data according
to your test needs.
Sometime it�s not possible to create complete new set of test data for each
and every build. In such cases you can use standard production data. But
remember to add/insert your own data sets in this available database. One good
way to design test data is use the existing sample test data or testbed and
append your new test case data each time you get same module for testing. This
way you can build comprehensive data set.