Prepare or Design Test data in Software Testing is considering following categories,
What is Test Data?
Test data is actually the input given to a software program. It represents data that affects or is affected by the execution of the specific module. Some data may be used for positive testing, typically to verify that a given set of input to a given function produces an expected result. Other data may be used for negative testing to test the ability of the program to handle unusual, extreme, exceptional, or unexpected input. Poorly designed testing data may not test all possible test scenarios which will hamper the quality of the software.
Test data set examples:
1) No data: Run your test cases on blank or default data. See if proper error messages are generated.
2) Illegal data format: Make one data set of illegal data format. The system should not accept data in invalid or illegal format. Also, check proper error messages are generated.
3) Boundary Condition dataset: Dataset containing out of range data. Identify application boundary cases and prepare data set that will cover lower as well as upper boundary conditions.
4) This data set should be large in volume to perform performance, load and stress testing
5) Valid data set: Create it to check if the application is functioning as per requirements and valid input data is properly saved in database or files.
6) Invalid data set: Prepare invalid data set to check application behavior for negative values, alphanumeric string inputs. This way creating separate datasets for each test condition will ensure complete test coverage.