Test Data should be designed.

• Data, that we input to application-under-test, control business logic flow. To explore every branch of the flow, we need to choose data accordingly.
• Wrong data trigger error-handling functionalities. To try and see all of them, we need to create data in different equivalence classes.
• Test Data from Production might contain non-disclosing information
• Test Data from Production reflect only “happy path” scenarios

Test Data should be manageable.

• Test Data must be stored in files with organized structure: XLS, XML
• Within a project, Test Data format should be standardized 
• Test Data should not be duplicated
• Volumes of Test Data should be indexed
• Large volumes of Test Data need to be stored in database
• For versioned applications, Test Data should be version-controlled too

Test Data should be shared.

• Test Data is an asset for the entire team
• Test Data should be reusable