Which type of data is tested to ensure a program functions correctly under normal operating conditions?

The type of data tested to ensure a program functions correctly under normal operating conditions is valid data. This refers to data that is expected by the program, which adheres to the specified format and meets all the conditions necessary for the software to function as intended. Using valid data allows developers to confirm that the program operates smoothly within the parameters it was designed for, ensuring that expected outcomes are produced without errors.

When testing with valid data, the focus is on regular use cases, reflecting how end-users are anticipated to interact with the program. It helps in validating core functionalities, providing a baseline for performance and reliability. This approach ensures that the program behaves correctly and efficiently when faced with typical, realistic inputs.

Other types of data such as edge case data, erroneous data, and extreme data are useful for specific testing scenarios but primarily focus on boundaries, errors, or limits rather than typical operational conditions. Edge cases check the limits of input processing, erroneous data evaluates how the program handles incorrect inputs, and extreme data investigates how the system reacts under stressful or maximum load conditions, rather than regular usage. These tests are important, but they do not serve to confirm the basic operational integrity of the program like valid data does.