What is the purpose of invalid data in testing?

The primary purpose of using invalid data in testing is to evaluate the code's validation routines. When developing software or applications that handle data, it's crucial to ensure that the system can accurately identify and appropriately respond to data that does not conform to expected formats or standards. By introducing invalid data, developers can verify that the application correctly triggers error messages, implements safety checks, and prevents the processing of erroneous information. This verification helps maintain data integrity and enhances the overall robustness and reliability of the software.

In this context, the other options focus on different aspects of data handling and analysis. Checking data visualization involves assessing how well the data is represented graphically, which is distinct from testing validation routines. Analyzing user experiences is oriented toward understanding user interactions with the application, rather than focusing on how the application manages data inputs. Improving data storage pertains to optimizing how data is saved and retrieved, which does not align directly with the immediate objectives of validating data integrity through testing.