Validation, Verification and Testing

Validation

Validation is an automatic check that data is reasonable and sensible before it is processed. It cannot prove the data is correct, only that it is acceptable. Common validation checks include:

• Range check — value falls between limits, e.g. a month from 1 to 12
• Length check — a set number of characters, e.g. an 8-digit ID
• Type check — data is of the right type, e.g. only digits
• Presence check — a required field is not left empty
• Format check — data follows a pattern, e.g. a date as DD/MM/YYYY

Verification

Verification checks that data has been entered accurately and matches the original source. Two common methods are double entry (typing data twice and comparing) and a visual check (reading it against the source).

Testing

Testing runs a program with chosen test data to check it works. Designers use normal data (accepted), abnormal data (rejected), extreme data (at the edge of the range) and boundary data (values on the exact limit).