1. A method of generating a negative test input data, the method comprising: extracting, by a data management device, a set of attributes and a set of attribute properties from a requirement specification; framing, by the data management device, a constraint representation syntax from the extracted set of attribute properties; modeling, by the data management device, a structured diagram from the framed constraint representation syntax and a set of use cases; constructing, by the data management device, a set of path predicates from the structured diagram; determining, by the data management device, one or more attribute classes from the set of path predicates based on an attribute constraint and an attribute dependency; and generating, by the data management device, the negative test input data for the one or more attribute classes.