What is negative testing in software testing?

Overview

Software testing is an essential part of the Software Development Life Cycle (SDLC) to ensure the quality of a software product. Out of the several software testing techniques employed, in this shot we will discuss the negative testing technique.

Definition

The negative testing technique is used to certify that software doesn’t fail or emit abnormal behavior when invalid input is provided, as displayed in the image below:

Process

Make a series of negative test cases.
Test the cases and list the results.

The following table lists the usual negative test case categories and their examples:

Test case categories	Description	Example
Required Field Test	All required fields of the form must be filled before submitting.	Consider a web application that has several required fields on a form. A good negative test case would be to try submitting the form with an unfilled required field.
Data & Field Correspondence Test	Required data type and the data type of the data in the field must match.	Consider a text field intended for storing a phone number. A good negative test case would be to try entering non-numeric characters in the field.
Data Bound Test	The size of the data in the field should adhere to the upper and lower bounds.	Consider a text field that takes a person’s first name as input. The upper and lower bound of the characters is defined to be 30 and 2 characters, respectively. A good test case would be to enter data that is greater than 30 characters or less than 2 characters.
Numeric Bound Test	The numeric input must be in range.	Consider a numeric field that must only contain positive integers. A good negative test case would be to enter negative integers.
Reasonable Data Test	The input data must be logically reasonable.	Consider a field that is used to store a person’s age. Entering 500 as a person’s age is absurd. Therefore, a good negative test case would be to enter an age greater than a specified threshold.
Web Session Test	The user must be authenticated before interacting with the data.	Consider a web application that requires the user to be logged in to submit some data. A good negative test would be to try submitting the data without logging in.

Advantages

Reduces software vulnerabilities considerably.

Disadvantages

Time consuming and tedious process.
Can lead to excessive negative testing.