While testing a software application, testers often evaluate its features and functionality based on predefined business requirements. The testers also need to perform a variety of tests to check the effectiveness of the application by keeping users engaged. But they must perform both positive and negative testing to evaluate the quality of the software more accurately. The combination of positive and negative testing further helps them to enhance test coverage.
Initially, the testers perform positive or happy path testing to check if the application behaves in the expected way by providing positive inputs. The primary objective of positive testing is to check if the application behaves or functions as it is supposed to do. At the same time, the testing professionals also need to perform negative testing or error path testing to check if the application behaves in the expected manner by providing negative inputs. The primary objective of negative testing is to check if the software is not functioning in a way as it is not supposed to do.
The negative tests help testing professionals to check if the application is smart enough to handle the invalid data inputted by users. For instance, the testers can include negative tests in the test suite to check if the software compels users to create passwords with both alphabets and numbers. Likewise, they can also perform negative tests to prevent users from submitting invalid input and wrong type of data. There can further customize the negative test cases according to varying situations and scenarios.
Why Testing Professionals Must Perform Negative Testing?
Prevent Cyber Criminals:
Most cyber criminals nowadays execute targeted security attacks by taking advantage of the faults or loopholes in software applications. Negative testing helps testers to identify the faults or errors that may result in system failure in the longer run. Based on the negative testing results, the testing professionals can prevent the cyber criminals from submitting malicious data or script as user input.
Identify the Weakness/shortcomings of an application:
The testers can further identify the weaknesses or shortcomings of an application by performing negative testing. As mentioned earlier, they need to provide invalid input to ensure that the application is not functioning any unexpected way. Hence, they can easily eliminate chances of exploitation in future by making the software more robust.
Eliminate the Chances of Security Breaches:
Negative testing further helps testers to keep the application secure by eliminating chances of security breaches. For instance, the testing professionals can use negative test scenarios to ensure that a web application is accessible only to the authorized users who have logged in to the system by using their credentials. They can take advantage of the functionality of the browser to prevent people from accessing the website without logging in.
Eliminate the Chance of Data Corruption:
The testers can use custom negative test cases to eliminate chances of data corruption by complementing user data and field type perfectly. They can make each control in a form or dialogue box access the right type of data – text, numeric and date. They can further enter data of wrong type into a control to check how the application behaves. For instance, they can assess the behaviour of the application accurately by entering text or numeric input in a date field.
Ensure the Correctness of Data:
In addition to making users to submit the right type of data, negative testing also helps testing professionals to ensure that the application only receives reasonable data. For instance, they can use negative test cases to ensure that no required field in form remains empty. Likewise, negative test cases can also be used for restrict the number of characters in user input, and restrict the input submitted by users with data bounds and limits.
On the whole, negative testing helps software QA testers to assess the quality of the software more accurately and enhance test coverage. When the test suite includes both negative and positive tests, the test results become more accurate and reliable. The testing professionals can further design both positive and negative test cases based on a number of common parameters like boundary value analysis and equivalent partitioning. But it is always important for them to pick the most appropriate negative test scenarios to generate more accurate test results.