Negative Testing

What is ​Negative Testing?

• It is obvious that testing the software with only positive scenarios ensures that the software is working as expected but does not guarantee how it would work for unexpected situations. As a tester, the primary motive of testing is to find as many defects as possible and ensure that the application should work correctly even for odd situations. For this purpose, negative testing came into the picture which covers all the scenarios that need to be tested for the unexpected human behavior and invalid input from a user.
• It is generally known as error path testing or failure testing. It is a type of software testing that is performed in order to ensure that the software application should not break and gracefully handles the situations of unexpected scenarios like invalid user input, loss of network connectivity, missing required fields, etc.
• When the application is handed over to the end-users, it is no so that they will only perform the positive test scenarios, the human mind tries to play tricks and performs several illogical and inappropriate tasks either to test the application or for some personal unethical means.
• So it is very important to test the application with each permutation and combination of data in order to check how the application responds. For example, writing the alphabet or special characters in a phone number field, submitting a form without filling mandatory details, etc. such situations should be gracefully handled with the warning message. It is done with the intent of checking the stability of a software application.

Why do we need Negative Testing?

There are several reasons for performing Negative Testing. Some of them are mentioned below:

1. Though it is not possible to provide 100% fault-free software to the end-users, performing it and covering maximum negative scenarios can ensure that the application can handle unexpected situations.
2. There are a lot of hackers in the market seeking an opportunity to hack an application and misuse the customer’s private data, to avoid such situations of security breaches, negative testing is very important.
3. Unfolding the loopholes in an application by performing it in order to prevent unexpected behavior.
4. Ensure the stability of application for the out of the limit, uncommon and bad data.
5. In order to provide a vulnerable and robust application to the client, negative testing is a must.

How Negative Testing is Performed?

As it demands both the time and cost. A separate team of testers is required in order to perform enhanced negative testing.

• Negative test cases specifying multiple test scenarios need to be created for every functionality.
• Negative scenarios with all possible invalid data need to be tested according to the priority of negative data.

There are two techniques commonly used by testers for the negative testing which are mentioned below:

1. Boundary Value Analysis

​In Boundary Value Analysis, negative test cases are designed for the values outside the boundary limits in order to verify how the system works for them. For example, if a text field in a form accepts the data from 5-30 characters, so the boundary limits would be 5 and 30 and hence these values would be tested.

2. Equivalence Partitioning

In Equivalence Partitioning, input values are divided into different partitions of equivalent data and only a few values of each partition are tested in order the verify the whole partition. If the data passed, then the whole partition considers being pass else failed. For the above example, for the text field accepting data between 5-30, partitions would be 0-5, 5-30, 30-100, for the negative testing, partitions of 0-5 and 30-100 would be tested.

Advantages and Disadvantages of Negative Testing

Following are the advantage and disadvantage of negative testing are as follows:

Advantages

• To ensure vulnerable and quality software, negative testing is a must.
• To prevent the software application from cybercrime and unethical hacks, security testing for negative scenarios plays an important role.
• It gives them confidence that the application is tested against all negative scenarios and hence more reliable.
• It ensures that all the errors or the bad situations are handled gracefully by the software application.

Disadvantages

• Sometimes, in some applications, it becomes a waste of time. Intense it is covering all the negative scenarios with multiple negative test data is not always required. Testers at times get so much involved in it that the rigorous positive testing (basic functioning of an application) is left undone.
• For the detailed, a separate team of testers is required in the project which can cause high project budget issues.
• The release cycle of the application is sometimes delayed.
• Highly experienced people are required for negative testing.

Tools used for Negative Testing

Though there are no specific tools available in the market. Test cases to cover all the negative scenarios can be performed either manually or through automation scripts. The most important thing while performing it is the maximum number of permutations of the test data that can be tested for a test case. Manually testing the test case with each test data can be a little boring and time consuming but this task can be eased by automation testing. Automation scripts can be created through simple Automation tools available in the market like Selenium, TestComplete, Appium, Cucumber, etc. Automation scripts can be helpful in order to cover as all the test data can be stored in a single file for every test case and the script can be executed again and again for each test data.

Conclusion

Negative testing is not included and is never a part of positive testing, as the positive testing ensures the system is working as per the requirements and as mentioned in the documents (SRS) whereas it indicates the robustness, vulnerability and high-quality standard of the software. Negative testing is as important as positive testing as both have different intent to test the software. The more the software goes through testing, the less are the chances of risk in the market make the application more stable and reliable.

Recommended Articles

This is a guide to Negative Testing. Here we discuss the introduction to Negative Testing,  why do we need this testing along with the advantages and disadvantages. You may also look at the following articles to learn more –

• Unit Testing
• Static Testing
• System Integration Testing
• Black Box Testing