Negative Testing – What It is And How To Do It?

Negative testing is done to test how the software performs when it gets incorrect or invalid information. In contrast, positive testing aims to ensure that the software produces the right functions when it gets valid input.

What Is Negative Testing?

To deliver a quality software product to a client, you require to make sure that you have examined all the possible input parameters. The software that you deliver should function as expected.

This indicates that the software should perform the correct functions when you execute an action or input information. It also requires giving the right response when someone enters incorrect information. For this purpose, it is important to consider doing negative testing.

Negative testing takes a different strategy than positive testing. Negative testing helps to assure that you consider all scenarios. It is highly doubtful that the software will only ever get valid input. This is because it is very simple to make a mistake, mistype something, or fill in the incorrect field due to human error.

It is also crucial to test what happens when someone inputs incorrect data. This is important for security purposes and to stop any malicious and costly data breaches. In other words, while it is important to make sure that a software program runs efficiently, you also require to think about all of the parameters and think about what could go wrong.

Thus, negative testing attempts to test out all the various data inputs that could be entered inaccurately. Developers then use this process to design enough responses to this invalid information. These responses could incorporate error messages, failure to submit any data, and/ or continue to the next stage of the data entry process.

Examples Of Negative Testing

To explain what negative testing is, we can use the example of entering a necessary name value into an online entry field.

If you enter wrong data, like a string of numbers instead of letters, the program requires you to give an appropriate response. This would be to alert the user in a specific way. For example, it might display an alert message in red text and not continue to the next function.

Another example is testing incorrect data input into a field that needs a specific form of data entry. This could involve placing a non-existent date into a data entry field, or the age 200 into an entry form.

Thus, negative testing attempts to think about what could be entered inaccurately. This helps to assure that the software can respond properly to any invalid information.

As we touched on above, it is essential to have an understanding of what parameters can be estimated negative before you can carry out negative testing.

To make things easier, negative testing parameters can incorporate a range of negative inputs grouped. This makes testing quicker and more effective. Looking back to the name entry example, inaccurate data could, therefore, incorporate data like numbers, an empty field, special characters, and too many letters.

Negative Test Case Parameters

When developing a simple software application, setting the range of incorrect inputs might be more straightforward. However, with a large-scale application, it can be simpler to use the following tools to discover negative testing parameters.

1. Boundary Value Analysis

In the case of boundary value analysis, you consider that data is wrong if it falls outside of a particular boundary range. Thus, you can utilize this data for negative testing.

As discussed above, when entering data about age, any number beyond a reasonable life expectancy may be a negative input. So, any number greater than 100 is regarded beyond the boundary and is, therefore, an invalid input. You can then utilize this range of inputs when producing your negative testing strategy.

2. Equivalence Partitioning

Equivalence partitioning also distributes valid and invalid data into separate partitions according to a variety of values.

Following on from the example in the earlier point, on a linear chart, all of the numbers from 1 – 100 would be partitioned into actual data classes. You would then think of all numbers above 100 as invalid data classes.

Essentially, both of these tools include mapping out the appropriate parameters along positive and negative axes. This enables you to cover a wider scope of possibilities when developing your testing approach.

How To Do Negative Testing?

All of the above points present a fair indication of how to start considering writing negative test cases. However, it is really significant to take the time to sit down and think about all the possible situations that could influence your application negatively before doing so.

Of course, negative testing also requires to factor in budget considerations. So, while you could examine infinite possibilities, you do require to prioritize certain testing parameters upfront. This will assure that you don’t waste any time or money.

Thus, designing a sufficient test case involves testing any kind of data input that could possibly cause your application to crash. This is precisely what you don’t want to happen when a customer uses your finished product. You’ll also want to cover all of the potential security pitfalls that could happen when setting the priorities of your test case.

It is also important to think about all of the unexpected data that one could enter into the program. These incorporate simple mistakes that might have been neglected, but which could lead to frustration for users.

Conclusion 

After reading this article, you now understand the difference between positive and negative testing. You should also have a good concept of what negative testing is. We have also given some examples of negative testing, some tools to set parameters, and how to think about creating your first negative test case.

Need some guidance in performing negative testing? Choose to team up with a QA services provider like TestUnity. Our team of testing experts specializes in QA testing and have years of experience implementing tests with testing software. Partner with our QA engineers who can help your team in adopting negative testing best practices. Get in touch with a TestUnity expert today.

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