For 100% error-free software, positive testing is not enough. A system is checked for unexpected conditions via negative testing!

The verification and validation of software application is known as software testing which involves checking if it works as expected. The existence of the positive and negative test means that every software application must be tested throughout the process of development in every way. It is to validate that the system does what it should do and does not do what it should not do, assisting the development team in solution and intervention so that the resultant product is as good as possible.

Depending on the software tests performed, it then focuses on a special attention point in the operation and all of them allow to analyze the “behavior” of the software at different times, allowing to act effectively on it in order to ensure maximum performance. Each of them brings “particular” answers to a stage or purpose of the project, all of which are important.

The relevance of understanding the difference between them is great in that the responsible team must be concerned with identifying the correct checking procedure for each level the software is in, in order to ensure that they are executed, evaluated and taken in to the stage in which he is or the purpose of his new version. Thus, results are obtained that are safer and also accurate in relation to performance, which also assists in continuous quality control and more detailed monitoring of progression phases.

There are two ways to encounter defects and improve software quality via testing; Positive and Negative Testing. Positive testing is the one that involves checking if the system input valid data to output valid results. Negative testing is done to check the response of the system when negative input is given. It comprises of deviation from the normal procedure to operate the system. Generally, positive testing is considered to be the first form of testing that takes place on the right path of application.

Negative-testing

Why do Negative Testing?

Software testing task requires much cost and time to decide ‘what to test’, ‘how to test’, and ‘how much to test’. You need to make a wise decision regarding negative testing of your software application. The two basic techniques for negative testing are boundary value and equivalence partitioning analysis that are applied to negative as well as positive tests.

Boundary value analysis involves testing the boundary of the values present in an application. Negative testing occurs when test execution input is done with the values outside the boundary. Equivalence partitioning analysis tests the application by division of data in equivalent partitions. Test cases are designed to address each of the given partitions. Negative testing takes place when you are using invalid values of the partitions. So, here you go with the five perspectives why negative testing is important for the QA of your software system.

Organization perspective

You need to perform negative testing if you wish to deliver a good quality product to your customer. It is your responsibility to check the software against failure, performing negative testing will allow you to confirm system success or failure. Although, it is imperative that no software is 100% error free, but negative testing enables you in prevention of software failure.

For instance, if you perform only positive testing on your e-commerce site someone can easily perform a security breach with an SQL injection, manipulating or erasing your data. Negative testing may help you find the loopholes in the system. Hacking is just one case that is covered by negative testing. But, it is as vital as many black hackers keep waiting to destroy your system.

In context of the public web and apps you must keep in mind that you don’t have much control over use and application procedure and to avoid any security breach negative testing is a must. Negative testing will cover all such cases to ensure the quality of your product. To validate the security services of an application, identify possible failures and weaknesses. Many projects use a black box approach for security testing, which allows experts, without software knowledge, to test the application for holes, faults, exploits and weaknesses.

Following the steps of the inherent complexity of our industry, the tests also suffer from an endless myriad of types, versions, evolutions and classes. But let’s focus on the most important and essential, according to each case and context.

Unit tests are automated tests that verify functionality in the component, class, method or level of ownership. The main objective of these tests is to isolate the small pieces of software from the remaining code and check its behavior. So, testing the units in isolation before integration with the components to see examine interfaces between the units.

Integration tests from a test perspective, the individual units are integrated together to form larger components. In its simplest form, two units that have already been tested are combined into an integrated component and the interface between them is tested. Integration tests or components identify problems that occur when the units are combined. The new errors that arise are probably related to the interface between the units instead of inside the units themselves; simplifying the task of finding and correcting defects.

Negative-testing

Client Perspective

Client’s only concern about negative testing is the cost, while they also seek 0% vulnerability in application. So, negative testing is a must to ensure security especially if your software application involves online stock, ecommerce etc. Such a product is sensitive and paying a high cost for testing is much bearable than paying for the failure. You may help the client in understanding the consequences of unattempt negative tests. However, final decision about whether to do or not do negative testing is made by the client.

Functional Reliability Perspective

Software application must be functional even in the most stressful situation. Basic reason why negative testing is beneficial for your software product is that is functions desirably even with the undesirable input. Small-scale tests, such as a single user running a web application or a database with only a handful of records, may not reveal problems that occur when the application is used in “real” conditions.

The stress test pushes the functional limits of a system. It is done by subjecting the system to extreme conditions, such as maximum data volumes or a large number of simultaneous users. They are also used to take the system to collapse or degradation, check its continued operation above its limit and, once freed of the load, evaluate its resilience capacity returning to its optimal state of operation.

Performance test determines the responsiveness, performance, reliability and / or scalability of a system under a given workload. In web applications, performance tests are often closely related to stress tests, the measurement of delay and the responsiveness under a heavy load. In other applications (desktop and mobile applications, for example), performance tests measure the speed and utilization of resources, such as disk space and memory.
If we store all the results of the performance tests during a period of time, we can know the health status of the application, being able to obtain trends and forecasts of operation; and optimizing each deployment according to the necessary performance in each case.

Reliability and stability of the system is examined by negative test cases. These are deigned to test system for unintended ways of using it. Embedded Single Quote is type of test case designed by software testing team to analyze issues with the system when users try storing single quote information. So, for screens to be tested for alphanumeric entries, input one or more singles quotes. Lower and upper bounds in the data field are tested using the Data Bound Test.

Tester need to test the field size for the number of characters that ensure its functional specifications. Test cases are required to see if the limit of character exceeds from the defined number. Thus, users may be prevented from exceeding the character limit, in contrary to make the mistake and then get an error message.

Positive-Testing

Error Validation Perspective

Human and machine interaction can never be 100% error free. Negative testing minimizes the likelihood of any kind of error caused by unpredictable human behavior. It prevents the system from unnecessary crashes, whereas you can easily anticipate the problem areas and integrate possible measures well before the user faces a problem. Negative testing may also allow you to validate the software for errors so that you may incorporate appropriate response for the users and provide them guidance in the right path. Numeric Bound Test is conducted to test the accuracy of the upper and lower bounds.

System is tested for Required Data Entry and Web Session Testing. All the fields in the software application that may involve entering data are tested. Since, some applications allow monitoring of user data in browser session, so it is tested by launching pages on the app that may not require users’ login.

Software Quality Perspective

Quality of the software application is usually assessed by its performance. Performance test cases are designed to identify the speed of screens and its overall performance. To assess the performance changes and improvement the test suite includes comparison of new and old version of statics. Thus, identify the potential issues in performance.

In an event of unexpected human behavior such as entering the incorrect data, if the system remains unhindered it determines the high quality of the software product. This type of software is a potential hit because it knows exactly how to respond to friendly even when the things go wrong. Thus, it is an obvious guess that negative testing has an effective contribution in the launch of software product.

Manual testing requires human interaction. The tester puts himself in the role of the user role that has to be validated and performs all those operations that he has defined in a test plan, or he looks for “tickling” the system to get there where no “user” has arrived. As you can see, both types of tests are complementary and important to guarantee quality software. Automation is fast and you can try many subtle variations in the data; you can also easily repeat the tests as the software evolves; and because it is executed by the system, fatigue and errors that sometimes accompany repetitive tasks are avoided.

In contrast, although manual tests generally take longer to execute (since they are performed by a person), they often require much less configuration time. It is a good choice for tests that only need to be run occasionally, or in cases where the cost / time of the automation configuration exceeds the benefits.

Software-Quality-Assurance

Conclusion
Functional, usability, exploratory, acceptance, infrastructure, etc. The universe of the tests is immense, being one of the branches of the wrong computer call, which requires a specific specialization. Negative testing allows you check the software for all the inconsistent data variables and unexpected behaviors.

Invision Solution makes your system more reliable by checking out the flaws and taking corrective measures on priority. System is fed with unexpected inputs and invalid data to break into the system and check its response. So, the final product that reaches you does not break out when it encounters an unexpected input.

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