Know-how of black box testing

What is black box testing?

Black box testing is a technique wherein the functionality of the application is tested upon. The tester here does not look into the internal coding structure of the program or software. Neither does he look at the implementation details nor does he need to possess knowledge on the internal path-ways of the software program. As far as black box testing is concerned, the predetermined input values are tested against the estimated output values. This is done without looking at the internal structure of the software.

You can thus conclude saying that black box testing merely suffices Application under Test or AUT.

Input→ Black box testing → Output

Classic examples of black box testing on a daily basis

You may download the latest version of Windows 10. You run the program to check if Windows 10 works properly or not. Else it can be a database like Oracle. Else your very own custom application.

You can even be running a play app you downloaded via a playstore on your mobile phone. Without any technical background or know-how, you perform black box testing on a day to day basis. You just ensure if the application you have downloaded works fine or is compatible to your PC requirements.

Criteria needed to perform or access black box testing

Under a black box application, you just enter the inputs as specified by the software. You look for a desired output as recommended by the very same program. You do not need any coding implementation whatsoever. When the left hand side matches the right hand side, you can be rest assured that the software works fine.

Series of steps involved while performing a black box testing

For performing a black box testing in a technically viable manner, you will have to implement the series of steps mentioned below. These are:

• The black box tester will have to examine the specifications of the system. Here, the independent requirements of the system compatibility is also looked into. Say for downloading a particular software, you must install certain plugins or cookies. This will also be looked into by the tester.
• The input values are then punched into the system, server or via any other service client. You check for positive test cases. If the SUT processes them with a negative test case, then the tester will have to look into the same. There might be a bug or a potential dysfunctionality involved.
• The tester now evaluates the outputs.
• The selected inputs and the derived outputs are now measured against the expected outputs the software is supposed to deliver.
• Defects or bugs are detected at this stage.
• If the software contains too many bugs, then it is sent across to the developing team. The software then has to be re-wired or re-configured.

Types of black box testing

Although there are many types of black box testing techniques known to the market, these are the most prominent ones. Taking you through a glimpse into each one of them:

Functional testing

This is a type of black-box testing that accesses the functional requirements of the system or software. Usually, functional testing is done by software testers.

Non-functional testing

This is a type of black box testing that does not look into the functional requirements of the system. Rather the tester looks into the non-functional aspects of the software. These include performance, usability and scalability.

Regression testing

Regression testing is a technique that is done post code fixes, system upgrades, maintenance and so on. This is a black box testing that is done to check if the new coding does not alter the existing platform.

Tools required for black box testing

Black box testers can make use of the following tools to smoothen testing processes. These are

1. QTP
2. Selenium
3. LoadRunner and
4. JMeter

Testing strategies for black box testing 

These are some of the prominently used test strategies used in black box testing. Helping you glance into each one of them:

Equivalence class testing

This is a strategy that minimizes the number of possible test cases to an optimum level. This way, the software testing team maintains a reasonable test coverage indeed.

Boundary value testing

Boundary value testing is a strategy that checks the input values of the system across boundaries. The evaluator assesses the values of inputs across a certain range or specified boundaries. This is a pivotal technique that is used by testers to reduce the number of test cases. You also understand whether the system takes in input-values belonging to that particular range or boundary.

Decision table testing

This is a decision making strategy wherein the possible cause and effect analysis is done across a matrix table. You configure a unique combination in each column.

Conclusion

You have a conceptual understanding on what black box testing is all about. The online guide also covers the strategic steps that are involved to perform black box testing. You have a list of tools involved. You also have a brief overview on testing strategies that support a series of black-boxing techniques. Your overall know-how guide of black box testing therefore comes to an end!

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