All about Black Box Testing

What is black box testing?

It is a type of testing used to check the functionality of the Application Under Test (AUT). We carry out this testing without viewing the internal code structure, implementation information, and details of the internal paths of the software – Black Box Testing

When it comes to BlackBox testing we only concern ourselves with the requirements and specifications of the software. Our primary focus remains on the inputs and outputs of the software system.

Not much emphasis is put on the internal knowledge of the software program. This type of testing keeps the overall functionality of the software in mind.

As seen in the above picture the BlackBox can be any software system that you want to do testing on. Be it an operating system, website, database, or even an application you develop yourself you can run this type of testing.

To test these types of applications for their functionality all you need to do is focus on the input and output without worrying too much about the implementation of internal code.

In case of an unfavorable output coming in as a response to an input, it counts as a bug. This bug is then sent for fixing after in-depth analysis. The test cases have different input combinations. They are made based on software specifications such as functionality, usability, and performance.

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The fact that we are unaware of the internalities of software gives rise to its name of BlackBox. We use this type of testing to reveal errors in the following domains:

• Faulty or missing functions
• Errors in the interface
• Bugs in data structures or external database access
• Errors in behavior or performance
• Errors of Initialization and termination

How is it done?

There are a few basic steps to carry out BlackBox testing. The first step is to check the specifications and requirements of the system. There are two types of test scenarios, positive and negative.

In a positive test scenario, we see if the processing of valid inputs by SUT is correct or not. While in a negative test scenario we check if SUT can detect some valid inputs.

So the tester determines a set of outputs for all those inputs. After constructing the test cases with pre-chosen outputs the testing is done on the software.

Once the comparison between expected and real outputs is over, then we fix any apparent bugs and flaws and then send the software for re-testing.

Types of BlackBox testing?

Various types of Black Box Testing exist but these are the few prominent ones:

• Functional testing – The black box functional testing is done to check the functionality of a system.
• Non-functional testing – This testing is not about the functionality of the software but more about performance, scalability, and, usability.
• Regression testing – After all upgrades and code fixing is complete we then carry out regression testing to check if updates have affected the existing code.

Techniques

Equivalence class testing: It lowers the number of test cases to a favorable level, reasonable to carry out efficient testing.

Boundary value testing: We use this testing to check whether a certain range of values are compatible with the system or not. It helps to narrow down the number of test cases. So it is essential in systems that certain ranges for their input.

Decision table testing: It is testing done for different input combinations. So we check the systems corresponding response to various input combinations. We record this type of testing in a tabular format.

The good and the bad

Advantages:

• The tester does not need to have in-depth knowledge of programming and implementation. It can be done by someone without technical knowledge
• There is no codependency between the tester and the developer
• Allows testing of quality by comparing expected and real outputs
• Testing from the user’s point of view allows it to be more user-friendly
• Testing after developing team releases the software so there is no expectation of testing from developing team
• Very effective for complex software systems
• Working on the tests of designs can begin as soon as specifications are complete

Disadvantages:

• Absence of programming knowledge can result in missing out of some unknown conditions
• This type of testing results in the restriction of the number of possible inputs and many program path do not undergo testing
• It does not allow enough time for the testers to identify all possible inputs to formulate test cases.
• Repetition of the test can take place if both tester and developer carry out the same tests
• If the application is too complex it is hard to achieve 100% test coverage

Conclusion

The digital world sees new applications emerging every now and then. This makes it very important to carry out software testing. So Black box testing is very efficient and many software developers affirm it.

This process has high recommendations for most projects. The end goal of this type of testing is to remove all errors and enhancing the quality of the software.