Software testing methods: Black box testing and white box testing

When it comes to software testing there are two distinct methods of carrying it out, namely black box testing and white box testing. Both these approaches have their own merits, demerits, and attributes that come with their own challenges during the process. Although there is also grey box testing it is not as popular or widely used as the aforementioned ones.

Black box testing:

Black box testing can be executed without the prerequisite knowledge of the detailed workings of the subject being tested. This particular approach to testing does not require the person doing the testing to be aware of the system architecture or even the source code that is used. The point of focus of this approach is interaction with the user interface as well as plugging in inputs and analyzing the corresponding outputs. However, black box testing also has two distinct subdivisions called functional testing and non-functional testing.

Some advantages of black box testing are as follows:

They work well and efficiently when the subject that is being tested has multiple segments of code

Access to the source code is irrelevant and not needed

A clear distinction between the user’s frame of reference and the developer’s frame of reference.

Since no prerequisite knowledge about the inner workings is required, it is possible to  employ a larger number of moderately skilled people for the execution of this project

Some disadvantages of black box testing are as follows:

Only a limited number of tests can be executed so this means the scope of the test is limited in nature.

Given that the tester himself has a limited understanding, the entire process does run the risk of efficiency.

Due to the tester not being able to isolate segments of the code and testing them it leads to a sort of blind coverage.

Despite everything the black box tests are considered hard to design

Some things that are tested during a black box testing are as follows:

Unit testing

Smoke testing

User Acceptance

Integration testing

Regression testing

Globalization

Localization

Interoperability

Some types of black box testing are as follows:

Functional testing (as the name suggests, related to the functional requirements of a system)

Nonfunctional testing (as the name suggests, related to non-functional elements such as usability, scalability, and performance)

Regression testing (done postcode fixing and upgrading with the aim of maintenance)

White box testing

White box testing, alternatively known as glass testing or open box testing,  unlike its counterpart is hinged on a whole lot of details, internal logic, structure, as well as the code of the software. This kind of testing demands that the tester executing it is well aware, informed and has a satisfactory understanding of the inner workings of the subject.

The tester is required to analyze the individual segments of code and arrive at concrete conclusions based on observations. (which part of the code is working well and which part of the code is erroneous). This kind of testing is usually employed at the unit level of things

Some advantages of white box testing are as follows:

Since the tester performing the execution is well versed with the subject at hand as well as the source code it becomes very easy to isolate and identify issues and other points of improvement.

This method more often than not leads to the optimization of the code

Since the tester has access to the source code, unwanted and irrelevant segments can be discarded

Given that the tester performing the execution is seasoned, the coverage of this kind of testing can be considered significantly high as well as thorough.

Some disadvantages of white box testing are as follows:

The disadvantages of white box testing are as follows:

The labor cost involved in this process is relatively and significantly higher.

Sometimes due to the sheer size of the code, it gets arduous and strenuous to go through every segment of code, which also leads the entire process to prove extremely time-consuming

White box testing requires extremely specific tools and people with extremely specific abilities (code analyzers, debugging tools, etc), this makes the maintenance of the process a bit of a challenge.

Some types of white box testing are as follows:

Statement coverage (making sure each line and segment of the code has been executed and tested).Branch coverage (making sure that everywhere there is a yes or no decision in the source code it is executed and checked). Path coverage (making sure that every path that can be taken in the source code is evaluated and tested). A good software test is one that includes both black box testing as well as white box testing, considering it is obvious that both the methods together is what leads to efficient testing with optimum results.