White Box Testing and Black Box Testing

Testing software begins earlier in the systems development life cycle, even though many of the actual testing activities are carried out during implementation. During analysis, you develop an overall teat plan. During design, you develop a unit test plan, an integration test plan, and a system test plan. During implementation, these various plans and put into effect, and the actual testing is performed. Testing is the process of evaluating software or its component(s) with the intent to find whether it satisfies the specified requirements or not.

White Box Testing

White Box Testing is a software testing technique in which internal structure, design, and coding of software are tested to verify the flow of input-output and to improve the design, usability, and security. ... The term "WhiteBox" was used because of the see-through box concept. White-box testing (also known as clear box testing, glass box testing, transparent box testing, and structural testing) is a method of software testing that tests internal structures or workings of an application, as opposed to its functionality (i.e. black-box testing). 

Normally white box testing done by testers and developers. Advantages and disadvantages of White Box testing are as:

Advantages:

1. As the tester has knowledge of the source code, it becomes very easy to find out which type of data can help in testing the application effectively.
2. It helps in optimizing the code.
3. Extra lines of code can be removed which can bring in hidden defects.
4. Due to the tester's knowledge about the code, maximum coverage is attained during test scenario writing.

Disadvantages:

1. Due to the fact that a skilled tester is needed to perform white-box testing, the costs are increased.
2. Sometimes it is impossible to look into every nook and corner to find out hidden errors that may create problems, as many paths will go untested.
3. It is difficult to maintain white-box testing, as it requires specialized tools like code analyzers and debugging tools.

Black Box Testing

Black Box Testing is a software testing method in which the internal structure/ design/ implementation of the item being tested is not known to the tester. White Box Testing is a software testing method in which the internal structure/ design/ implementation of the item being tested is known to the tester. Black box testing can be applied to three main types of tests: functional, non-functional, and regression testing. Black Box Testing, also known as Behavioral Testing, is a software testing method in which the internal structure/design/implementation of the item being tested is not known to the tester. These tests can be functional or non-functional, though usually functional.  

Black box testing performed by end-users and also by testers and developers. It is exhaustive and the least time-consuming. For example an operating system like Windows, a website like Google, a database like Oracle or even your own custom application. Under Black Box Testing, you can test these applications by just focusing on the inputs and outputs without knowing their internal code implementation.

Black-Box Testing

Advantages	Disadvantages
Well suited and efficient for large code segments.	Limited coverage, since only a selected number of test scenarios is actually performed.
Code access is not required.	Inefficient testing, due to the fact that the tester only has limited knowledge about an application.

References:

1. Brijendra Singh, “ Systems Analysis and Design,” New Age International Publisheer’s, New Delhi Year: 2016
2. Brijendra Singh, Shikha Gautam, “ Systems and Software Process”, Narosa Publication House, New Delhi Year : 2020.