White Box Testing vs Black Box Testing vs Gray Box Testing

White Box Testing

In white-box testing, the whole testing process is focused on the infrastructure of the software, including design, code, structure, and integration with other systems to evaluate and enhance the design and security of the software. White box testing allows us to have visibility of the source code of the application. Thus, it is also called Glass Box testing, Clear Box testing, Transparent Box testing, and Open Box testing. It is performed by developers or testers having good programming knowledge.

Advantages of White Box Testing

Below are some advantages of white-box testing: -

• It provides us with the visibility of the internal structure and code of the software to test and identify all possible bugs in the infrastructure of the application.
• It is more rigorous than other testing types as it covers and validates all paths and architecture of the application.
• It helps in quickly identifying hidden errors and faults in the code, which results in a fast debugging process.
• We can perform white box testing along with the SDLC phases once the code is developed.
• It can also be done before the completion of GUI as it is done on the internal structure of the system.
• It helps in identifying unused blocks and functions in the code, which results in dead code blocks.
• It also helps in increasing the efficiency and optimization of the program by removing the extra coding lines or new code.
• Test case preparation is very easy and quick in white box testing as test cases are prepared based on internal coding, which helps in identifying input data and their expected output.

Disadvantages of White Box Testing

Below are some disadvantages of white-box testing: -

• White box testing requires skilled and professional programmers or testers having good knowledge and understanding of programming languages, as white box testing is performed on the source code of the application.
• It is a very complex and expensive type of testing as it requires highly professional programmers or testers to perform it.
• While performing white box testing, testers can miss out on errors or dead code, which may lead to failures in future states.
• It is a time-consuming task in the case of large-scale programming projects.
• It is not recommended for projects where changes are frequently done in the code. In such cases, testers must prepare new test cases and need to test every scenario again.

Some white-box testing tools are JSUnit, CppUnit, NUnit, Veracode, CSUnit, PyUnit, Parasoft Jtest, HTMLUnit, and JUnit. Let us quickly brief each tool of white box testing.

1. JSUnit – It is a part of the JUnit framework and is used for writing repeatable tests in JavaScript language.
2. CppUnit – It is a module of the Unit testing framework and is mainly used for C and C++ programming languages.
3. NUnit – It is an open-source unit testing tool for Microsoft .net. In terms of functionality, it is very similar to the JUnit tool.
4. Veracode – It is a static analysis tool and platform which acts as a cloud-based solution for application security.
5. CSUnit – Like NUnit, it is also an open-source and free unit testing tool for Microsoft .Net. It is mainly developed for .Net compliant languages.
6. PyUnit - It is a unit testing framework mainly for Python language. It can easily create Unit tests and unit testing programs with python.
7. Parasoft Jtest – It is an integrated development testing tool developed for Java developers to enhance software quality.
8. JUnit – It is an open-source and free unit testing framework mainly used with java.

Black Box Testing

In black-box testing, there is no visibility of the internal structure and source code of the application. It keeps track of the behaviour and functionality of the software and ensures it should work as per the pre-defined requirements. It is usually performed by the testers because no programming knowledge is required to perform black-box testing. The main aim of black-box testing is to validate the functional and non-functional requirements and working of the application by providing a set of inputs and observing the outcome against it.

Advantages of Black Box Testing

Below are some advantages of black-box testing: -

• Black box testing doesn’t require any specific programming language to perform testing.
• Testing can be performed without having knowledge of the internal structure and architecture of the application.
• Testing activities are impartial and balanced as both testers and developers work separately and independent of each other.
• Testers can prepare test cases right after the specifications and requirements are defined.
• It is performed from the end user's perspective in terms of functionality, performance, and behaviour of the application.
• It is more suitable and compatible with large-scale projects.

Disadvantages of Black Box Testing

Below are some disadvantages of black-box testing: -

• As there is no visibility of the source code and architecture of the application, there may be an instance of missing some important and valid conditions for testing.
• If the specifications are unclear, then preparing test cases will be a very tricky task.
• Like white box testing, black box testing is also a time-consuming activity due to its multiple testing techniques.
• It is very challenging to identify all possible inputs for each scenario of the application. Hence, all the test scenarios and their inputs will not be completely tested using black-box testing.
• In some cases, there could be chances of using repetitive test cases.
• In black-box testing, the test cases result is often overrated.

Some black box testing tools are QTP, LoadRunner, and JMeter. Let us quickly brief each tool of black-box testing.

1. QTP – Quick Test Professional is an automation tool mainly used for performing functional testing.
2. LoadRunner – It is a licensed and commercial performance testing tool mainly used for measuring a system's performance and load.
3. JMeter - It is an open-source performance testing tool mainly used for measuring the performance and behaviour of the system under a certain load.

Gray Box Testing

In grey box testing, testers have partial knowledge and visibility of the system’s internal infrastructure. The primary purpose of grey box testing is to examine and enhance the system's quality by performing activities that cover white box and black box testing techniques. It includes the visibility of internal source code and algorithms as well as the system's requirements in terms of functional and non-functional requirements. Due to the partial visibility of the internal structure, grey box testing is also known as a semi-transparent box. Testers perform grey box testing based on their limited knowledge of internal code and the architecture of the system.

Advantages of Gray Box Testing

Below are some advantages of grey-box testing: -

• It plays an essential role in software testing as it consists of both white box and black box testing techniques.
• As grey box testing has partial visibility of code, therefore, highly skilled programmers or testers are not required.
• It provides developers with a good amount of time for fixing defects.
• It is more effective in performing Integration and Penetration testing of the system.
• Testing is done from the end user’s perspective instead of the developer’s or designers.
• It helps in enhancing the overall quality of the software.  

Disadvantages of Gray Box Testing

Below are some disadvantages of grey-box testing: -

• It is not suitable for performing algorithm testing.
• We have partial visibility of code, and we can't perform white box testing techniques completely.
• In grey box testing, some paths and codes will remain uncovered.
• It provides fewer test coverages than the white box and black box testing.
• It is an expensive and time-consuming testing process as it takes a lot of time to cover every path to perform testing.

Some black box testing tools are QTP, Postman, Burp Suite, JUnit, NUnit, DBUnit, and JMeter. Let us quickly brief each tool of grey-box testing. Most grey box testing tools are the same as white box and black box testing.

1. QTP – Quick Test Professional is an automation tool mainly used for performing functional testing.
2. Postman – It is basically an API platform for creating and using APIs and is mainly used for API testing.
3. Burp Suite – It is mainly used for Penetration testing. It is a set of tools used for web-based application testing.
4. JUnit – It is an open-source and free unit testing framework mainly used with java.
5. NUnit – It is an open-source unit testing tool for Microsoft .net. In terms of functionality, it is very similar to the JUnit tool.
6. DBUnit – It is a JUnit extension mainly used for database-driven projects and testing.
7. JMeter - It is an open-source performance testing tool mainly used for measuring the performance and behaviour of the system under a certain load.

White Box Testing vs Black Box Testing vs Gray Box Testing

Below are the key differences between white-box testing, black-box testing, and grey-box testing: -

White Box Testing	Black Box Testing	Grey Box Testing
White box testing is a type of manual testing that focuses on testing an application's code. Each line of code is examined and validated before being it to the testing team.	Black box testing is a type of manual testing that focuses on functional and non-functional behaviour. Testing is done to examine the developed software against the requirements specified by the clients.	It is a type of manual testing which is a mixture of both white-box and black-box testing. The name itself suggests that it is a product of white and black.
It requires a good understanding and knowledge of the internal structure and coding of the application.	It doesn’t require the knowledge of internal structure and coding of the application.	It requires partial knowledge of the internal structure and coding of the application.
It is usually performed by developers and testers.	It is usually performed by developers, testers, and end-users.	It is also performed by the developers, testers, and end-users (User-Acceptance Testing).
The whole testing process is focused on the infrastructure of the software, including design, code, structure, and integration with other systems to evaluate and enhance the design and security of the software.	Testing is performed based on the specifications defined by the clients and users. It is mainly done for validating the functional requirements and working of the application.	It is performed to examine and enhance the system's quality by performing activities that cover both white box and black box testing techniques.
The white box testing mainly covers three testing techniques which are Statement Coverage, Decision/Branch Coverage, and Condition Coverage.	The black box testing mainly covers six testing techniques which are Equivalence Class Partitioning, Boundary Value Analysis, Decision Table, State Transitioning, Use Case Testing, and Cause-Effective Graph/ Graph-Based Technique.	The grey box testing mainly covers four testing techniques which are Matrix Testing, Regression Testing, Orthogonal Array Testing, and Pattern Testing.
It is also known as Glass box testing, Clear box testing, Transparent Box testing, Structural testing, Code-based testing, and Open box testing.	It is also known as Close box testing, functional testing, Data-driven testing, Specification-based testing, and Behavioral testing.	It is also known as a Semi-Transparent box and Translucent testing.
White box testing has a high level of granularity.	Black box testing has a low level of granularity.	Grey box testing has a medium level of granularity.
White box testing is compatible and most suitable for algorithm testing.	Black box testing is not suitable for algorithm testing.	Similarly, grey box testing is not suitable for algorithm testing.
It is the most exhaustive testing of all three types.	It is less exhaustive testing as compared to white box testing.	It is partially exhaustive as compared to the other two types.
It is a lengthy process and consumes more time than black-box testing.	It consumes less time compared to white box testing and time consumption depends on the availability of functional requirements.	It consumes less time in comparison to the other two types of testing.