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Understanding White Box Testing and Black Box Testing Approaches

October 19, 2017

Understanding White Box Testing and Black Box Testing Approaches

Software testing is the process of evaluating software functionality and quality by detecting bugs and later removing them with the help of QA team or an efficient testing tool.

Testing validates a software by checking whether it is meeting business and technical requirements with guided design.

Software Testing is required for the following reasons:

  • Cost Effective
  • Security
  • Product Quality
  • Customer Satisfaction

There are several different testing techniques; Black Box and White Box testing are two such approaches commonly used by testers.

Black Box Testing

Testing is broadly based on software requirements and specifications. Black Box Testing is a technique in which tester is unaware about the internal structure or code of the software.

The focus is on inputs and outputs ignoring the internal knowledge of the code. Using black box testing, one can test operating systems like Windows, websites like Google and even our own customized applications, as the core knowledge about these operating systems are not required.

How Black Box Testing Works?

Black box testing can broadly be summarized into the following steps.

  1. The first step is to thoroughly examine the requirements and specifications of the system.
  2. The tester explores the system’s UI and functionality to understand how the processes on the system are expected to work.
  3. On later stage, the tester checks efficiency of the software by determining expected outputs with their corresponding inputs.
  4. Finally, the developer fixes the bug detected and the output undergoes retesting.

Black Box Testing Techniques

There are three techniques usually employed by organizations and testers in case of Black Box Testing.

Equivalent Class Testing: It is used to reduce the number of possible test cases to an ideal level to maintain a reasonable test coverage.

Boundary Value Testing: It determines whether certain range of values are accepted by the software or not. This helps in reducing number of test cases.

Decision Table Testing: A decision table puts conditions and their outcomes in a matrix. There is a unique combination in every segment.


  • Suitable for large code segments
  • Increased Efficiency
  • Prior knowledge of code is not required

Black box testing is all about enhancing the user experience even if they are from a non-technical background. On the other hand, for technical support and precise coding, White box testing is an excellent approach for organizations to employ. Let's understand the nitty gritty of what goes behind White Box Testing.

Increase testing efficiency and productivity with these testing approaches to gain more visibility

White Box Testing

White Box Testing is also known as open, transparent or glass box testing. In white box testing, the tester has prior knowledge of the code and accordingly prepares the test case.

The tester has the knowledge of the internals of a system and knows how the system is implemented. The tester uses this knowledge to develop test cases that will examine the control flow, information flow, data flow, exception and error handling as well as coding practices of the system.

How does White Box Testing work?

Here's how White Box Testing works ...

  1. The first step for the tester is to understand the source code.
  2. White Box testing then involves testing of internal functions of the application, so knowledge of source code is crucial.
  3. The tester should be aware of the secure coding practices as security is the most important factor in testing.
  4. Tester can then write code for testing the application or can prepare certain test cases with suitable inputs.

White Box Testing Techniques

Code Coverage Analysis: It eliminates gaps in test case suite by identifying the program which cannot be examined by test cases. In addition, you can create test cases for untested part of the program which improves the quality of the software.

Statement Coverage: This technique checks every statement of the code at least once during the test cycle.

Branch Coverage: This technique tests every possible path in the code like If-else loops and other conditional loops of the software.


  • It optimizes the code as it tests every statement of the code.
  • Automated testing is supported.
  • Tests and test scripts can be reused.
  • Testing is supported at early development stages.

Software testing is the most important part for maintaining the quality of the software. Manual and automated testing both are required to test the software thoroughly.

Taking up the black box and white box testing using an automated testing tool such as TestingWhiz is highly recommended. Automated testing allows the tester to focus more on the high priority issues plaguing on the deployment of the software instead of the repetitive mundane tasks that testing needs. This helps save time, increase productivity and efficiency of the testers along with boosting employee morale. Moreover, testers from all backgrounds can use it seamlessly.


TestingWhiz is committed to provide an innovative and automated software testing solution to the global enterprises and software companies for their web, mobile and cloud applications.


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