What is Black Box Testing

Black Box Testing

Black Box Testing is a software testing method in which the functionalities of software applications are tested without knowing the internal code structure, implementation details, and internal paths. Black Box Testing mainly focuses on the input and output of software applications and is entirely based on software requirements and specifications. It is also known as Behavioral Testing.

Black Box Testing Techniques

Following are the prominent Test Strategies among the many used in Black box Testing
  • Equivalence Class Testing: It minimizes the number of possible test cases to an optimum level while maintaining reasonable test coverage.
  • Boundary Value Testing: Boundary Value Testing is focused on the values at boundaries. This technique determines whether a specific range of values is acceptable to the system. It is beneficial in reducing the number of test cases. It is most suitable for systems where an input is within specific ranges.
  • Decision Table Testing: A decision table puts causes and their effects in a matrix. There is a unique combination in each column.

Types of Black Box Testing

There are many types of Black Box Testing, but the following are the prominent ones –
  • Functional testing – This black box testing type is related to the applicable requirements of a system; software testers do it.
  • Non-functional testing – This type of black box testing is not related to testing specific functionality but non-functional requirements such as performance, scalability, and usability.
  • Regression testing is done after code fixes, upgrades, or any other system maintenance to check the new code has not affected the existing code.

How to do Black Box Testing in Software Engineering

Here are the generic steps to carry out any Black Box Testing.
  • Initially, the requirements and specifications of the system are examined.
  • The tester chooses valid inputs (favorable test scenario) to check whether SUT processes them correctly. Also, some invalid inputs (adverse test scenarios) are selected to verify that the SUT can detect them.
  • The tester determines the expected outputs for all those inputs.
  • The software tester constructs test cases with the selected inputs.
  • The test cases are executed.
  • The software tester compares the actual outputs with the expected outputs.
  • Defects, if any, are fixed and re-tested.

Tools used for Black Box Testing:

Tools used for Black box testing largely depend on the type of black box testing you are doing.
  • For Functional/ Regression Tests, you can use – QTP and Selenium.
  • For Non-Functional Tests, you can use – LoadRunner Jmeter.