Black box testing, also known as “behavioral testing,” is a software testing method where programmers test software functionalities without knowing its internal code structure, implementation details, and internal paths. It focuses entirely on application input and output functions based on software requirements and specifications.

So, what is black box testing for? Black box testing can evaluate operating systems (OSs), websites, databases, and even custom applications.

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Read More about Black Box Testing

Black box testing evaluates how a program behaves. The black box, in this case, is the testing environment. To evaluate a program, you give it inputs to see what it does by looking at the outputs.

black box testing

If, for example, you’re testing the site google[.]com, an input would be a search term like “black box testing.” And the output would be the list of pages where the term appears.

How Do You Perform Black Box Testing?

Black box testers follow various steps, namely:

  1. Examine the system requirements and specifications.
  2. Choose valid test inputs to check if the software processes them correctly.
  3. Choose some invalid inputs to verify if the software can detect them.
  4. Identify the expected outputs for all the inputs.
  5. Construct test cases for the inputs.
  6. Execute test cases.
  7. Compare the actual with the expected outputs.
  8. Defect if the defects have been fixed and retest. Do this step until there are no more bugs.

What Are the Types of Black Box Testing?

This software testing method comes in various kinds, such as:

  • Functional testing: This test evaluates the functional requirements of a system and is done by software testers.
  • Nonfunctional testing: This test doesn’t test specific functionality. Instead, it evaluates nonfunctional requirements, such as performance, scalability, and usability.
  • Regression testing: This test is done after code fixes, upgrades, or any other system maintenance to check if the new code affected the existing one.

Does Black Box Testing Have Pros and Cons?

Like any software test, this software testing method has advantages and disadvantages.


  • Testers don’t need technical knowledge, programming, or IT skills
  • Testers don’t need to learn about the system’s implementation details
  • Crowdsourced or outsourced testers can execute tests
  • Tests have a low chance of producing false positives
  • Tests are less complex since they simply model common user behaviors


  • Tests are hard to automate
  • Testing requires prioritization, as it’s typically infeasible to test all user paths
  • Hard to calculate test coverage
  • If tests fail, it can be hard to understand the root cause of an issue
  • Tests may be conducted at a low scale or in a non-production-like environment

How Does Black Box Testing Differ from White Box Testing?

White box testing means testing a software knowing detailed insider information on its source code, architecture, and configuration. It exposes security vulnerabilities, broken paths, or data flow issues that black box testing can’t test.

Most programmers combine black and white box testing to comprehensively inspect an application, thereby knowing it from “inside and out.”

How Does Black Box Testing Differ from Gray Box Testing?

While white box testing assumes the tester has complete knowledge of the application and black box testing assumes he does not know anything, gray box testing is a compromise. Testers have partial knowledge about the software and its internal workings.

Gray box testing is commonly used for penetration, end-to-end system, and integration testing.

Think of the three testing methods above this way.

Black Box TestingGray Box TestingWhite Box Testing
Tester has no knowledge about the software and its inner workingsTester has some knowledge about the software and its inner workingsTester has complete knowledge about the software and its inner workings
Performed by an independent testing team, usually testers contracted by a software developerPerformed by penetration, end-to-end system, and integration testers who may be part of the software company or outsidersPerformed by the actual developers of the software being tested

To ensure your software works as intended, it’s always best to perform all three methods—black, gray, and white box testing.

When asked what is black box testing and why it’s critical, you can say that it is an integral part of software development as it ensures the program works as designed.

Key Takeaways