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White Box vs. Black Box: A Basic Overview of Software Testing

Black box appearing above white box to signify white and black box testing practices

Software testing is a necessary component of the development process. Simply put, testing ensures that software does what it is supposed to do, free of errors or bugs that detract from user experience. Without detailed testing and quality assurance processes, software released onto the market might function poorly or prove harmful, frustrating customers while damaging the producer’s reputation.

While software testing can be time intensive, it is a worthwhile investment. When incorporated into projects from the beginning, well-designed testing procedures save time by ensuring that bugs are discovered early, making extensive, last minute code repair less likely.

Software testing can be broken down into two main categories: white box and black box testing. White box testing (sometimes called “clear box” or “glass box” testing) requires the tester to know and understand how the software works – they are able to “see inside” the program. Black box testing (sometimes called “behavioral testing”) requires the tester to understand what the program is supposed to do, but not how it works – they are unable to “see inside” the program. A white box tester is usually a developer, as some degree of programming experience is required. By contrast, it can be useful for black box testers to lack such technical perspective, as their experience of the software should closely resemble that of an end user.

What are the differences between white box and black box testing?

White box testing usually begins early in the development cycle. It is conducted at lower levels, and includes unit and integration testing. Black box testing is mainly higher level, as in system and acceptance testing, so implementation comes later in the development cycle.

What are the benefits and drawbacks of white box testing?

Benefits of white box testing

  • Can be done by development team
  • Does not require a completed GUI
  • Highly systematic / easy to reproduce
  • Thorough – can test every possible path
  • Can uncover errors early in the development process

Drawbacks of white box testing

  • Time required of developers
  • Code updates can invalidate test cases
  • Hard to separate the program and the testing environment

What are the benefits and drawbacks of black box testing?

Benefits of black box testing

  • Testers need not be highly technical
  • Simulates end user experience
  • Easy to create test cases
  • Value of external/non-developer perspectives
  • Can often be automated

Drawbacks of black box testing

  • Usually does not capture all scenarios / software paths
  • Testing outcomes can be difficult to document and/or reproduce
  • Tests can be redundant and time intensive

Which is “better” – white or black box testing?

Neither – they are both necessary and complementary. Early white box testing assures code functionality and makes later, higher level testing less time intensive. Thorough black box testing enhances end user experience. Systematic testing procedures, incorporating a variety of strategies and perspectives, result in a solid final product and a successful release.

Chris Toler