Software testing is the process of evaluating a software system to detect differences between expected and actual behavior. It encompasses techniques for verifying that software meets its requirements (verification) and validates that it satisfies user needs (validation).

Origins and History

Software testing as a discipline evolved alongside software engineering. Glenford Myers’s 1979 book The Art of Software Testing established foundational concepts including the distinction between verification and validation, and defined testing as the process of executing a program with the intent of finding errors. The V-model, which maps testing levels to development phases, was formalized in the late 1970s and adopted in standards such as the German V-Modell (1992). The IEEE 829 standard (1998, revised 2008) standardized test documentation. The International Software Testing Qualifications Board (ISTQB), founded in 2002, established a global certification scheme that formalized testing terminology and practices. Test-driven development (TDD), popularized by Kent Beck as part of Extreme Programming (1999), reversed the traditional sequence by writing tests before code.

Testing Levels

Unit testing verifies individual components (functions, methods, classes) in isolation, typically written and maintained by developers. Integration testing verifies that components work correctly together, testing interfaces and data flow between modules. System testing verifies the complete integrated system against its requirements in an environment that resembles production. Acceptance testing validates that the system meets business requirements and is ready for delivery, often performed by end users or stakeholders (UAT).

Testing Techniques

Black-box testing designs test cases from specifications without knowledge of internal structure, using techniques like equivalence partitioning, boundary value analysis, and decision tables. White-box testing designs test cases based on internal code structure, using techniques like statement coverage, branch coverage, and path coverage. Regression testing re-executes existing tests after changes to ensure no existing functionality is broken. Exploratory testing relies on tester skill and intuition to simultaneously design and execute tests.

Sources

  1. Myers, G.J. (1979). The Art of Software Testing. Wiley.
  2. ISTQB (2018). “ISTQB Certified Tester Foundation Level Syllabus, Version 2018.” https://www.istqb.org
  3. Beck, K. (2002). Test Driven Development: By Example. Addison-Wesley.