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What is Testability

Testability refers to how easily and effectively a system, software product, or component can be tested to uncover defects and verify that it meets its requirements (ISO 25010). It indicates the effort required to design, run, and evaluate tests. Systems with high testability enable faster, more reliable testing and are generally easier to maintain, resulting in higher overall product quality.

1. Testability in the ISO/IEC 25010 Standard​

Testability is explicitly defined in the ISO/IEC 25010 standard, part of the SQuaRE (System and Software Quality Requirements and Evaluation) series.

Within this model, Testability is classified as a subcharacteristic of the quality characteristic Maintainability.

This placement highlights that the ease with which a system can be tested directly supports maintainability. When testing is straightforward and reliable, diagnosing issues, verifying fixes, and validating changes all become more efficient.

Testability sits alongside other subcharacteristics under Maintainability, including:

  • Modularity: The degree to which a system is composed of discrete components.

  • Reusability: The degree to which a component can be used in more than one system.

  • Analyzability: The ease with which the impact of changes can be assessed, and diagnosis of deficiencies can be performed.

  • Modifiability: The degree to which a product can be effectively and efficiently modified.

These characteristics collectively support the long-term maintainability and evolvability of software and systems, with Testability playing a foundational role.

2. Testability in the Menditect Testability Framework​

Within the Menditect Testability Framework, the term Testability aligns with the ISO definition. At the same time, applying the framework also influences the other maintainability subcharacteristics, strengthening overall software quality beyond Testability alone.