A testable requirement, often referred to as a “testable specification” or “testable user story,” is a requirement or specification for a software system that is clearly and unambiguously defined in a way that allows for the creation of test cases to verify whether the requirement has been met. Testable requirements are essential in software development because they ensure that the software can be systematically and objectively tested to validate its functionality.
Key characteristics of testable requirements include:
- Clarity and Precision: Testable requirements are written in a clear and precise manner, leaving no room for interpretation or ambiguity. This clarity makes it easier to design test cases.
- Measurability: Testable requirements define criteria that can be objectively measured to determine whether the requirement has been satisfied or not. This includes specifying expected results or outcomes.
- Specificity: Testable requirements are specific about what the software is expected to do. They provide detailed information on the behavior or functionality expected, including input conditions and expected outputs.
- Independence: Testable requirements are independent of one another, meaning they can be tested individually without significant dependencies on other requirements. This allows for efficient testing.
- Verifiability: Testable requirements are verifiable, meaning that it is possible to create test cases to check whether the requirement has been met. Verification should be feasible and practical.
- Completeness: Testable requirements cover all relevant aspects of the functionality they describe. They do not omit important details that are necessary for proper testing.
- Testability Considerations: Testable requirements take into account the testing process. They consider how the functionality can be tested, including which inputs and scenarios need to be tested.
For example, let’s consider a non-testable requirement and its transformation into a testable requirement:
Non-Testable Requirement:
- “The system should be user-friendly.”
This requirement lacks clarity, measurability, and specificity, making it challenging to create test cases to determine whether the software is user-friendly.
Testable Requirement:
- “The system should provide a user interface where users can complete common tasks within an average of three clicks. Users should be able to navigate from the homepage to the desired functionality with clear menu options and minimal user input.”
This testable requirement provides specific criteria for measuring user-friendliness, such as the number of clicks and ease of navigation, making it suitable for the creation of test cases to verify its fulfillment.
By defining testable requirements, software development teams can better plan, design, and execute testing activities, leading to a more efficient and effective testing process and improved software quality. It also helps in reducing misunderstandings and misinterpretations between different stakeholders in a software project.