Non Functional Requirements
Understanding non-functional requirements (NFRs) in software testing, covering types, measurement, and business impact for effective quality assurance.
Mark
Performance Testing Expert
Testing should be requirements driven and measurable. This foundational principle is essential for quality assurance.
Types of NFRs
Non-functional requirements cover many categories:
- Scalability - Ability to handle increased load
- Reliability - Consistent performance over time
- Regulatory Compliance - Meeting legal and industry standards
- Recoverability - Ability to recover from failures
- Capacity - Maximum load the system can handle
- Maintainability - Ease of making changes
- Serviceability - Ease of servicing and support
- Security - Protection against threats
- Data Integrity - Accuracy and consistency of data
- Interoperability - Ability to work with other systems
- Availability - System uptime percentage
- Usability - Ease of use for end users
Practical Example
A concrete, measurable NFR example: an API must handle 1,000 concurrent transactions per second with one-second response times.
Implementation Approach
The recommended process involves collaboration between business stakeholders, developers, and testers to document business processes and create requirement mappings. This can be accomplished simply using spreadsheet-based tracking.
Addressing Gaps
When communication breaks down between teams, business analysts or senior testers should bridge the gap by gathering business needs and translating them into actionable, measurable specifications.
Business Value
Clear NFRs reduce rework and associated costs by establishing shared understanding of expected product behavior across the organization.
Related Resources
- Nielsen Norman Group’s response time research
- Industry guides on non-functional requirements approaches
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