Functional requirements

What

• a functional requirement defines a system or its component. It describes the functions a software must perform. A function is nothing but inputs, its behavior, and outputs.

• Example

  • It can be a calculation, data manipulation, business process, user interaction, or any other specific functionality which defines what function a system is likely to perform

  • transaction corrections, adjustments, and cancellations, Business Rules, Certification Requirements, Reporting Requirements, Administrative functions, Authorization levels, Audit Tracking, External Interfaces, Historical Data management, Legal or Regulatory Requirements are various types of functional requirements.

• These requirements state what the system must do, and how it must behave or react to runtime stimuli.

  • functionality does not determine architecture

• Functional software requirements help you to capture the intended behavior of the system. This behavior may be expressed as functions, services or tasks or which system is required to perform.

• It's what the system does

• It is mandatory

• It is captured in use case, easy to capture and product feature

• Helps you verify the functionality of the software

• Focus on user requirement

• Documentation describes what the product does

• Type of Testing involve functional Testing like System, Integration, End to End, API testing, etc.

• defines a system or its component

• Functional requirements along with requirement analysis help identify missing requirements

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Example of Functional Requirements

• The software automatically validates customers against the ABC Contact Management System

• The Sales system should allow users to record customers sales

• The background color for all windows in the application will be blue and have a hexadecimal RGB color value of 0x0000FF.

• Only Managerial level employees have the right to view revenue data.

• The software system should be integrated with banking API

• The software system should pass Section 508 accessibility requirement.

Advantages

• Helps you to check whether the application is providing all the functionalities that were mentioned in the functional requirement of that application

• A functional requirement document helps you to define the functionality of a system or one of its subsystems.

• Functional requirements along with requirement analysis help identify missing requirements. They help clearly define the expected system service and behavior.

• Errors caught in the Functional requirement gathering stage are the cheapest to fix.

• Support user goals, tasks, or activities for easy project management

• Functional requirement can be expressed in Use Case form or user story as they exhibit externally visible functional behavior.