Use Case Development

Develop comprehensive use cases that describe system behavior, user interactions, and business scenarios for clear requirements specification.

When to Use This Skill

• Defining system functionality

• Describing user interactions

• Specifying requirements

• Planning test scenarios

• Communicating with stakeholders

• Designing system behavior

• Creating user documentation

• Estimating development effort

Core Concepts

1. Use Case Structure

Use Case ID: UC-001 Use Case Name: Process Customer Order Actor: Customer, Sales Rep Preconditions: User is logged in, Items in cart Postconditions: Order created, Payment processed

Main Success Scenario:

1. Customer reviews cart
2. Customer proceeds to checkout
3. System validates cart items
4. Customer enters shipping address
5. Customer selects payment method
6. System processes payment
7. System creates order
8. System sends confirmation email

Alternative Flows: 3a. Invalid items in cart 3a1. System removes invalid items 3a2. System notifies customer 3a3. Resume at step 1

6a. Payment fails 6a1. System displays error 6a2. Customer selects different payment 6a3. Resume at step 6

Exception Flows:

• Network timeout: Save cart, allow retry
• Out of stock: Notify customer, suggest alternatives

2. Use Case Diagram

Actor: Customer | +-- (Browse Products) +-- (Add to Cart) +-- (Checkout) +-- (Track Order)

Actor: Admin | +-- (Manage Products) +-- (Process Returns) +-- (View Reports)

Best Practices

• Focus on user goals - What user wants to accomplish

• Be technology-independent - Don't specify UI details

• Include alternatives - Error cases and variations

• Keep atomic - One clear goal per use case

• Define preconditions - Required state before execution

• Specify postconditions - Expected state after

• Number steps - Easy reference and traceability

• Validate with users - Ensure completeness

Resources

• Writing Effective Use Cases: Alistair Cockburn

• UML Use Case Diagrams: OMG specification