What is a use case?

Use Case in software development is a description of how a user or another external system (Actor) interacts with the system to achieve a specific goal.

Key elements:

• Actor: User, system, or any other external entity interacting with the system.
• Goal: What the Actor tries to achieve by interacting with the system.
• Scenario: A sequence of steps describing the interaction between the Actor and the system to achieve the goal. There can be a main scenario (Happy Path) and alternative scenarios (Alternative Flows, Exception Flows).

Example:

Use Case: User makes a purchase.

• Actor: Buyer

• Goal: Successfully purchase the product.

• Main Success Scenario:

  1. The buyer finds the product.
  2. The buyer adds the product to the cart.
  3. The buyer proceeds to checkout.
  4. The buyer enters delivery details.
  5. The buyer selects a payment method.
  6. The buyer confirms the order.
  7. The system processes the payment.
  8. The system confirms the successful order placement.

• Alternative Scenarios:

  • The buyer enters incorrect delivery details.
  • The payment is declined by the bank.
  • The product runs out of stock during checkout.

Use cases help to:

• Understand system requirements.
• Define system functionality.
• Plan testing.