Use Cases

✅ 1. What is a Use Case?

📌 Definition:

A Use Case is a description of how a user (actor) interacts with a system to achieve a specific goal. It captures functional requirements and focuses on user-system interaction to ensure that the system delivers value to its users.

💡 Goal: Describe what the system will do from a user’s perspective, step by step.

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✅ 2. Key Components of a Use Case

Component	Description
Use Case ID	Unique identifier for reference.
Use Case Name	Brief, descriptive title of the use case.
Actors	Users or other systems interacting with the system.
Description	Short summary of what the use case does.
Pre-conditions	What must be true before the use case starts.
Post-conditions	State of the system after successful completion.
Basic Flow (Main Flow)	Normal sequence of steps from start to finish.
Alternative Flows	Variations, exceptions, or errors that may occur.
Assumptions	Things assumed to be true for the use case to work.
Priority	Importance or rank of the use case.

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✅ 3. Why are Use Cases Important?

Purpose	Benefit
Clarify functional requirements	Ensure clear understanding of system behavior.
Bridge communication gaps	Help business and technical teams align.
Identify system interactions	Understand how users will use the system.
Basis for test case development	Used to create scenarios for system testing.
Support user interface design	Understand user journeys for better UX.

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✅ 4. Basic Structure of a Use Case (Example Template)

sqlCopyEditUse Case ID: UC-001
Use Case Name: User Login
Actor: Registered User
Description: This use case describes how a registered user logs into the system.
Pre-conditions:
- User must have an active account.
- User must have valid login credentials.

Post-conditions:
- User is authenticated and redirected to their dashboard.

Basic Flow:
1. User navigates to the login page.
2. User enters their email and password.
3. User clicks the "Login" button.
4. System validates the credentials.
5. System grants access and redirects to the dashboard.

Alternative Flows:
4a. Invalid Credentials:
    - System shows an error message: "Invalid email or password."
    - User can retry.

Assumptions:
- System is available and online.
Priority: High

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✅ 5. Types of Use Cases

Type	Purpose
Business Use Cases	Describe high-level business processes involving multiple actors and systems.
System Use Cases	Focus on interactions between users and the system to achieve specific goals.

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✅ 6. Actors in Use Cases

🔹 Primary Actor:

• Main user who initiates the interaction to achieve a goal.

Example: "Customer" logging into an e-commerce site.

🔹 Secondary Actor:

• Other systems or users that assist the primary actor.

Example: "Payment Gateway" in an online purchase process.

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✅ 7. Use Case Diagram (Visual Representation)

📊 Purpose:

• Show interactions between actors and system functions in a graphical form.

📌 Elements:

Symbol	Meaning
Oval	Use case (function/process).
Stick Figure	Actor (user/system).
Line	Interaction/association.

Example (Text Description of Diagram):

scssCopyEditActor (User) ----> (Login)
Actor (User) ----> (Place Order)
Actor (Admin) ---> (Manage Products)

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✅ 8. Difference Between Use Case and User Story

Aspect	Use Case	User Story
Format	Detailed step-by-step interaction.	Short sentence: "As a [user], I want [goal], so that [benefit]."
Focus	Interaction and flow of events.	User need and value.
Detail Level	More formal and detailed.	Short and simple.
Purpose	Capture detailed system behavior.	Capture a high-level requirement or goal.

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✅ 9. Benefits of Use Cases for Business Analysts (BA)

Benefit	Explanation
Clear understanding of requirements	Ensures precise definition of user and system interactions.
Improves communication	Acts as a common language for business and technical teams.
Identifies functional gaps	Highlights missing or incomplete functionalities.
Helps in test planning	Used to create test cases and scenarios.
Guides UI/UX design	Shows step-by-step user journey.

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✅ 10. Tools for Creating Use Cases and Diagrams

Tool Type	Examples	Purpose
Diagram Tools	Lucidchart, Microsoft Visio, Draw.io, Creately	Create visual use case diagrams.
Requirement Tools	Jira, Confluence, IBM DOORS, Azure DevOps	Document and manage use cases and requirements.
Modeling Tools	Enterprise Architect, Visual Paradigm	Advanced system modeling.

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✅ 11. Common Mistakes in Writing Use Cases and How to Avoid Them

Mistake	Solution
Too much technical detail	Focus on what the system does, not how.
Vague descriptions	Be specific and clear in each step.
Ignoring alternative flows	Include exceptions and errors handling.
Not involving stakeholders	Collaborate with users for accurate flows.
Incomplete pre/post-conditions	Clearly define starting and ending states.

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✅ 12. Summary of Use Cases

Aspect	Details
Purpose	Describe user interactions with the system to achieve goals.
Key Elements	Actors, steps, pre/post-conditions, alternative flows.
Benefits	Clarify functional requirements, improve communication, guide testing.
Tools	Lucidchart, Visio, Jira, Confluence.