Difference between Use Case and Test Case

Use Cases and Test Cases are two important terms in software testing. A use case describes how a system should behave to perform a certain task under given conditions. A test case contains the actual test data, step-by-step instructions, and the expected result to verify that the system works correctly.

Use Case

A use case is a representation of actions that describes the behavior of a system when performing a particular task. It is written from the end user's perspective and focuses on what the system should do, not how it does it internally. Use cases are prepared from requirement documents.

Example

Use Case: User Login

Actor:       Registered User
Precondition: User has a valid account

Steps:
1. User navigates to the login page
2. User enters username and password
3. User clicks the "Login" button
4. System validates credentials

Expected Result: User is redirected to the dashboard
Alternate Flow:  If credentials are invalid, show error message

Test Case

A test case contains specific test data, a set of instructions to follow, and the expected result for each step. Test cases are prepared based on use cases and are executed by testers to verify that the system meets requirements.

Example

Test Case ID:    TC_LOGIN_001
Test Case Name:  Verify successful login
Precondition:    User account exists (user: john, pass: Pass@123)

Steps:
1. Open browser and navigate to /login
2. Enter username: "john"
3. Enter password: "Pass@123"
4. Click "Login" button

Test Data:       username=john, password=Pass@123
Expected Result: Dashboard page loads with "Welcome, John"
Actual Result:   [Filled during execution]
Status:          [Pass/Fail]

Key Differences

Conclusion

Use cases define what the system should do from a user's perspective and are created during the requirements phase. Test cases verify that the system actually does it correctly and are created during the testing phase based on use cases. Together, they ensure that requirements are properly captured and validated.