Test Data

Test Data is the set of input values used to execute test cases and validate application behavior against expected results.

Test data answers: “With what data should this test be executed?”

1. Definition

Test Data is the set of input values used to execute test cases and validate application behavior against expected results.

Test data answers: “With what data should this test be executed?”

2. Purpose of Test Data

• Validate functionality with realistic inputs
• Cover positive, negative, and edge scenarios
• Reproduce defects reliably
• Ensure accurate and meaningful test results

3. Types of Test Data

3.1 Positive Test Data

• Valid and expected inputs
• Used to verify normal system behavior
• Example: Valid username and password

3.2 Negative Test Data

• Invalid or unexpected inputs
• Used to validate error handling
• Example: Invalid email format, empty fields

3.3 Boundary Test Data

• Values at the edge of valid ranges
• Used with BVA
• Example: Min/max length values

3.4 Invalid / Malformed Data

• Special characters, scripts, incorrect formats
• Example: @@@, long strings, SQL-like input

3.5 Realistic / Production-Like Data

• Data resembling real user data (masked)
• Used for realistic validation

4. Sources of Test Data

• Requirements and acceptance criteria
• Business rules
• Existing databases (masked)
• Tester-created synthetic data

5. Test Data Preparation (Manual)

Steps typically include:

1. Identify data requirements per test case
2. Classify data (positive/negative/boundary)
3. Prepare reusable data sets
4. Validate data availability in test environment

6. Manual Tester’s Role

• Identify required data for each test case
• Create and maintain test data
• Ensure data consistency across tests
• Clean up or reset data after execution

7. Test Data vs Test Case

8. Real-Time Example

Registration form test data:

• Valid email: user@test.com
• Invalid email: user@
• Boundary password length: 8, 20
• Duplicate username

9. Common Issues with Test Data

• Insufficient negative data
• Reusing same data repeatedly
• Data dependency between test cases
• Environment data mismatch

10. Best Practices

• Use meaningful and traceable data
• Separate test data from test steps
• Cover all data variations
• Document data clearly

11. Interview-Ready Answers

Short answer:

Test data is the input information used to execute test cases and validate application behavior.

Detailed answer:

Test data consists of valid, invalid, boundary, and realistic inputs used during test execution to ensure accurate and reliable testing results.

12. Key Takeaway

Good Test Data is critical—even the best test case fails without the right data.