1. How to Be a Java Automated Testing
Superstar!
Billy Korando
Oracle - Java Developer Advocate ☕🥑
@BillyKorando

2. • Ask questions
• Reach out:
Twitter: @BillyKorando
Email: billy.korando@oracle.com
• Key link 👉 https://github.com/wkorando/java-testing-superstar
Important Notes
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3. Copyright © 2021, Oracle and/or its affiliates
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https://billykorando.com/

4. My code is perfect!
Why should I waste time writing tests?
Why Write Automated Tests?
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• Substantial time and effort to write tests
• Substantial time and effort to maintain tests

5. 🏠
Why Write Automated Tests?
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CI/CD Process =>
🧱🧱🧱🧱🧱🧱
🧱🧱🧱🧱🧱🧱🧱🧱
🧱🧱🧱🧱🧱🧱🧱🧱
Automated Tests =>

6. Deployment Process
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🌎
Deploy to Prod
👩💻🧑💻
👨💻
Developers
Commit Code
🔨
Build & Test
Code
✅✅
✅
🛴
Manual Process
Takes hours or days

7. The code
your code
runs on
The Dependency Iceberg
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Your Code
{
• Security patches
• Performance
enhancements
• Feature
enhancements

8. Manual Test Costs
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The high effort of regression testing code
disincentivizes keeping dependencies up-to-date

9. Deployment Process
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🌎
Deploy to Prod
👩💻🧑💻
👨💻
Developers
Commit Code
🔨
Build & Test
Code
✅✅
✅
🏍
Automated Process
Measured in minutes

10. Auditable 🕵
• Can review test code, reports, and logging
Repeatable ↻
• Can re-run test suite to see if problems persists
• Can run test suite against other code base/version to see if problem exists
Additional Benefits
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11. Whatever gives you confidence to
deploy to PROD without manual
intervention
How Many Automated Test Should I Write?
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12. Manual testing still needed.
But it’s exploratory testing.
Manual Testing
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13. How to be an Automated Testing
Superstar?
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14. ✅ Treat Test Code like “Production” Code
✅ Write Human Readable Tests
How to be an Automated Testing Superstar?
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15. • Parallel test execution
• Repeated tests
• Extensions
• Selective disabling
• Default test methods
• And more!
JUnit 5 Not Covered
[Date]
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16. AssertJ – Fluent Assertions
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17. AssertJ – Fluent Assertions
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18. ✅ Write Reliable Tests
How to be an Automated Testing Superstar?
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19. Test Containers
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20. Test Containers
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• Test against local containerized instances of remote services
• Don’t have to worry about:
• Service being down
• Test data going missing
• Maintain local instance

21. JFRUnit
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22. JFRUnit
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• Capture JDK Flight Recorder (JFR) Events to track system performance behavior
• Check JVM behavior consistent across systems and environments

23. Contract Driven Development (Spring Cloud Contract)
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24. Contract Driven Development (Spring Cloud Contract)
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• Contracts validate service fulfill defined behavior
• Contracts can be used to setup up mock of service

25. Junit 5, Mockito, AssertJ, and Test Containers:
https://github.com/wkorando/welcome-to-junit5-v2
Spring Cloud Contract Example:
https://github.com/wkorando/collaborative-contract-driven-development-2-0
JFRUnit:
https://github.com/wkorando/testing-tuesday/tree/main/xxx-jfr-unit
Code Examples
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26. Thank you
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