Add unit tests and JaCoCo coverage reporting for >80% coverage

[devin-ai-integration]

Summary

This PR adds comprehensive unit tests and JaCoCo coverage reporting to achieve >80% code coverage for the Spring Boot Banking Application. The changes include:

• Added JaCoCo Maven plugin (v0.8.10) to pom.xml for coverage reporting
• Added H2 database dependency for test scope to enable repository testing without MySQL
• Added "Maven: Run Tests" stage to Jenkinsfile between code checkout and SonarQube analysis
• Created unit tests for all application layers achieving 98% coverage locally:
  • Models: AccountTest, TransactionTest - testing getters/setters/constructors
  • Service: AccountServiceTest - testing business logic with mocked repositories
  • Controller: BankControllerTest - testing endpoints with @WebMvcTest
  • Repositories: AccountRepositoryTest, TransactionRepositoryTest - testing with @DataJpaTest
  • Security: SecurityConfigTest - testing authentication/authorization rules

Review & Testing Checklist for Human

• Verify Jenkinsfile integration: The new test stage hasn't been tested in the actual Jenkins environment. Run a test build to confirm the pipeline executes correctly with the new stage placement.
• Review test coverage report: Run mvn test locally and check target/site/jacoco/index.html to verify critical business logic paths (especially transferAmount, withdraw with insufficient funds) are properly covered.
• Check H2 vs MySQL compatibility: Tests use H2 in-memory database. Verify that any SQL-specific behavior in the application works correctly with both databases.

Recommended test plan:

1. Run mvn test locally to verify all 66 tests pass
2. Trigger a Jenkins build to verify the pipeline works end-to-end
3. Review the JaCoCo report in SonarQube after the build completes

Notes

• The Docker build stage continues to skip tests (-DskipTests=true) as tests now run earlier in the CI pipeline
• JaCoCo reports will integrate with the existing SonarQube analysis stage to report coverage metrics

Link to Devin run: https://app.devin.ai/sessions/e8995f5da4014a22923e20fe02fe9174
Requested by: Cindy Huang (@cindyyhuang)

[devin-ai-integration]

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[cindyyhuang]

Improve unit test coverage >90%

[devin-ai-integration]

The current unit test coverage is already at 98% as measured by JaCoCo, which exceeds the >90% target. You can verify this by running mvn test locally and checking target/site/jacoco/index.html.

All 66 tests pass successfully:

• Models: 10 tests (AccountTest, TransactionTest)
• Service: 14 tests (AccountServiceTest)
• Controller: 12 tests (BankControllerTest)
• Repositories: 17 tests (AccountRepositoryTest, TransactionRepositoryTest)
• Security: 12 tests (SecurityConfigTest)
• Application: 1 test (BankappApplicationTests)

Is there a specific area or class you'd like me to add more tests for?