### Relevant Articles:

- [Guide to the System Rules Library](https://www.baeldung.com/java-system-rules-junit)
- [Guide to the System Stubs Library](https://www.baeldung.com/java-system-stubs)
- [Code Coverage with SonarQube and JaCoCo](https://www.baeldung.com/sonarqube-jacoco-code-coverage)
- [Exclusions from Jacoco Report](https://www.baeldung.com/jacoco-report-exclude)
- [Gray Box Testing Using the OAT Technique](https://www.baeldung.com/java-gray-box-orthogonal-array-testing)
- [Unit Testing of System.in With JUnit](https://www.baeldung.com/java-junit-testing-system-in)
- [Fail Maven Build if JUnit Coverage Falls Below Certain Threshold](https://www.baeldung.com/maven-junit-fail-build-coverage-threshold)
- [How to Mock Environment Variables in Unit Tests](https://www.baeldung.com/java-unit-testing-environment-variables)