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Top 30 Jacoco Interview Questions with Answers multiple choice style

1. What is JaCoCo?

a. A code coverage tool for Java
b. A version control system
c. A Java compiler
d. An integrated development environment
Answer: a

2. Which type of code coverage does JaCoCo primarily measure?

a. Statement coverage
b. Branch coverage
c. Line coverage
d. Function coverage
Answer: a

3. What does code coverage measure?

a. Code quality
b. Code performance
c. Code execution coverage
d. Code maintainability
Answer: c

4. Which format does JaCoCo use to store coverage information?

a. XML
d. Exec
Answer: d

5. How do you include JaCoCo in your Java project for code coverage measurement?

a. Add it to your project's dependencies
b. Set a specific compiler flag
c. Import it using an import statement
d. It is automatically included in all Java projects
Answer: a

6. Which build tools are supported by JaCoCo for code coverage measurement?

a. Maven and Gradle
b. Ant and Make
c. IntelliJ and Eclipse
d. None of the above
Answer: a

7. In JaCoCo, what does "instruction coverage" measure?

a. The number of executed bytecode instructions
b. The number of source code lines executed
c. The number of methods called
d. The number of branches taken
Answer: a

8. What is "branch coverage" in JaCoCo?

a. It measures the percentage of branches that have been executed
b. It measures the number of branches in the code
c. It measures the code complexity
d. It measures the number of conditionals in the code
Answer: a

9. Which JaCoCo report format is most suitable for a human-readable summary of code coverage?

a. XML
d. CSV
Answer: b

10. What is the purpose of the JaCoCo "exec" file?

a. It contains source code
b. It stores coverage execution data
c. It is a configuration file
d. It contains code comments
Answer: b

11. How can you generate an HTML coverage report using JaCoCo?

a. Use the "mvn jacoco:report" command
b. Execute a Gradle task
c. Manually create an HTML file
d. Use the "javac" command
Answer: a

12. Which metric indicates the percentage of covered lines in JaCoCo?

a. Statement coverage
b. Branch coverage
c. Line coverage
d. Instruction coverage
Answer: c

13. What is the minimum acceptable code coverage percentage for a project, according to best practices?

a. 50%
b. 75%
c. 90%
d. 100%
Answer: c

14. How does JaCoCo distinguish between covered and uncovered code?

a. By instrumenting the bytecode
b. By analyzing source code comments
c. By using regular expressions
d. By checking code annotations
Answer: a

15. Which JaCoCo component allows you to exclude specific classes or methods from coverage analysis?

a. Filters
b. Exclusions
c. Annotations
d. Rules
Answer: b

16. What does a red bar in the JaCoCo HTML report signify?

a. Fully covered code
b. Partially covered code
c. Uncovered code
d. Code that needs refactoring
Answer: c

17. Which type of coverage focuses on the number of method invocations exercised during testing?

a. Line coverage
b. Method coverage
c. Function coverage
d. Class coverag
Answer: b

18. Which command can be used to generate a JaCoCo report with Gradle?

a. gradle jacoco
b. gradle build --coverage
c. gradle test jacoco
d. gradle report
Answer: c

19. How does JaCoCo handle code that is executed only during exception handling?

a. It includes it in coverage analysis
b. It excludes it from coverage analysis
c. It raises an error
d. It generates a warning
Answer: b

20. In JaCoCo, what is "complexity coverage"?

a. A measure of code readability
b. A measure of code performance
c. A measure of code complexity
d. A measure of code style
Answer: c

21. Which JaCoCo report format is most suitable for integration with continuous integration (CI) tools?

a. XML
d. CSV
Answer: a

22. Which Java version is required for JaCoCo to work properly?

a. Java 5 and above
b. Java 6 and above
c. Java 7 and above
d. Java 8 and above
Answer: b

23. How does JaCoCo handle code coverage for interfaces?

a. It does not analyze code coverage for interfaces
b. It analyzes code coverage based on the implementing classes
c. It treats interfaces like regular classes
d. It analyzes code coverage based on the interface itself
Answer: b

24. What does JaCoCo's "transitive runtime" option do?

a. It ignores runtime dependencies
b. It includes runtime dependencies
c. It analyzes transitive dependencies
d. It generates a warning for runtime dependencies
Answer: a

25. Which JaCoCo report format can be easily consumed by other tools for further analysis?

a. XML
d. CSV
Answer: c

26. What is the purpose of the JaCoCo "maven-surefire-plugin" in a Maven project?

a. It generates HTML reports
b. It configures code coverage exclusions
c. It runs test classes
d. It enforces code coverage thresholds
Answer: c

27. What is the primary benefit of using JaCoCo for code coverage analysis?

a. It improves code execution speed
b. It enhances code readability
c. It helps identify untested code
d. It enforces coding standards
Answer: c

28. Which JaCoCo feature allows you to track coverage trends over time?

a. Historical coverage reports
b. Continuous integration
c. Code review process
d. Custom code annotations
Answer: a

29. In JaCoCo, what does "method coverage" measure?

a. The number of methods in a class
b. The percentage of methods covered by tests
c. The method invocation count
d. The code complexity within methods
Answer: b

30. How can you specify custom code coverage goals and thresholds in JaCoCo?

a. By using annotations in the code
b. By modifying the JaCoCo source code
c. By configuring the JaCoCo Maven or Gradle plugin
d. By editing the JaCoCo HTML report
Answer: c

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