Coverage thresholds in JUnit - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

JUnit Coverage Threshold Failure Output

Given the following JUnit test coverage configuration, what will be the test execution result if the coverage is 74% for branch coverage?

JUnit

jacoco {
  toolVersion = "0.8.8"
  reports {
    xml.required.set(true)
    html.required.set(true)
  }
  coverageVerification {
    violationRules {
      rule {
        limit {
          counter = 'BRANCH'
          value = 'COVERED_RATIO'
          minimum = '0.75'
        }
      }
    }
  }
}

A Test execution passes but with a warning about coverage.

B Test execution passes successfully with no errors.

C Test execution is skipped because coverage is below threshold.

D Test execution fails due to branch coverage below 75%.

💡 Hint

Coverage verification rules enforce minimum coverage thresholds strictly.

The coverageVerification rule requires branch coverage to be at least 75%. Since actual coverage is 74%, the build fails.

❓ assertion

intermediate

Assertion on Coverage Percentage in JUnit Test Report

Which assertion correctly verifies that the line coverage percentage is at least 80% in a JUnit test report parsed as a float variable named coverageLinePercent?

A assertFalse(coverageLinePercent < 80.0);

B assertEquals(coverageLinePercent, 80.0);

C assertTrue(coverageLinePercent >= 80.0);

D assertNotNull(coverageLinePercent > 80.0);

💡 Hint

Use an assertion that checks a condition is true for coverage threshold.

assertTrue with condition coverageLinePercent >= 80.0 correctly asserts coverage meets or exceeds 80%.

🔧 Debug

advanced

Debugging Coverage Threshold Failure in JUnit

A JUnit test suite fails with a coverage threshold violation error, but the reported coverage is 85%. What is the most likely cause?

A The coverage report file is missing or corrupted, causing a false failure.

B The coverage threshold is set higher than 85%, causing failure.

C The test suite has syntax errors unrelated to coverage.

D JUnit does not support coverage thresholds, so the error is invalid.

💡 Hint

Check the configured minimum coverage value in the build tool.

If the threshold is set above 85%, coverage at 85% will fail the check.

❓ framework

advanced

Configuring Coverage Thresholds in JUnit with JaCoCo

Which snippet correctly configures JaCoCo in a Gradle build to fail the build if instruction coverage is below 90%?

A

jacocoTestCoverageVerification {
  violationRules {
    rule {
      limit {
        counter = 'INSTRUCTION'
        value = 'COVERED_RATIO'
        minimum = '0.9'
      }
    }
  }
}

B

jacocoTestCoverageVerification {
  violationRules {
    rule {
      limit {
        counter = 'INSTRUCTION'
        value = 'COVERED_RATIO'
        minimum = 0.9
      }
    }
  }
}

C

jacocoTestCoverageVerification {
  violationRules {
    rule {
      limit {
        counter = 'INSTRUCTION'
        value = 'COVERED_PERCENTAGE'
        minimum = '90'
      }
    }
  }
}

D

jacocoTestCoverageVerification {
  violationRules {
    rule {
      limit {
        counter = 'INSTRUCTION'
        value = 'COVERED_RATIO'
        minimum = 90
      }
    }
  }
}

💡 Hint

Minimum must be a string representing a decimal ratio between 0 and 1.

JaCoCo expects minimum coverage as a string decimal like '0.9' for 90%.

🧠 Conceptual

expert

Impact of Coverage Thresholds on Continuous Integration

Which statement best describes the impact of strict coverage thresholds in a CI pipeline using JUnit and JaCoCo?

A Strict thresholds ensure high code quality but may cause frequent build failures requiring quick fixes.

B Strict thresholds have no impact on build stability or developer workflow.

C Strict thresholds automatically fix coverage gaps without developer intervention.

D Strict thresholds reduce test execution time by skipping low coverage tests.

💡 Hint

Consider how coverage enforcement affects build success and developer actions.

Strict coverage thresholds enforce quality but can cause builds to fail if coverage drops, prompting developers to fix tests or code.