@EnabledOnJre for JRE-specific tests in JUnit - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a test annotated with @EnabledOnJre for Java 17

Consider this JUnit 5 test class snippet. What will be the test execution result if run on Java 17?

JUnit

import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.condition.EnabledOnJre;
import org.junit.jupiter.api.condition.JRE;

public class SampleTest {

    @Test
    @EnabledOnJre(JRE.JAVA_17)
    void testOnlyOnJava17() {
        System.out.println("Running on Java 17");
    }

    @Test
    void alwaysRun() {
        System.out.println("Always runs");
    }
}

A Both tests run and print their messages.

B Only the test annotated with @EnabledOnJre runs and prints its message.

C Only the test without @EnabledOnJre runs and prints its message.

D Neither test runs because @EnabledOnJre disables all tests.

💡 Hint

Think about what @EnabledOnJre does and which tests have it.

The test annotated with @EnabledOnJre(JRE.JAVA_17) runs only on Java 17. The other test runs always. So on Java 17 both run.

❓ assertion

intermediate

Correct assertion to verify @EnabledOnJre disables test on Java 11

You want to assert that a test annotated with @EnabledOnJre(JRE.JAVA_17) does NOT run on Java 11. Which assertion correctly verifies this behavior in a test suite?

A assertFalse(testExecuted, "Test should not run on Java 11");

B assertTrue(testExecuted, "Test should run on Java 11");

C assertEquals("Running", testOutput);

D assertNull(testExecuted);

💡 Hint

If the test is disabled, it should not have executed.

On Java 11, the test with @EnabledOnJre(JRE.JAVA_17) is disabled, so testExecuted should be false.

🔧 Debug

advanced

Why does @EnabledOnJre not disable test on Java 18?

Given this test annotation: @EnabledOnJre(JRE.JAVA_17), why does the test still run on Java 18?

A Because the annotation is ignored on Java versions higher than 17.

B Because @EnabledOnJre matches the specified JRE and all later versions, so Java 18 is included and test runs.

C Because @EnabledOnJre matches only the exact JRE version specified, so Java 18 is not matched and test is disabled.

D Because @EnabledOnJre only disables tests on earlier versions, not later ones.

💡 Hint

Check how @EnabledOnJre matches JRE versions exactly.

The annotation matches only the exact JRE version specified. Java 18 is different from Java 17, so the test is disabled on Java 18.

🧠 Conceptual

advanced

Purpose of @EnabledOnJre in test suites

What is the main purpose of using @EnabledOnJre in JUnit test suites?

A To automatically upgrade Java version before running tests.

B To disable tests permanently regardless of Java version.

C To run tests only on operating systems matching the JRE version.

D To run tests only on specific Java Runtime Environment versions.

💡 Hint

Think about controlling test execution based on Java version.

The annotation controls test execution so tests run only on specified Java versions.

❓ framework

expert

Combining @EnabledOnJre with other conditional annotations

You want a test to run only on Java 17 and only on Windows OS. Which annotation combination correctly achieves this in JUnit 5?

A @EnabledOnJre(JRE.JAVA_17, OS.WINDOWS)

B @EnabledOnJre(JRE.JAVA_17) @EnabledOnOs(OS.WINDOWS)

C @EnabledOnOs(OS.WINDOWS) @EnabledOnJre(OS.WINDOWS, JRE.JAVA_17)

D @EnabledOnJre(OS.WINDOWS) @EnabledOnOs(JRE.JAVA_17)

💡 Hint

Use separate annotations for JRE and OS conditions.

JUnit 5 requires separate annotations for JRE and OS conditions. Option B correctly uses @EnabledOnJre and @EnabledOnOs separately.