@EnabledIfSystemProperty in JUnit - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding @EnabledIfSystemProperty usage

What does the JUnit annotation @EnabledIfSystemProperty(named = "os.name", matches = "Windows.*") do when applied to a test method?

A Runs the test only if the operating system name starts with "Windows".

B Runs the test only if the system property "os.name" is exactly "Windows".

C Disables the test if the operating system name contains "Windows" anywhere.

D Runs the test regardless of the operating system.

💡 Hint

Think about how the matches attribute uses regular expressions.

The annotation @EnabledIfSystemProperty runs the test only if the specified system property matches the given regular expression. Here, matches = "Windows.*" means the property value must start with "Windows".

❓ Predict Output

intermediate

Test execution with @EnabledIfSystemProperty

Given the following test class, what will be the output when running on a Linux system where os.name is "Linux"?

JUnit

import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.condition.EnabledIfSystemProperty;

public class SystemPropertyTest {

    @Test
    @EnabledIfSystemProperty(named = "os.name", matches = "Windows.*")
    void testWindowsOnly() {
        System.out.println("Windows test executed");
    }

    @Test
    void testAlways() {
        System.out.println("Always executed");
    }
}

A Both "Windows test executed" and "Always executed" are printed.

B Only "Always executed" is printed.

C Only "Windows test executed" is printed.

D No output is printed because tests are skipped.

💡 Hint

Check which tests are enabled based on the system property.

The test annotated with @EnabledIfSystemProperty runs only if os.name matches "Windows.*". On Linux, it does not match, so that test is skipped. The other test runs always.

❓ assertion

advanced

Assertion on test enablement with @EnabledIfSystemProperty

Which assertion correctly verifies that a test method annotated with @EnabledIfSystemProperty(named = "env", matches = "prod") runs only when the system property env is set to "prod"?

A assertTrue(System.getProperty("env").equals("prod"));

B assertTrue(System.getProperty("env").contains("prod"));

C assertFalse(System.getProperty("env").equals("prod"));

D assertNull(System.getProperty("env"));

💡 Hint

The annotation requires exact match to "prod".

The matches attribute expects the system property to exactly match "prod". The assertion must check equality, not containment or null.

🔧 Debug

advanced

Debugging skipped test with @EnabledIfSystemProperty

A test annotated with @EnabledIfSystemProperty(named = "user.language", matches = "en") is unexpectedly skipped on a machine where user.language is "en_US". What is the most likely cause?

A The annotation requires the property to be null to run.

B The system property "user.language" is not set correctly.

C The regex "en" does not match "en_US" because it expects an exact match.

D JUnit does not support regex in @EnabledIfSystemProperty.

💡 Hint

Consider how regex matching works in Java.

The matches attribute uses Java regex which must match the entire string. "en" matches only the exact string "en", not "en_US".

❓ framework

expert

Combining @EnabledIfSystemProperty with other conditional annotations

Consider a test method annotated with both @EnabledIfSystemProperty(named = "env", matches = "prod") and @EnabledOnOs(OS.WINDOWS). Under which condition will this test run?

A When either the system property "env" is "prod" or the OS is Windows.

B Never runs because the annotations conflict.

C Always runs regardless of system property or OS.

D Only when the system property "env" is "prod" and the OS is Windows.

💡 Hint

Think about how multiple conditional annotations combine in JUnit.

JUnit requires all conditional annotations on a test to be true for the test to run. Both conditions must be met.