Custom conditions with @EnabledIf in JUnit - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a test with @EnabledIf condition

Consider the following JUnit 5 test method using @EnabledIf. What will be the test execution result when the system property 'env' is set to 'prod'?

JUnit

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

public class EnvTest {

    @Test
    @EnabledIf(expression = "'prod'.equals(System.getProperty('env'))", reason = "Only runs in prod environment")
    void testOnlyInProd() {
        System.out.println("Running in prod");
    }
}

A Test is skipped and does not run

B Test runs and passes, printing 'Running in prod'

C Test runs but fails with an exception

D Test runs and passes but prints nothing

💡 Hint

Check what the @EnabledIf expression evaluates to when 'env' is 'prod'.

The @EnabledIf annotation runs the test only if the expression evaluates to true. Since System.getProperty('env') returns 'prod', the expression 'prod'.equals('prod') is true, so the test runs and prints the message.

❓ assertion

intermediate

Assertion to verify @EnabledIf disables test

You want to assert that a test annotated with @EnabledIf(expression = "false") does not run. Which assertion correctly verifies this behavior in a JUnit 5 test suite?

A assertThrows(TestAbortedException.class, () -> runTest())

B assertTrue(runTest())

C assertFalse(runTest())

D assertEquals("Skipped", runTest())

💡 Hint

Tests disabled by @EnabledIf are aborted, not failed or passed.

When a test is disabled by @EnabledIf, JUnit aborts the test execution by throwing TestAbortedException. So asserting that this exception is thrown confirms the test was skipped.

🔧 Debug

advanced

Debug why @EnabledIf expression fails to enable test

Given this test method with @EnabledIf: @Test @EnabledIf(expression = "systemProperties['user.name'] == 'admin'", reason = "Only admin user") void adminOnlyTest() {} The test never runs even when the system property 'user.name' is set to 'admin'. What is the likely cause?

A The expression uses '==' instead of '.equals()' for string comparison

B The system property 'user.name' is not accessible in the test environment

C The @EnabledIf annotation requires a static method, missing here

D The test method must be static to use @EnabledIf

💡 Hint

Remember how string equality works in Java expressions.

In Java, '==' compares object references, not string content. The expression should use '.equals()' to compare string values. Using '==' causes the expression to be false, so the test is disabled.

🧠 Conceptual

advanced

Understanding @EnabledIf expression context

Which of the following statements about the expression used in @EnabledIf is TRUE?

A The expression can only check JUnit test annotations, not system properties

B The expression can execute arbitrary Java code including method calls with side effects

C The expression must be a constant boolean literal (true or false) only

D The expression can access system properties and environment variables via predefined variables

💡 Hint

Think about what data the expression can read to decide test execution.

The expression in @EnabledIf can access system properties and environment variables through predefined variables like 'systemProperties' and 'environment'. It cannot execute arbitrary Java code or have side effects.

❓ framework

expert

Custom condition class for @EnabledIf usage

You want to create a custom condition class to use with @EnabledIf to enable tests only on weekdays. Which implementation correctly defines the condition method?

JUnit

import org.junit.jupiter.api.extension.ConditionEvaluationResult;
import org.junit.jupiter.api.extension.ExecutionCondition;
import org.junit.jupiter.api.extension.ExtensionContext;
import java.time.DayOfWeek;
import java.time.LocalDate;

public class WeekdayCondition implements ExecutionCondition {

    @Override
    public ConditionEvaluationResult evaluateExecutionCondition(ExtensionContext context) {
        DayOfWeek day = LocalDate.now().getDayOfWeek();
        if (day == DayOfWeek.SATURDAY || day == DayOfWeek.SUNDAY) {
            return ConditionEvaluationResult.disabled("Weekend - test disabled");
        } else {
            return ConditionEvaluationResult.enabled("Weekday - test enabled");
        }
    }
}

A The class extends ConditionEvaluationResult and overrides isEnabled to check the day

B The class implements TestExecutionListener and overrides beforeTestExecution to skip tests on weekends

C The class implements ExecutionCondition and overrides evaluateExecutionCondition returning enabled or disabled based on day

D The class implements ExecutionCondition but returns null from evaluateExecutionCondition

💡 Hint

Check the interface and method required for custom conditions in JUnit 5.

To create a custom condition for @EnabledIf, implement ExecutionCondition and override evaluateExecutionCondition to return enabled or disabled results. Returning null or wrong interface will not work.