Parallel test configuration in JUnit - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is parallel test configuration in JUnit?

It is a setup that allows multiple tests to run at the same time to save time and improve efficiency.

beginner

How do you enable parallel test execution in JUnit 5?

By configuring the junit-platform.properties file with junit.jupiter.execution.parallel.enabled = true.

intermediate

What is the purpose of ExecutionMode.CONCURRENT in JUnit?

It tells JUnit to run tests or test classes at the same time instead of one after another.

intermediate

Name one risk of running tests in parallel.

Tests might interfere with each other if they share data or resources, causing false failures.

advanced

How can you control the number of threads used in JUnit parallel tests?

By setting junit.jupiter.execution.parallel.config.fixed.parallelism in the junit-platform.properties file.

Which file is used to configure parallel execution in JUnit 5?

A pom.xml

B junit-platform.properties

C build.gradle

D testng.xml

JUnit 5 uses the junit-platform.properties file to set parallel execution options.

What does setting junit.jupiter.execution.parallel.enabled = true do?

A Enables parallel test execution

B Disables parallel test execution

C Runs tests sequentially

D Skips tests

This property enables running tests in parallel in JUnit 5.

Which JUnit annotation or setting controls if tests run concurrently?

A ExecutionMode.CONCURRENT

B @TestInstance

C @BeforeEach

D @Disabled

ExecutionMode.CONCURRENT tells JUnit to run tests concurrently.

What is a common problem when running tests in parallel?

A Tests run slower

B Tests lose coverage

C Tests cannot run on multiple threads

D Tests may share state causing failures

Shared state or resources can cause tests to interfere and fail when run in parallel.

How do you limit the number of threads used in parallel tests in JUnit?

A Use @ThreadLimit annotation

B Set <code>parallel.threads</code> in pom.xml

C Set <code>junit.jupiter.execution.parallel.config.fixed.parallelism</code>

D Set <code>maxThreads</code> in build.gradle

This property controls the fixed number of threads for parallel test execution.

Explain how to enable and configure parallel test execution in JUnit 5.

Think about the properties file and execution modes.

What are the benefits and risks of running tests in parallel?

Consider speed vs test reliability.