junit5-concurrent-extension

Junit 5 Extension for @ConcurrentTest

An extension for Junit 5 to execute concurrency tests with ease, by using a single annotation, @ConcurrentTest.

A quick example:

@ExtendWith(ConcurrentExtension.class)
public class ConcurrencyTest {

  static final Object CONSTANT_VALUE = new Object();
  static final ConcurrentHashMap<String, Object> threads = new ConcurrentHashMap<>();

  @ConcurrentTest(count = 10)
  void testConcurrency() {
    String threadId = "Thread#" + Thread.currentThread().getId();
    threads.putIfAbsent(threadId, CONSTANT_VALUE);
  }

  @AfterEach
  void testCount() {
    System.out.println("Threads count: " + threads.size());
    System.out.println(threads.keySet());
    assertEquals(10, threads.size());
  }

}

Other examples:

• Junit5DynamicExtensionTest.java
• Junit5TimeoutCapableConcurrentTest.java
• Junit5CustomizeMethodInvocationTest.java

The demo project (demonstrates how to use the plugin):

• junit5-demo

Motivation

Junit5's ExecutionMode.CONCURRENT currently doesn't support running a test method multiple times, ideally, amount of parallel thread count.

We can of course configure parallel executions via junit-platform.properties. However, each test method is executed only once. Combining @RepeatedTest into it is also not a desired solution, each repetition independently triggers @BeforeEach, and @AfterEach phases making it harder to manage shared state between threads. Putting all the logic in a single method is indeed a solution but causes a lot of duplications.

Implementation Notes

Please notice that this extension is a workaround.

Since Junit5's invocation design does not allow to execute methods concurrently, we skip the original Junit's invocation by intention and execute the method manually in a separate thread pool. It might not work properly with the combination of other Junit extensions or annotations.

See the implementation details in ConcurrentExtension.java

Installation

Maven

<dependency>
  <groupId>dev.yavuztas</groupId>
  <artifactId>junit5-concurrent-extension</artifactId>
  <version>1.2</version>
  <scope>test</scope>
</dependency>

Gradle

testImplementation 'dev.yavuztas:junit5-concurrent-extension:1.2'

Java Version

This library supports Java version >= 8.