Package org.apache.flink.testutils.junit

Class SharedObjectsExtension

java.lang.Object

org.apache.flink.testutils.junit.SharedObjectsExtension

All Implemented Interfaces:

org.junit.jupiter.api.extension.AfterEachCallback, org.junit.jupiter.api.extension.BeforeEachCallback, org.junit.jupiter.api.extension.Extension

@NotThreadSafe
public class SharedObjectsExtension
extends Object
implements org.junit.jupiter.api.extension.BeforeEachCallback, org.junit.jupiter.api.extension.AfterEachCallback

This rule allows objects to be used both in the main test case as well as in UDFs by using serializable SharedReferences. Usage:

    @RegisterExtension
     public final SharedObjectsExtension sharedObjects = SharedObjectsExtension.create();

    @Test
     public void test() throws Exception {
         StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        SharedReference<Queue<Long>> listRef = sharedObjects.add(new ConcurrentLinkedQueue<>());
         int n = 10000;
         env.setParallelism(100);
         env.fromSequence(0, n).map(i -> listRef.get().add(i));
         env.execute();
         assertEquals(n + 1, listRef.get().size());
         assertEquals(
                 LongStream.rangeClosed(0, n).boxed().collect(Collectors.toList()),
                 listRef.get().stream().sorted().collect(Collectors.toList()));
     }
 

The main idea is that shared objects are bound to the scope of a test case instead of a class. That allows us to:

• Avoid all kinds of static fields in test classes that only exist since all fields in UDFs need to be serializable.
• Hopefully make it easier to reason about the test setup
• Facilitate to share more test building blocks across test classes.
• Fully allow tests to be rerun/run in parallel without worrying about static fields

Note that since the shared objects are accessed through multiple threads, they need to be thread-safe or accessed in a thread-safe manner.

Method Summary

Modifier and Type	Method	Description
<T> SharedReference<T>	add(T object)	Adds a new object to this SharedObjects.
void	afterEach(org.junit.jupiter.api.extension.ExtensionContext context)
void	beforeEach(org.junit.jupiter.api.extension.ExtensionContext context)
static SharedObjectsExtension	create()	Creates a new instance.
boolean	equals(Object o)
int	hashCode()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Method Detail

create

public static SharedObjectsExtension create()

Creates a new instance. Usually that should be done inside a JUnit test class as an instance-field annotated with Rule.

add

public <T> SharedReference<T> add(T object)

Adds a new object to this SharedObjects. Although not necessary, it is recommended to only access the object through the returned SharedReference.

beforeEach

public void beforeEach(org.junit.jupiter.api.extension.ExtensionContext context)
                throws Exception

Specified by:

beforeEach in interface org.junit.jupiter.api.extension.BeforeEachCallback

Throws:

Exception

afterEach

public void afterEach(org.junit.jupiter.api.extension.ExtensionContext context)
               throws Exception

Specified by:

afterEach in interface org.junit.jupiter.api.extension.AfterEachCallback

Throws:

Exception

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object