Test your components

In a previous tutorial we have created an input component for hazelcast. In this one we will show how to write some unit tests for it.

In this tutorial we will cover :

  1. How to load components in a unit test.

  2. How to create a job pipeline.

  3. How to run the test in standalone mode.

Here is our test class. let’s examine it in details.

public class HazelcastMapperTest {

    public static final SimpleComponentRule COMPONENTS = new SimpleComponentRule(HazelcastMapperTest.class
                                                                                    .getPackage().getName()); (1)

    private static HazelcastInstance instance; (2)

    public static void startInstanceWithData() { (3)
        instance = Hazelcast.newHazelcastInstance();
        final IMap<Object, Object> map = instance.getMap(HazelcastMapperTest.class.getSimpleName());
        IntStream.range(0, 100).forEach(i -> map.put("test_" + i, "value #" + i));

    public static void stopInstance() { (4)

    public void run() { (5)
        Job.components() (6)
                .component("source", "Hazelcast://Input?configuration.mapName=" + HazelcastMapperTest.class.getSimpleName())
                .component("output", "test://collector")

        final List<JsonObject> outputs = COMPONENTS.getCollectedData(JsonObject.class); (7)
        assertEquals(100, outputs.size());
1 SimpleComponentRule is a junit rule that let you load your component from a package. This rule also provide some tests components like emitter and collector Read more…​.
2 An embedded hazelcast instance that we will use to test our input component.
3 Here we create an embedded hazelcast instance and we fill it with some test data. We create a map with the name of our test class and add some data to it.
4 We clean up the instance after the end o the tests.
5 This is our unit test. Here we will create a job pipeline that use our input component.
6 We use the Job pipeline builder to create a job. It contains two components the input component and the test collector component. We connect the input component to the collector component, build the job and run it locally.
7 After the job has finished running. We simply use the COMPONENTS rule instance to get the collected data from the collector component. Then we can do some assertion on the collected data.
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