integration tests

The number of shards used for indices created during integration tests is randomized between 1 and 10 unless overwritten upon index creation via index settings. Rule of thumb is not to specify the number of shards unless needed, so that each test will use a different one all the time.

There are a couple of helper methods in ElasticsearchIntegrationTest, which will make your tests shorter and more concise.

The TestCluster class is the heart of the cluster functionality in a randomized test and allows you to configure a specific setting or replay certain types of outages to check, how your custom code reacts.

In order to execute any actions, you have to use a client. You can use the ElasticsearchIntegrationTest.client() method to get back a random client. This client can be a TransportClient or a NodeClient - and usually you do not need to care as long as the action gets executed. There are several more methods for client selection inside of the TestCluster class, which can be accessed using the ElasticsearchIntegrationTest.cluster() method.

By default the tests are run with unique cluster per test suite. Of course all indices and templates are deleted between each test. However, sometimes you need to start a new cluster for each test - for example, if you load a certain plugin, but you do not want to load it for every test.

You can use the @ClusterScope annotation at class level to configure this behaviour

@ClusterScope(scope=TEST, numNodes=1)
public class CustomSuggesterSearchTests extends ElasticsearchIntegrationTest {
  // ... tests go here
}

The above sample configures the test to use a new cluster for each test method. The default scope is SUITE (one cluster for all test methods in the test). The numNodes settings allows you to only start a certain number of nodes, which can speed up test execution, as starting a new node is a costly and time consuming operation and might not be needed for this test.

As elasticsearch is using JUnit 4, using the @Before and @After annotations is not a problem. However you should keep in mind, that this does not have any effect in your cluster setup, as the cluster is already up and running when those methods are run. So in case you want to configure settings - like loading a plugin on node startup - before the node is actually running, you should overwrite the nodeSettings() method from the ElasticsearchIntegrationTest class and change the cluster scope to SUITE.

@Override
protected Settings nodeSettings(int nodeOrdinal) {
  return ImmutableSettings.settingsBuilder()
           .put("plugin.types", CustomSuggesterPlugin.class.getName())
           .put(super.nodeSettings(nodeOrdinal)).build();
}