Add restart node enrich tests. (#43579)

This test verifies that enrich policies still exist after a full
cluster restart. If EnrichPolicy is not registered as named xcontent
in EnrichPlugin class then this test fails.

x-pack/plugin/enrich/src/test/java/org/elasticsearch/xpack/enrich/EnrichMultiNodeIT.java

@@ -46,11 +46,11 @@ import static org.hamcrest.Matchers.notNullValue;
 @ESIntegTestCase.ClusterScope(scope = ESIntegTestCase.Scope.TEST, numDataNodes = 0, numClientNodes = 0)
 public class EnrichMultiNodeIT extends ESIntegTestCase {
 
-    private static final String POLICY_NAME = "my-policy";
+    static final String POLICY_NAME = "my-policy";
     private static final String PIPELINE_NAME = "my-pipeline";
-    private static final String SOURCE_INDEX_NAME = "users";
+    static final String SOURCE_INDEX_NAME = "users";
-    private static final String KEY_FIELD = "email";
+    static final String KEY_FIELD = "email";
-    private static final String[] DECORATE_FIELDS = new String[]{"address", "city", "country"};
+    static final String[] DECORATE_FIELDS = new String[]{"address", "city", "country"};
 
     @Override
     protected Collection<Class<? extends Plugin>> nodePlugins() {

x-pack/plugin/enrich/src/test/java/org/elasticsearch/xpack/enrich/EnrichRestartIT.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.enrich;
+
+import org.elasticsearch.index.reindex.ReindexPlugin;
+import org.elasticsearch.plugins.Plugin;
+import org.elasticsearch.test.ESIntegTestCase;
+import org.elasticsearch.xpack.core.enrich.EnrichPolicy;
+import org.elasticsearch.xpack.core.enrich.action.ListEnrichPolicyAction;
+import org.elasticsearch.xpack.core.enrich.action.PutEnrichPolicyAction;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Optional;
+
+import static org.elasticsearch.xpack.enrich.EnrichMultiNodeIT.DECORATE_FIELDS;
+import static org.elasticsearch.xpack.enrich.EnrichMultiNodeIT.KEY_FIELD;
+import static org.elasticsearch.xpack.enrich.EnrichMultiNodeIT.POLICY_NAME;
+import static org.elasticsearch.xpack.enrich.EnrichMultiNodeIT.SOURCE_INDEX_NAME;
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.is;
+
+@ESIntegTestCase.ClusterScope(scope = ESIntegTestCase.Scope.TEST, numDataNodes = 0, numClientNodes = 0)
+public class EnrichRestartIT extends ESIntegTestCase {
+
+    @Override
+    protected Collection<Class<? extends Plugin>> nodePlugins() {
+        return Arrays.asList(EnrichPlugin.class, ReindexPlugin.class);
+    }
+
+    @Override
+    protected Collection<Class<? extends Plugin>> transportClientPlugins() {
+        return nodePlugins();
+    }
+
+    public void testRestart() throws Exception {
+        final int numPolicies = randomIntBetween(2, 4);
+        internalCluster().startNode();
+
+        EnrichPolicy enrichPolicy = new EnrichPolicy(EnrichPolicy.EXACT_MATCH_TYPE, null,
+            Collections.singletonList(SOURCE_INDEX_NAME), KEY_FIELD, Arrays.asList(DECORATE_FIELDS));
+        for (int i = 0; i < numPolicies; i++) {
+            String policyName = POLICY_NAME + i;
+            PutEnrichPolicyAction.Request request = new PutEnrichPolicyAction.Request(policyName, enrichPolicy);
+            client().execute(PutEnrichPolicyAction.INSTANCE, request).actionGet();
+        }
+
+        verifyPolicies(numPolicies, enrichPolicy);
+        // After full restart the policies should still exist:
+        internalCluster().fullRestart();
+        verifyPolicies(numPolicies, enrichPolicy);
+    }
+
+    private static void verifyPolicies(int numPolicies, EnrichPolicy enrichPolicy) {
+        ListEnrichPolicyAction.Response response =
+            client().execute(ListEnrichPolicyAction.INSTANCE, new ListEnrichPolicyAction.Request()).actionGet();
+        assertThat(response.getPolicies().size(), equalTo(numPolicies));
+        for (int i = 0; i < numPolicies; i++) {
+            String policyName = POLICY_NAME + i;
+            Optional<EnrichPolicy.NamedPolicy> result = response.getPolicies().stream()
+                .filter(namedPolicy -> namedPolicy.getName().equals(policyName))
+                .findFirst();
+            assertThat(result.isPresent(), is(true));
+            assertThat(result.get().getPolicy(), equalTo(enrichPolicy));
+        }
+    }
+
+}