More esql index resolution tests

x-pack/plugin/esql/src/internalClusterTest/java/org/elasticsearch/xpack/esql/plugin/IndexResolutionIT.java

@@ -105,11 +105,19 @@ public void testDoesNotResolveMissingIndex() {
     }
 
     public void testDoesNotResolveEmptyPattern() {
+        assertAcked(client().admin().indices().prepareCreate("data"));
+        indexRandom(true, "data", 1);
+
         expectThrows(
             VerificationException.class,
             containsString("Unknown index [index-*]"),
-            () -> run(syncEsqlQueryRequest().query("FROM index-*"))
+            () -> run(syncEsqlQueryRequest().query("FROM index-* METADATA _index"))
         );
+
+        try (var response = run(syncEsqlQueryRequest().query("FROM data,index-* METADATA _index"))) {
+            assertOk(response);
+            assertResultConcreteIndices(response, "data");
+        }
     }
 
     public void testDoesNotResolveClosedIndex() {

x-pack/plugin/esql/src/internalClusterTest/java/org/elasticsearch/xpack/esql/plugin/LookupIndexResolutionIT.java

@@ -0,0 +1,78 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+package org.elasticsearch.xpack.esql.plugin;
+
+import org.elasticsearch.cluster.metadata.IndexMetadata;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.index.IndexMode;
+import org.elasticsearch.index.IndexSettings;
+import org.elasticsearch.xpack.esql.VerificationException;
+import org.elasticsearch.xpack.esql.action.AbstractEsqlIntegTestCase;
+import org.elasticsearch.xpack.esql.action.EsqlQueryResponse;
+
+import java.util.Map;
+
+import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
+import static org.elasticsearch.xpack.esql.action.EsqlQueryRequest.syncEsqlQueryRequest;
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.equalTo;
+
+public class LookupIndexResolutionIT extends AbstractEsqlIntegTestCase {
+
+    public void testResolvesConcreteIndex() {
+        createMainIndex("index-1");
+        createLookupIndex("lookup");
+
+        try (var response = run(syncEsqlQueryRequest().query("FROM index-1 | LOOKUP JOIN lookup ON language_code"))) {
+            assertOk(response);
+        }
+    }
+
+    public void testResolvesAlias() {
+        createMainIndex("index-1");
+        createLookupIndex("lookup");
+        assertAcked(
+            client().admin().indices().prepareAliases(TEST_REQUEST_TIMEOUT, TEST_REQUEST_TIMEOUT).addAlias("lookup", "lookup-alias")
+        );
+
+        try (var response = run(syncEsqlQueryRequest().query("FROM index-1 | LOOKUP JOIN lookup-alias ON language_code"))) {
+            assertOk(response);
+        }
+    }
+
+    public void testDoesNotResolveMissingIndex() {
+        createMainIndex("index-1");
+
+        expectThrows(
+            VerificationException.class,
+            containsString("Unknown index [fake-lookup]"),
+            () -> run(syncEsqlQueryRequest().query("FROM index-1 | LOOKUP JOIN fake-lookup ON language_code"))
+        );
+    }
+
+    private static void assertOk(EsqlQueryResponse response) {
+        assertThat(response.isPartial(), equalTo(false));
+    }
+
+    private void createMainIndex(String name) {
+        assertAcked(client().admin().indices().prepareCreate(name));
+        indexRandom(true, false, prepareIndex(name).setSource(Map.of("id", randomIdentifier(), "language_code", 1)));
+    }
+
+    private void createLookupIndex(String name) {
+        assertAcked(
+            client().admin()
+                .indices()
+                .prepareCreate(name)
+                .setSettings(
+                    Settings.builder().put(IndexSettings.MODE.getKey(), IndexMode.LOOKUP).put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, 1)
+                )
+        );
+        indexRandom(true, false, prepareIndex(name).setSource(Map.of("language_code", 1, "language", "english")));
+    }
+}