Expand DocumentMapperTests (backport of #76368) (#76378)

Adds a test for setting the maximum number of dimensions setting and
tests the names and types of the metadata fields in the index.
Previously we just asserted the count of metadata fields. That made it
hard to read failures.

server/src/test/java/org/elasticsearch/index/mapper/DocumentMapperTests.java

@@ -23,13 +23,18 @@
 import org.elasticsearch.index.mapper.MapperService.MergeReason;
 
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.concurrent.CyclicBarrier;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
 
+import static io.github.nik9000.mapmatcher.ListMatcher.matchesList;
+import static io.github.nik9000.mapmatcher.MapMatcher.assertMap;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.notNullValue;
@@ -288,7 +293,35 @@ public void testEmptyDocumentMapper() {
         assertNotNull(documentMapper.idFieldMapper());
         assertNotNull(documentMapper.sourceMapper());
         assertNotNull(documentMapper.IndexFieldMapper());
-        assertEquals(10, documentMapper.mappers().getMapping().getMetadataMappersMap().size());
-        assertEquals(10, documentMapper.mappers().getMatchingFieldNames("*").size());
+        List<Class<?>> metadataMappers = new ArrayList<>(documentMapper.mappers().getMapping().getMetadataMappersMap().keySet());
+        Collections.sort(metadataMappers, Comparator.comparing(c -> c.getSimpleName()));
+        assertMap(
+            metadataMappers,
+            matchesList().item(DocCountFieldMapper.class)
+                .item(FieldNamesFieldMapper.class)
+                .item(IdFieldMapper.class)
+                .item(IgnoredFieldMapper.class)
+                .item(IndexFieldMapper.class)
+                .item(RoutingFieldMapper.class)
+                .item(SeqNoFieldMapper.class)
+                .item(SourceFieldMapper.class)
+                .item(TypeFieldMapper.class)
+                .item(VersionFieldMapper.class)
+        );
+        List<String> matching = new ArrayList<>(documentMapper.mappers().getMatchingFieldNames("*"));
+        Collections.sort(matching);
+        assertMap(
+            matching,
+            matchesList().item(DocCountFieldMapper.CONTENT_TYPE)
+                .item(FieldNamesFieldMapper.CONTENT_TYPE)
+                .item(IdFieldMapper.CONTENT_TYPE)
+                .item(IgnoredFieldMapper.CONTENT_TYPE)
+                .item(IndexFieldMapper.CONTENT_TYPE)
+                .item(RoutingFieldMapper.CONTENT_TYPE)
+                .item(SeqNoFieldMapper.CONTENT_TYPE)
+                .item(SourceFieldMapper.CONTENT_TYPE)
+                .item(TypeFieldMapper.NAME)
+                .item(VersionFieldMapper.CONTENT_TYPE)
+        );
     }
 }