add table default impl of exist and create

Signed-off-by: Peng Huo <[email protected]>

core/src/main/java/org/opensearch/sql/storage/Table.java

@@ -18,15 +18,21 @@ public interface Table {
 
   /**
    * Check if current table exists.
+   *
    * @return true if exists, otherwise false
    */
-  boolean exists();
+  default boolean exists() {
+    throw new UnsupportedOperationException("Unsupported Operation");
+  }
 
   /**
    * Create table given table schema.
+   *
    * @param schema table schema
    */
-  void create(Map<String, ExprType> schema);
+  default void create(Map<String, ExprType> schema) {
+    throw new UnsupportedOperationException("Unsupported Operation");
+  }
 
   /**
    * Get the {@link ExprType} for each field in the table.

core/src/test/java/org/opensearch/sql/planner/physical/catalog/CatalogTableTest.java

@@ -8,6 +8,7 @@
 package org.opensearch.sql.planner.physical.catalog;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.util.HashMap;
@@ -46,4 +47,21 @@ void testImplement() {
     assertTrue(physicalPlan instanceof CatalogTableScan);
   }
 
+  // todo. temporary added for code coverage. remove if required.
+  @Test
+  void testExist() {
+    UnsupportedOperationException exception =
+        assertThrows(UnsupportedOperationException.class,
+            () -> new CatalogTable(catalogService).exists());
+    assertEquals("Unsupported Operation", exception.getMessage());
+  }
+
+  // todo. temporary added for code coverage. remove if required.
+  @Test
+  void testCreateTable() {
+    UnsupportedOperationException exception =
+        assertThrows(UnsupportedOperationException.class,
+            () -> new CatalogTable(catalogService).create(new HashMap<>()));
+    assertEquals("Unsupported Operation", exception.getMessage());
+  }
 }