add test

tests/tck/features/insert/insertVertexOnly.feature

@@ -0,0 +1,31 @@
+# Copyright (c) 2021 vesoft inc. All rights reserved.
+#
+# This source code is licensed under Apache 2.0 License.
+
+Feature: insert vertex without tag
+  Background: Background name
+    Given an empty graph
+    And create a space with following options:
+      | partition_num  | 9     |
+      | replica_factor | 1     |
+      | vid_type       | int64 |
+  Scenario: insert vertex only
+    Given having executed:
+      """
+      CREATE EDGE e();
+      """
+    And wait 6 seconds
+    When executing query:
+      """
+      INSERT VERTEX VALUES 1,2,3;
+      INSERT EDGE e() VALUES 1->2:(),2->3:();
+      """
+    Then the execution should be successful
+    When executing query:
+      """
+      GO 2 STEP FROM 1 OVER e yield e._dst AS dst;
+      """
+    Then the result should be, in any order:
+      | dst |
+      | 3   |
+    Then drop the used space