add IT for both

Signed-off-by: Jialiang Liang <jiallian@amazon.com>

Author: RyanL1997

integ-test/src/test/java/org/opensearch/sql/ppl/PPLPluginIT.java

@@ -96,6 +96,17 @@ public void sqlEnableSettingsTest() throws IOException {
     updateClusterSettings(new ClusterSetting(PERSISTENT, "plugins.ppl.enabled", null));
   }
 
+  @Test
+  public void testQueryEndpointShouldFailWithInvalidPayload() throws IOException {
+    exceptionRule.expect(ResponseException.class);
+    exceptionRule.expect(hasProperty("response", statusCode(400)));
+
+    Request post = new Request("POST", "/_plugins/_ppl");
+    post.setJsonEntity("{ \"query\": [\"search source=test\"] }");
+
+    client().performRequest(post);
+  }
+
   protected Request makePPLRequest(String query) {
     Request post = new Request("POST", "/_plugins/_ppl");
     post.setJsonEntity(String.format(Locale.ROOT, "{\n" + "  \"query\": \"%s\"\n" + "}", query));

integ-test/src/test/java/org/opensearch/sql/sql/QueryValidationIT.java

@@ -82,6 +82,27 @@ public void aggregationFunctionInSelectGroupByMultipleFields() throws IOExceptio
             "SELECT SUM(age) FROM opensearch-sql_test_index_account GROUP BY state.keyword");
   }
 
+  @Test
+  public void testSqlQueryWithArrayPayloadShouldFailWithBadRequest() throws IOException {
+    expectResponseException()
+        .hasStatusCode(BAD_REQUEST)
+        .hasErrorType("IllegalArgumentException")
+        .containsMessage("Failed to parse request payload");
+
+    whenExecuteMalformedPayload();
+  }
+
+  private static void whenExecuteMalformedPayload() throws IOException {
+    Request request = new Request("POST", QUERY_API_ENDPOINT);
+    request.setJsonEntity("{ \"query\": [\"SELECT * FROM opensearch-sql_test_index_account\"] }");
+
+    RequestOptions.Builder restOptionsBuilder = RequestOptions.DEFAULT.toBuilder();
+    restOptionsBuilder.addHeader("Content-Type", "application/json");
+    request.setOptions(restOptionsBuilder);
+
+    client().performRequest(request);
+  }
+
   public ResponseExceptionAssertion expectResponseException() {
     return new ResponseExceptionAssertion(exceptionRule);
   }