[NO ISSUE][TEST] Avoid NPE on empty result from cleanup query

Change-Id: Ic645b0f2c5ff29a6178cfd784fcbffb331386e90
Reviewed-on: https://asterix-gerrit.ics.uci.edu/2406
Sonar-Qube: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Contrib: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Integration-Tests: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: abdullah alamoudi <bamousaa@gmail.com>
diff --git a/asterixdb/asterix-app/src/test/java/org/apache/asterix/test/common/TestExecutor.java b/asterixdb/asterix-app/src/test/java/org/apache/asterix/test/common/TestExecutor.java
index bae1a21..b75df99 100644
--- a/asterixdb/asterix-app/src/test/java/org/apache/asterix/test/common/TestExecutor.java
+++ b/asterixdb/asterix-app/src/test/java/org/apache/asterix/test/common/TestExecutor.java
@@ -1649,14 +1649,18 @@
             InputStream resultStream = executeQueryService(
                     "select dv.DataverseName from Metadata.`Dataverse` as dv order by dv.DataverseName;",
                     getEndpoint(Servlets.QUERY_SERVICE), OutputFormat.CLEAN_JSON);
-            String out = IOUtils.toString(resultStream);
+            String out = IOUtils.toString(resultStream, StandardCharsets.UTF_8);
             ObjectMapper om = new ObjectMapper();
             om.setConfig(om.getDeserializationConfig().with(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT));
             JsonNode result;
             try {
                 result = om.readValue(out, ObjectNode.class).get("results");
             } catch (JsonMappingException e) {
-                result = om.createArrayNode();
+                LOGGER.warn("error mapping response '{}' to json", out, e);
+                result = null;
+            }
+            if (result == null) {
+                return;
             }
             for (int i = 0; i < result.size(); i++) {
                 JsonNode json = result.get(i);