added debug logs for queue time tests

Author: rashtao

src/test/java/com/arangodb/ArangoDBTest.java

@@ -751,6 +751,14 @@ public void queueTime() throws InterruptedException, ExecutionException {
                     assertThat(values[i].timestamp, greaterThanOrEqualTo(values[i - 1].timestamp));
                 }
             }
+
+            if (avg < 0.0) {
+                System.err.println("avg < 0: " + avg);
+                System.err.println("got values:");
+                for (QueueTimeSample v : values) {
+                    System.err.println(v.value);
+                }
+            }
             assertThat(avg, is(greaterThan(0.0)));
         } else {
             assertThat(avg, is(0.0));

src/test/java/com/arangodb/internal/QueueTimeMetricsImplTest.java

@@ -43,6 +43,7 @@ private void testQueue(int size) {
         QueueTimeSample[] values = q.getValues();
         assertThat(values.length, is(Math.min(size, QSIZE)));
         assertThat(q.getAvg(), is(closeTo(getAvg(values), 1.0E-12)));
+        assertThat(q.getAvg(), is(greaterThanOrEqualTo(0.0)));
 
         for (int i = 0; i < values.length; i++) {
             assertThat(values[i], is(notNullValue()));