add missing asserts, increase code coverage

Signed-off-by: Sandesh Kumar <sandeshkr419@gmail.com>

Author: sandeshkr419

server/src/main/java/org/opensearch/search/aggregations/bucket/range/RangeAggregator.java

@@ -547,6 +547,9 @@ private void computeMatchingRange(RangeAggregator.Range[] ranges, int lowBound,
                 }
             }
 
+            assert startLo == lowBound || value >= maxTo[startLo - 1];
+            assert endHi == ranges.length - 1 || value < ranges[endHi + 1].from;
+
             this.startLo = startLo;
             this.endHi = endHi;
         }

server/src/test/java/org/opensearch/search/SearchServiceStarTreeTests.java

@@ -727,6 +727,7 @@ public void testQueryParsingForRangeAggregations() throws IOException {
         );
         String KEYWORD_FIELD = "clientip";
         String NUMERIC_FIELD = "size";
+        String NUMERIC_FIELD_NOT_ORDERED_DIMENSION = "rank";
 
         MaxAggregationBuilder maxAggNoSub = max("max").field(FIELD_NAME);
         SumAggregationBuilder sumAggSub = sum("sum").field(FIELD_NAME).subAggregation(maxAggNoSub);
@@ -794,6 +795,12 @@ public void testQueryParsingForRangeAggregations() throws IOException {
         sourceBuilder = new SearchSourceBuilder().size(0).query(new TermQueryBuilder(FIELD_NAME, 1)).aggregation(rangeAggregationBuilder);
         assertStarTreeContext(request, sourceBuilder, null, -1);
 
+        // Case 5: Range Aggregation on field not in ordered dimensions, should not use star tree
+        rangeAggregationBuilder = range("range").field(NUMERIC_FIELD_NOT_ORDERED_DIMENSION).addRange(0, 100).subAggregation(medianAgg);
+        baseQuery = new MatchAllQueryBuilder();
+        sourceBuilder = new SearchSourceBuilder().size(0).query(baseQuery).aggregation(rangeAggregationBuilder);
+        assertStarTreeContext(request, sourceBuilder, null, -1);
+
         setStarTreeIndexSetting(null);
     }
 

server/src/test/java/org/opensearch/search/aggregations/startree/NumericTermsAggregatorTests.java

@@ -323,6 +323,9 @@ public static XContentBuilder getExpandedMapping(int maxLeafDocs, boolean skipSt
             b.startObject("size");
             b.field("type", "float");
             b.endObject();
+            b.startObject("rank");
+            b.field("type", "integer");
+            b.endObject();
             b.startObject("geoip");
             b.startObject("properties");
             b.startObject("country_name");