FINERACT-2534: Add edge case test for mergeMapsOfLists with duplicate keys

Devi Pathak · Devi Pathak · commit cb2f6e61c6e1 · 2026-03-15T18:27:03.000+05:30
diff --git a/fineract-core/src/test/java/org/apache/fineract/util/StreamUtilTest.java b/fineract-core/src/test/java/org/apache/fineract/util/StreamUtilTest.java
@@ -60,4 +60,14 @@ void mergeMapsOfListsWithEmptyStream() {
 
         Assertions.assertTrue(merged.isEmpty());
     }
+
+    @Test
+    void mergeMapsOfListsWhenSameKeyAppearsInMultipleMaps() {
+        Map<String, List<Integer>> map1 = Map.of("a", List.of(1, 2));
+        Map<String, List<Integer>> map2 = Map.of("a", List.of(3, 4));
+
+        Map<String, List<Integer>> merged = Stream.of(map1, map2).collect(StreamUtil.mergeMapsOfLists());
+
+        Assertions.assertEquals(List.of(1, 2, 3, 4), merged.get("a"));
+    }
 }

Original file line number	Diff line number	Diff line change
`@@ -60,4 +60,14 @@ void mergeMapsOfListsWithEmptyStream() {`
`60`	`60`
`61`	`61`	`Assertions.assertTrue(merged.isEmpty());`
`62`	`62`	`}`
	`63`	`+`
	`64`	`+ @Test`
	`65`	`+ void mergeMapsOfListsWhenSameKeyAppearsInMultipleMaps() {`
	`66`	`+ Map<String, List<Integer>> map1 = Map.of("a", List.of(1, 2));`
	`67`	`+ Map<String, List<Integer>> map2 = Map.of("a", List.of(3, 4));`
	`68`	`+`
	`69`	`+ Map<String, List<Integer>> merged = Stream.of(map1, map2).collect(StreamUtil.mergeMapsOfLists());`
	`70`	`+`
	`71`	`+ Assertions.assertEquals(List.of(1, 2, 3, 4), merged.get("a"));`
	`72`	`+ }`
`63`	`73`	`}`