From 77f2d51068d22b29e144e23a29c63c87466ddca0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jyri-Matti=20La=CC=88hteenma=CC=88ki?=
 <jyri-matti.lahteenmaki@solita.fi>
Date: Tue, 17 Sep 2024 15:45:41 +0300
Subject: [PATCH] whoops, intersection of iterable returned always empty set

---
 pom.xml                                               |  2 +-
 .../java/fi/solita/utils/functional/FunctionalS.java  |  2 +-
 .../fi/solita/utils/functional/FunctionalTest.java    | 11 +++++++++++
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/pom.xml b/pom.xml
index e74ea67..9460817 100644
--- a/pom.xml
+++ b/pom.xml
@@ -2,7 +2,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>fi.solita.utils</groupId>
     <artifactId>functional-utils</artifactId>
-    <version>0.12.53</version>
+    <version>0.12.54</version>
     <build>
         <resources>
                 <resource>
diff --git a/src/main/java/fi/solita/utils/functional/FunctionalS.java b/src/main/java/fi/solita/utils/functional/FunctionalS.java
index 823377f..db22f40 100644
--- a/src/main/java/fi/solita/utils/functional/FunctionalS.java
+++ b/src/main/java/fi/solita/utils/functional/FunctionalS.java
@@ -225,7 +225,7 @@ public static final <T> Set<T> intersection(Set<T> e1, Set<T> e2, Set<T> e3, Set
      * @return Set intersection of Sets in {@code es}.
      */
     public static final <T> Set<T> intersection(Iterable<? extends Set<T>> es) {
-        return FunctionalImpl.fold(Collections.<T>emptySet(), SemiGroups.<T>setIntersection(), es);
+        return FunctionalImpl.fold(SemiGroups.<T>setIntersection(), es).getOrElse(Collections.<T>emptySet());
     }
     
     
diff --git a/src/test/java/fi/solita/utils/functional/FunctionalTest.java b/src/test/java/fi/solita/utils/functional/FunctionalTest.java
index 997025d..d708369 100644
--- a/src/test/java/fi/solita/utils/functional/FunctionalTest.java
+++ b/src/test/java/fi/solita/utils/functional/FunctionalTest.java
@@ -1,5 +1,6 @@
 package fi.solita.utils.functional;
 import static fi.solita.utils.functional.Collections.emptyList;
+import static fi.solita.utils.functional.Collections.emptySet;
 import static fi.solita.utils.functional.Collections.newList;
 import static fi.solita.utils.functional.Collections.newMutableList;
 import static fi.solita.utils.functional.Collections.newSet;
@@ -412,4 +413,14 @@ public void padRight() {
         assertEquals("xx", Functional.padRight(2, '0', "xx").toString());
         assertEquals("xxx", Functional.padRight(2, '0', "xxx").toString());
     }
+    
+    @Test
+    public void testIntersection() {
+        assertEquals(emptySet(), Functional.intersection(Collections.<Integer>emptySet(), newSet(2,3)));
+        assertEquals(emptySet(), Functional.intersection(newSet(2,3), Collections.<Integer>emptySet()));
+        assertEquals(emptySet(), Functional.intersection(Arrays.asList(Collections.<Integer>emptySet(), newSet(2,3))));
+        
+        assertEquals(newSet(2), Functional.intersection(newSet(1,2), newSet(2,3)));
+        assertEquals(newSet(2), Functional.intersection(Arrays.asList(newSet(1,2), newSet(2,3))));
+    }
 }