#64: Fixed adding items to the immutable tree map

mperry · mperry · commit f762bf3fdd0e · 2014-12-16T23:46:37.000+10:00
diff --git a/core/src/main/java/fj/data/List.java b/core/src/main/java/fj/data/List.java
@@ -1333,10 +1333,9 @@ public final <B, C, D> TreeMap<B, D> groupBy(
     return this.foldLeft(map -> element -> {
           final B key = keyFunction.f(element);
           final C value = valueFunction.f(element);
-          map.set(key, map.get(key)
+          return map.set(key, map.get(key)
               .map(existing -> groupingAcc.f(value, existing))
               .orSome(groupingAcc.f(value, groupingIdentity)));
-          return map;
         }, TreeMap.<B, D>empty(keyOrd)
     );
   }
diff --git a/tests/src/test/scala/fj/data/CheckList.scala b/tests/src/test/scala/fj/data/CheckList.scala
@@ -180,7 +180,8 @@ object CheckList extends Properties("List") {
   property("groupBy") = forAll((a: List[Int]) => {
     val result = a.groupBy((x: Int) => (x % 2 == 0): lang.Boolean)
     result.get(true).forall((xs: List[Int]) => xs.forall((x: Int) => (x % 2 == 0): lang.Boolean): lang.Boolean) &&
-      result.get(false).forall((xs: List[Int]) => xs.forall((x: Int) => (x % 2 != 0): lang.Boolean): lang.Boolean)
+      result.get(false).forall((xs: List[Int]) => xs.forall((x: Int) => (x % 2 != 0): lang.Boolean): lang.Boolean) &&
+      a.map((x: Int) => (x % 2) == 0: lang.Boolean).nub().length() == result.size()
   })
 
   property("groupByMonoid") = forAll((a: List[Int]) => {
