fix #1398

scalaz · Jun 15, 2017 · f5cfd7b · f5cfd7b
1 parent f6f4d25
commit f5cfd7b
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Showing 2 changed files with 8 additions and 4 deletions.
diff --git a/core/src/main/scala/scalaz/Foldable.scala b/core/src/main/scala/scalaz/Foldable.scala
@@ -253,8 +253,8 @@ trait Foldable[F[_]]  { self =>
     } { 
       case (x @ ((amin, amax, bmin, bmax)), a) => 
         val b = f(a) 
-        if (Order[B].order(b, bmin) == LT) (a, amax, b, bmax)
-        else if (Order[B].order(b, bmax) == GT) (amin, a, bmin, b)
+        if (Order[B].lessThanOrEqual(b, bmin)) (a, amax, b, bmax)
+        else if (Order[B].greaterThanOrEqual(b, bmax)) (amin, a, bmin, b)
         else x
     } map {
       case (amin, amax, _, _) => (amin, amax)

diff --git a/tests/src/test/scala/scalaz/FoldableTest.scala b/tests/src/test/scala/scalaz/FoldableTest.scala
@@ -69,10 +69,14 @@ object FoldableTest extends SpecLite {
       (xs extremaOf f) must_== (xs minimumOf f).tuple(xs maximumOf f)
   }
   "extremaBy" ! forAll {
-    (xs: List[Int]) => 
-      val f: Int => Double = 1D + _
+    (xs: List[Int], f: Int => Int) =>
       (xs extremaBy f) must_== (xs minimumBy f).tuple(xs maximumBy f)
   }
+  "extremaBy consistent with minimumBy/maximumBy" ! {
+    val xs = (1 to 6).toList
+    val f: Int => Int = _ % 3
+    (xs extremaBy f) must_== (xs minimumBy f).tuple(xs maximumBy f)
+  }
 
   "distinct" ! forAll {
     (xs: List[Int]) =>