SI-8475 GroupedIterator is also lazy when padded

This is the related case which dnlgtm in the previous fix.

The old code seems to be tilting for laziness, but we have
to fill the buffer with the current group anyway, so there
is no reason to be coy about calling ArrayBuffer.length.

1 files changed, 8 insertions, 0 deletions

diff --git a/test/junit/scala/collection/IteratorTest.scala b/test/junit/scala/collection/IteratorTest.scala
index cb7cbb40bc..b7a9805c9f 100644
--- a/test/junit/scala/collection/IteratorTest.scala
+++ b/test/junit/scala/collection/IteratorTest.scala
@@ -17,4 +17,12 @@ class IteratorTest {
     slidingIt.next
     assertEquals("Counter should be one, that means we didn't look further than needed", 1, counter)
   }
+
+  @Test def groupedIteratorIsLazyWhenPadded(): Unit = {
+    var counter = 0
+    def it = new Iterator[Int] { var i = 0 ; def hasNext = { counter = i; true } ; def next = { i += 1; i } }
+    val slidingIt = it sliding 2 withPadding -1
+    slidingIt.next
+    assertEquals("Counter should be one, that means we didn't look further than needed", 1, counter)
+  }
 }