Fix boundary in Enum.take/2, closes #3042

Signed-off-by: José Valim <[email protected]>

Author: José Valim

lib/elixir/lib/enum.ex

@@ -1738,10 +1738,10 @@ defmodule Enum do
   def take(collection, count) when count > 0 do
     {_, {res, _}} =
       Enumerable.reduce(collection, {:cont, {[], count}}, fn(entry, {list, count}) ->
-        if count > 1 do
-          {:cont, {[entry|list], count - 1}}
-        else
-          {:halt, {[entry|list], count}}
+        case count do
+          0 -> {:halt, {list, count}}
+          1 -> {:halt, {[entry|list], count - 1}}
+          _ -> {:cont, {[entry|list], count - 1}}
         end
       end)
     :lists.reverse(res)

lib/elixir/test/elixir/stream_test.exs

@@ -88,6 +88,8 @@ defmodule StreamTest do
            [[1], [2, 2], [3], [4, 4, 6], [7, 7]]
     assert stream |> Stream.take(3) |> Enum.to_list ==
            [[1], [2, 2], [3]]
+    assert 1..10 |> Stream.chunk(2) |> Enum.take(2) ==
+           [[1, 2], [3, 4]]
   end
 
   test "chunk_by/2 is zippable" do