Add tests for timer and interval with infinity

Author: josevalim

lib/elixir/lib/stream.ex

@@ -107,6 +107,7 @@ defmodule Stream do
   @type index :: non_neg_integer
 
   @type default :: any
+  @type timer :: non_neg_integer | :infinity
 
   # Require Stream.Reducers and its callbacks
   require Stream.Reducers, as: R
@@ -505,8 +506,10 @@ defmodule Stream do
       [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
 
   """
-  @spec interval(non_neg_integer) :: Enumerable.t()
-  def interval(n) when is_integer(n) and n >= 0 do
+  @spec interval(timer()) :: Enumerable.t()
+  def interval(n)
+      when is_integer(n) and n >= 0
+      when n == :infinity do
     unfold(0, fn count ->
       Process.sleep(n)
       {count, count + 1}
@@ -787,8 +790,10 @@ defmodule Stream do
       [0]
 
   """
-  @spec timer(non_neg_integer) :: Enumerable.t()
-  def timer(n) when is_integer(n) and n >= 0 do
+  @spec timer(timer()) :: Enumerable.t()
+  def timer(n)
+      when is_integer(n) and n >= 0
+      when n == :infinity do
     take(interval(n), 1)
   end
 

lib/elixir/test/elixir/stream_test.exs

@@ -499,13 +499,17 @@ defmodule StreamTest do
 
   test "interval/1" do
     stream = Stream.interval(10)
-
     {time_us, value} = :timer.tc(fn -> Enum.take(stream, 5) end)
 
     assert value == [0, 1, 2, 3, 4]
     assert time_us >= 50000
   end
 
+  test "interval/1 with infinity" do
+    stream = Stream.interval(:infinity)
+    spawn(Stream, :run, [stream])
+  end
+
   test "into/2 and run/1" do
     Process.put(:stream_cont, [])
     Process.put(:stream_done, false)
@@ -1119,6 +1123,11 @@ defmodule StreamTest do
     assert time_us >= 5000
   end
 
+  test "timer/1 with infinity" do
+    stream = Stream.timer(:infinity)
+    spawn(Stream, :run, [stream])
+  end
+
   test "unfold/2" do
     stream = Stream.unfold(10, fn x -> if x > 0, do: {x, x - 1} end)
     assert Enum.take(stream, 5) == [10, 9, 8, 7, 6]