raise ArgumentError for invalid Enum.count_until

lib/elixir/lib/enum.ex

@@ -780,6 +780,10 @@ defmodule Enum do
     end
   end
 
+  def count_until(_enumerable, limit) do
+    raise ArgumentError, "expected limit to be greater than 0, got: #{limit}"
+  end
+
   @doc """
   Counts the elements in the enumerable for which `fun` returns a truthy value, stopping at `limit`.
 
@@ -801,6 +805,10 @@ defmodule Enum do
     end
   end
 
+  def count_until(_enumerable, _fun, limit) do
+    raise ArgumentError, "expected limit to be greater than 0, got: #{limit}"
+  end
+
   @doc """
   Enumerates the `enumerable`, returning a list where all consecutive
   duplicate elements are collapsed to a single element.

lib/elixir/test/elixir/enum_test.exs

@@ -225,6 +225,16 @@ defmodule EnumTest do
     assert count_until_stream.([1, 2], 2) == 2
   end
 
+  test "count_until/2 with invalid limit" do
+    assert_raise ArgumentError, "expected limit to be greater than 0, got: 0", fn ->
+      Enum.count_until([1, 2, 3], 0)
+    end
+
+    assert_raise ArgumentError, "expected limit to be greater than 0, got: -22", fn ->
+      Enum.count_until([1, 2, 3], -22)
+    end
+  end
+
   test "count_until/3" do
     assert Enum.count_until([1, 2, 3, 4, 5, 6], fn x -> rem(x, 2) == 0 end, 2) == 2
     assert Enum.count_until([1, 2], fn x -> rem(x, 2) == 0 end, 2) == 1
@@ -243,6 +253,16 @@ defmodule EnumTest do
     assert count_until_stream.([], fn x -> rem(x, 2) == 0 end, 2) == 0
   end
 
+  test "count_until/3 with invalid limit" do
+    assert_raise ArgumentError, "expected limit to be greater than 0, got: 0", fn ->
+      Enum.count_until([1, 2, 3], fn x -> rem(x, 2) == 0 end, 0)
+    end
+
+    assert_raise ArgumentError, "expected limit to be greater than 0, got: -22", fn ->
+      Enum.count_until([1, 2, 3], fn x -> rem(x, 2) == 0 end, -22)
+    end
+  end
+
   test "dedup/1" do
     assert Enum.dedup([1, 1, 2, 1, 1, 2, 1]) == [1, 2, 1, 2, 1]
     assert Enum.dedup([2, 1, 1, 2, 1]) == [2, 1, 2, 1]