1 files changed, 1 insertions, 0 deletions
diff --git a/test/io.rb b/test/io.rb
index 6e1bcb247..1b0a2d52e 100644
--- a/test/io.rb
+++ b/test/io.rb
@@ -401,6 +401,7 @@ assert('IO.popen with in option') do
       assert_equal "hello", IO.popen("cat", "r", in: r) { |i| i.read }
       assert_equal "", r.read
     end
+    assert_raise(ArgumentError) { IO.popen("hello", "r", in: Object.new) }
   rescue NotImplementedError => e
     skip e.message
   end