Skip test on Windows.

lib/io/event/selector/select.rb

@@ -175,9 +175,7 @@ def io_read(fiber, io, buffer, length, offset = 0)
 
 					Selector.nonblock(io) do
 						while true
-							Fiber.blocking{$stderr.puts "buffer.read(#{io}, 0, #{offset})"}
 							result = Fiber.blocking{buffer.read(io, 0, offset)}
-							Fiber.blocking{$stderr.puts "buffer.read(#{io}, 0, #{offset}) => #{result}"}
 
 							if result < 0
 								if again?(result)

test/io/event/selector/buffered_io.rb

@@ -17,6 +17,10 @@
 		let(:output) {pipe.last}
 
 		it "can read using a buffer" do
+			# Non-blocking pipes are probably not implemented in Ruby's compatibility layer.
+			# https://learn.microsoft.com/en-gb/windows/win32/api/namedpipeapi/nf-namedpipeapi-setnamedpipehandlestate?redirectedfrom=MSDN
+			skip "Not supported on Windows" if RUBY_PLATFORM =~ /mswin|mingw|cygwin/
+
 			writer = Fiber.new do
 				buffer = IO::Buffer.new(128)
 				expect(selector.io_write(Fiber.current, output, buffer, 128)).to be == 128
@@ -39,6 +43,8 @@
 		end
 
 		it "can read and write at the specified offset" do
+			skip "Not supported on Windows" if RUBY_PLATFORM =~ /mswin|mingw|cygwin/
+
 			writer = Fiber.new do
 				buffer = IO::Buffer.new(128)
 				expect(selector.io_write(Fiber.current, output, buffer, 128, 64)).to be == 64