Move test/scheduler -> test/fiber [Bug #16892][ruby-core:98366].

Merged: https://github.com/ruby/ruby/pull/3110

test/fiber/test_enumerator.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+require 'test/unit'
+require 'socket'
+require_relative 'scheduler'
+
+class TestSchedulerEnumerator < Test::Unit::TestCase
+  MESSAGE = "Hello World"
+
+  def test_read_characters
+    skip unless defined?(UNIXSocket)
+
+    i, o = UNIXSocket.pair
+    skip unless i.nonblock? && o.nonblock?
+
+    message = String.new
+
+    thread = Thread.new do
+      scheduler = Scheduler.new
+      Thread.current.scheduler = scheduler
+
+      e = i.to_enum(:each_char)
+
+      Fiber do
+        o.write("Hello World")
+        o.close
+      end
+
+      Fiber do
+        begin
+          while c = e.next
+            message << c
+          end
+        rescue StopIteration
+          # Ignore.
+        end
+
+        i.close
+      end
+    end
+
+    thread.join
+
+    assert_equal(MESSAGE, message)
+  end
+end