1 files changed, 20 insertions, 0 deletions
diff --git a/test/ruby/test_io.rb b/test/ruby/test_io.rb
index 642c8f4430..19b4f0ebf6 100644
--- a/test/ruby/test_io.rb
+++ b/test/ruby/test_io.rb
@@ -1,6 +1,15 @@
 require 'test/unit'
+require 'tmpdir'
 
 class TestIO < Test::Unit::TestCase
+  def mkcdtmpdir
+    Dir.mktmpdir {|d|
+      Dir.chdir(d) {
+        yield
+      }
+    }
+  end
+
   def test_gets_rs
     r, w = IO.pipe
     w.print "\377xyz"
@@ -8,4 +17,15 @@ class TestIO < Test::Unit::TestCase
     assert_equal("\377", r.gets("\377"), "[ruby-dev:24460]")
     r.close
   end
+
+  def test_readpartial_pos
+    mkcdtmpdir {
+      open("foo", "w") {|f| f << "abc" }
+      open("foo") {|f|
+        f.seek(0)
+        assert_equal("ab", f.readpartial(2))
+        assert_equal(2, f.pos)
+      }
+    }
+  end
 end