Add test for IO-like objects in IO.copy_stream. #4796

jruby · Apr 11, 2018 · cc93db8 · cc93db8
1 parent a512032
commit cc93db8
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diff --git a/core/src/main/java/org/jruby/util/io/FilenoUtil.java b/core/src/main/java/org/jruby/util/io/FilenoUtil.java
@@ -84,6 +84,7 @@ public void unregisterWrapper(int fileno) {
         filenoMap.remove(fileno);
     }
 
+    // Used by testing. See test/jruby/test_io.rb, test_io_copy_stream_does_not_leak_io_like_objects
     public int getNumberOfWrappers() {
         return filenoMap.size();
     }

diff --git a/test/jruby/test_io.rb b/test/jruby/test_io.rb
@@ -580,4 +580,32 @@ def test_stringio_gets_nil_separator_limit
     assert_equal 'ab', stringio.gets(nil, 2)
   end
 
+  # jruby/jruby#4796
+  def test_io_copy_stream_does_not_leak_io_like_objects
+    in_stream = Tempfile.new('4796')
+    in_stream.write('1234567890')
+    in_stream.rewind
+
+    out_stream = Object.new
+    def out_stream.write(stuff)
+      stuff.length
+    end
+    def out_stream.read(*n)
+      nil
+    end
+
+    fu = JRuby.runtime.fileno_util
+
+    before = fu.number_of_wrappers
+
+    100.times do
+      IO.copy_stream(in_stream, out_stream)
+      IO.copy_stream(out_stream, in_stream)
+    end
+
+    after = fu.number_of_wrappers
+
+    assert_equal before, after, "no wrappers should have been registered"
+  end
+
 end