diff -r 96e543ba96a4 Doc/library/test.rst
--- a/Doc/library/test.rst	Tue May 28 15:53:46 2013 +0300
+++ b/Doc/library/test.rst	Tue May 28 16:00:25 2013 +0300
@@ -362,19 +362,34 @@
       New optional arguments *filters* and *quiet*.
 
 
-.. function:: captured_stdout()
+.. function:: captured_stderr()
+              captured_stdout()
 
-   A context manager that runs the :keyword:`with` statement body using a
-   :class:`io.StringIO` object as sys.stdout.  That object can be retrieved
-   using the ``as`` clause of the :keyword:`with` statement.
+   A context managers that temporarily replaces the
+   :data:`sys.stderr` / :data:`sys.stdout` stream with :class:`io.StringIO` object.
 
    Example use::
 
-      with captured_stdout() as s:
-          print("hello")
+      with captured_stderr() as s:
+          print("hello", file=sys.stderr)
       assert s.getvalue() == "hello\n"
 
 
+.. function:: captured_stdin()
+
+   A context manager that temporarily replaces the :data:`sys.stdin` stream with
+   :class:`io.StringIO` object.
+
+   Example use::
+
+      with captured_stdin() as s:
+          s.write('hello\n')
+          s.seek(0)
+          # call test code that consumes from stdin
+          captured = input()
+      self.assertEqual(captured, "hello")
+
+
 .. function:: temp_cwd(name='tempcwd', quiet=False, path=None)
 
    A context manager that temporarily changes the current working
diff -r 96e543ba96a4 Lib/test/support.py
--- a/Lib/test/support.py	Tue May 28 15:53:46 2013 +0300
+++ b/Lib/test/support.py	Tue May 28 16:00:25 2013 +0300
@@ -1181,14 +1181,29 @@
 
        with captured_stdout() as s:
            print("hello")
-       self.assertEqual(s.getvalue(), "hello")
+       self.assertEqual(s.getvalue(), "hello\n")
     """
     return captured_output("stdout")
 
 def captured_stderr():
+    """Capture the output of sys.stderr:
+
+       with captured_stderr() as s:
+           print("hello", file=sys.stderr)
+       self.assertEqual(s.getvalue(), "hello\n")
+    """
     return captured_output("stderr")
 
 def captured_stdin():
+    """Capture the input to sys.stdin:
+
+       with captured_stdin() as s:
+           s.write('hello\n')
+           s.seek(0)
+           # call test code that consumes from stdin
+           captured = input()
+       self.assertEqual(captured, "hello")
+    """
     return captured_output("stdin")
 
 
diff -r 96e543ba96a4 Lib/test/test_support.py
--- a/Lib/test/test_support.py	Tue May 28 15:53:46 2013 +0300
+++ b/Lib/test/test_support.py	Tue May 28 16:00:25 2013 +0300
@@ -141,8 +141,11 @@
 
     def test_captured_stdin(self):
         with support.captured_stdin() as s:
-            print("hello", file=sys.stdin)
-        self.assertEqual(s.getvalue(), "hello\n")
+            s.write('hello\n')
+            s.seek(0)
+            # call test code that consumes from stdin
+            captured = input()
+        self.assertEqual(captured, "hello")
 
     def test_gc_collect(self):
         support.gc_collect()