Issue #9858: Add missing method stubs to _io.RawIOBase.  Patch by Laura Rupprecht.
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index f7c6e2d..af7da01 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -722,10 +722,10 @@
 @support.cpython_only
 class APIMismatchTest(unittest.TestCase):
 
-    @unittest.expectedFailure  # Test to be fixed by issue9858.
     def test_RawIOBase_io_in_pyio_match(self):
         """Test that pyio RawIOBase class has all c RawIOBase methods"""
-        mismatch = support.detect_api_mismatch(pyio.RawIOBase, io.RawIOBase)
+        mismatch = support.detect_api_mismatch(pyio.RawIOBase, io.RawIOBase,
+                                               ignore=('__weakref__',))
         self.assertEqual(mismatch, set(), msg='Python RawIOBase does not have all C RawIOBase methods')
 
     def test_RawIOBase_pyio_in_io_match(self):
diff --git a/Misc/ACKS b/Misc/ACKS
index 71fb0c5..807eeb2 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1212,6 +1212,7 @@
 Audun S. Runde
 Eran Rundstein
 Rauli Ruohonen
+Laura Rupprecht
 Jeff Rush
 Sam Rushing
 Mark Russell
diff --git a/Misc/NEWS b/Misc/NEWS
index ab12a65..fe83306 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -52,6 +52,9 @@
 Library
 -------
 
+- Issue #9858: Add missing method stubs to _io.RawIOBase.  Patch by Laura
+  Rupprecht.
+
 - Issue #22955: attrgetter, itemgetter and methodcaller objects in the operator
   module now support pickling.  Added readable and evaluable repr for these
   objects.  Based on patch by Josh Rosenberg.
diff --git a/Modules/_io/iobase.c b/Modules/_io/iobase.c
index 79d716a..025007e 100644
--- a/Modules/_io/iobase.c
+++ b/Modules/_io/iobase.c
@@ -952,9 +952,25 @@
     return result;
 }
 
+static PyObject *
+rawiobase_readinto(PyObject *self, PyObject *args)
+{
+    PyErr_SetNone(PyExc_NotImplementedError);
+    return NULL;
+}
+
+static PyObject *
+rawiobase_write(PyObject *self, PyObject *args)
+{
+    PyErr_SetNone(PyExc_NotImplementedError);
+    return NULL;
+}
+
 static PyMethodDef rawiobase_methods[] = {
     _IO__RAWIOBASE_READ_METHODDEF
     _IO__RAWIOBASE_READALL_METHODDEF
+    {"readinto", rawiobase_readinto, METH_VARARGS},
+    {"write", rawiobase_write, METH_VARARGS},
     {NULL, NULL}
 };