diff -r e15c554cd43e Lib/doctest.py
--- a/Lib/doctest.py	Tue Jun 26 09:43:40 2012 +0200
+++ b/Lib/doctest.py	Tue Jul 03 09:09:17 2012 +0200
@@ -2695,6 +2695,11 @@
             """,
            }
 
+def _print_files_report(read, unread):
+    print('Test files read successfully: {0}'.format(read))
+    if unread:
+        print('Unreadable files: {0}'.format(unread))
+
 
 def _test():
     testfiles = [arg for arg in sys.argv[1:] if arg and arg[0] != '-']
@@ -2704,21 +2709,34 @@
             name, _ = os.path.splitext(name)
         print("usage: {0} [-v] file ...".format(name))
         return 2
+    read_files = 0
+    unread_files = 0
     for filename in testfiles:
-        if filename.endswith(".py"):
-            # It is a module -- insert its dir into sys.path and try to
-            # import it. If it is part of a package, that possibly
-            # won't work because of package imports.
-            dirname, filename = os.path.split(filename)
-            sys.path.insert(0, dirname)
-            m = __import__(filename[:-3])
-            del sys.path[0]
-            failures, _ = testmod(m)
+        try:
+            if filename.endswith(".py"):
+                # It is a module -- insert its dir into sys.path and try to
+                # import it. If it is part of a package, that possibly
+                # won't work because of package imports.
+                dirname, filename = os.path.split(filename)
+                sys.path.insert(0, dirname)
+                m = __import__(filename[:-3])
+                del sys.path[0]
+                failures, _ = testmod(m)
+            else:
+                failures, _ = testfile(filename, module_relative=False)
+            if failures:
+                _print_files_report(read_files, unread_files)
+                return 1
+        except IOError as e:
+            print("Cannot read '{0}': {1}".format(filename, e))
+            unread_files += 1
         else:
-            failures, _ = testfile(filename, module_relative=False)
-        if failures:
-            return 1
-    return 0
+            read_files += 1
+    if unread_files:
+        _print_files_report(read_files, unread_files)
+        return 3
+    else:
+        return 0
 
 
 if __name__ == "__main__":