From 77e48ba993a83ffd6e821ab69a09ab0d11771338 Mon Sep 17 00:00:00 2001
From: "R. David Murray" <rdmurray@bitdance.com>
Date: Sun, 20 Dec 2009 16:46:06 +0000
Subject: [PATCH] Issue #7376: When called with no arguments doctest was
 running a self-test.  Because of a change to the way tracebacks are printed,
 this self-test was failing.  The test is run (and passes) during normal
 regression testing.  So instead of running the failing self-test this patch
 makes doctest emit a usage message.  This is better behavior anyway since
 passing in arguments is the real reason to run doctest as a command.

Bug discovery and initial patch by Florent Xicluna.
---
 Lib/doctest.py | 40 ++++++++++++++++++++++------------------
 Misc/NEWS      |  3 +++
 2 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/Lib/doctest.py b/Lib/doctest.py
index aeeb15d1d5..158e8b8731 100644
--- a/Lib/doctest.py
+++ b/Lib/doctest.py
@@ -2660,27 +2660,31 @@ __test__ = {"_TestClass": _TestClass,
             """,
            }
 
+
 def _test():
     testfiles = [arg for arg in sys.argv[1:] if arg and arg[0] != '-']
-    if testfiles:
-        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)
-            else:
-                failures, _ = testfile(filename, module_relative=False)
-            if failures:
-                return 1
-    else:
-        r = unittest.TextTestRunner()
-        r.run(DocTestSuite())
+    if not testfiles:
+        name = os.path.basename(sys.argv[0])
+        if '__loader__' in globals() and name.endswith('.py'):  # python -m
+            name, _ = os.path.splitext(name)
+        print("usage: {0} [-v] file ...".format(name))
+        return 2
+    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)
+        else:
+            failures, _ = testfile(filename, module_relative=False)
+        if failures:
+            return 1
     return 0
 
+
 if __name__ == "__main__":
     sys.exit(_test())
diff --git a/Misc/NEWS b/Misc/NEWS
index c5d2380f82..e9d1a51740 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -49,6 +49,9 @@ Library
 Tests
 -----
 
+- Issue #7376: instead of running a self-test (which was failing) when called
+  with no arguments, doctest.py now gives a usage message.
+
 - Issue #7396: fix regrtest -s, which was broken by the -j enhancement.
 
 - Issue #7498: test_multiprocessing now uses test_support.find_unused_port
-- 
2.40.0