Fixed #23930 -- Added copies of captured_std* managers from CPython's test.support.

StringIO import was adapted for compatibility with Python 2.

django/test/utils.py

@@ -493,3 +493,51 @@ def extend_sys_path(*paths):
         yield
     finally:
         sys.path = _orig_sys_path
+
+
+@contextmanager
+def captured_output(stream_name):
+    """Return a context manager used by captured_stdout/stdin/stderr
+    that temporarily replaces the sys stream *stream_name* with a StringIO.
+
+    Note: This function and the following ``captured_std*`` are copied
+          from CPython's ``test.support`` module."""
+    orig_stdout = getattr(sys, stream_name)
+    setattr(sys, stream_name, six.StringIO())
+    try:
+        yield getattr(sys, stream_name)
+    finally:
+        setattr(sys, stream_name, orig_stdout)
+
+
+def captured_stdout():
+    """Capture the output of sys.stdout:
+
+       with captured_stdout() as stdout:
+           print("hello")
+       self.assertEqual(stdout.getvalue(), "hello\n")
+    """
+    return captured_output("stdout")
+
+
+def captured_stderr():
+    """Capture the output of sys.stderr:
+
+       with captured_stderr() as stderr:
+           print("hello", file=sys.stderr)
+       self.assertEqual(stderr.getvalue(), "hello\n")
+    """
+    return captured_output("stderr")
+
+
+def captured_stdin():
+    """Capture the input to sys.stdin:
+
+       with captured_stdin() as stdin:
+           stdin.write('hello\n')
+           stdin.seek(0)
+           # call test code that consumes from sys.stdin
+           captured = input()
+       self.assertEqual(captured, "hello")
+    """
+    return captured_output("stdin")

tests/bash_completion/tests.py

@@ -7,7 +7,7 @@ import unittest
 
 from django.apps import apps
 from django.core.management import ManagementUtility
-from django.utils.six import StringIO
+from django.test.utils import captured_stdout
 
 
 class BashCompletionTests(unittest.TestCase):
@@ -20,12 +20,8 @@ class BashCompletionTests(unittest.TestCase):
     def setUp(self):
         self.old_DJANGO_AUTO_COMPLETE = os.environ.get('DJANGO_AUTO_COMPLETE')
         os.environ['DJANGO_AUTO_COMPLETE'] = '1'
-        self.output = StringIO()
-        self.old_stdout = sys.stdout
-        sys.stdout = self.output
 
     def tearDown(self):
-        sys.stdout = self.old_stdout
         if self.old_DJANGO_AUTO_COMPLETE:
             os.environ['DJANGO_AUTO_COMPLETE'] = self.old_DJANGO_AUTO_COMPLETE
         else:
@@ -53,11 +49,12 @@ class BashCompletionTests(unittest.TestCase):
 
     def _run_autocomplete(self):
         util = ManagementUtility(argv=sys.argv)
-        try:
-            util.autocomplete()
-        except SystemExit:
-            pass
-        return self.output.getvalue().strip().split('\n')
+        with captured_stdout() as stdout:
+            try:
+                util.autocomplete()
+            except SystemExit:
+                pass
+        return stdout.getvalue().strip().split('\n')
 
     def test_django_admin_py(self):
         "django_admin.py will autocomplete option flags"

tests/contenttypes_tests/tests.py

@@ -1,8 +1,6 @@
 # -*- coding: utf-8 -*-
 from __future__ import unicode_literals
 
-import sys
-
 from django.apps.registry import Apps, apps
 from django.contrib.contenttypes.fields import (
     GenericForeignKey, GenericRelation
@@ -12,9 +10,8 @@ from django.contrib.contenttypes.models import ContentType
 from django.core import checks
 from django.db import connections, models, router
 from django.test import TestCase
-from django.test.utils import override_settings
+from django.test.utils import captured_stdout, override_settings
 from django.utils.encoding import force_str
-from django.utils.six import StringIO
 
 from .models import Author, Article, SchemeIncludedURL
 
@@ -369,11 +366,6 @@ class UpdateContentTypesTests(TestCase):
         self.before_count = ContentType.objects.count()
         ContentType.objects.create(name='fake', app_label='contenttypes_tests', model='Fake')
         self.app_config = apps.get_app_config('contenttypes_tests')
-        self.old_stdout = sys.stdout
-        sys.stdout = StringIO()
-
-    def tearDown(self):
-        sys.stdout = self.old_stdout
 
     def test_interactive_true(self):
         """
@@ -381,8 +373,9 @@ class UpdateContentTypesTests(TestCase):
         stale contenttypes.
         """
         management.input = lambda x: force_str("yes")
-        management.update_contenttypes(self.app_config)
-        self.assertIn("Deleting stale content type", sys.stdout.getvalue())
+        with captured_stdout() as stdout:
+            management.update_contenttypes(self.app_config)
+        self.assertIn("Deleting stale content type", stdout.getvalue())
         self.assertEqual(ContentType.objects.count(), self.before_count)
 
     def test_interactive_false(self):
@@ -390,8 +383,9 @@ class UpdateContentTypesTests(TestCase):
         non-interactive mode of update_contenttypes() shouldn't delete stale
         content types.
         """
-        management.update_contenttypes(self.app_config, interactive=False)
-        self.assertIn("Stale content types remain.", sys.stdout.getvalue())
+        with captured_stdout() as stdout:
+            management.update_contenttypes(self.app_config, interactive=False)
+        self.assertIn("Stale content types remain.", stdout.getvalue())
         self.assertEqual(ContentType.objects.count(), self.before_count + 1)
 
 

tests/i18n/test_compilation.py

@@ -3,7 +3,6 @@
 import os
 import shutil
 import stat
-import sys
 import unittest
 import gettext as gettext_module
 
@@ -11,6 +10,7 @@ from django.core.management import call_command, CommandError, execute_from_comm
 from django.core.management.utils import find_command
 from django.test import SimpleTestCase
 from django.test import override_settings
+from django.test.utils import captured_stderr, captured_stdout
 from django.utils import translation
 from django.utils.translation import ugettext
 from django.utils.encoding import force_text
@@ -145,15 +145,11 @@ class ExcludedLocaleCompilationTests(MessageCompilationTests):
         self.addCleanup(self._rmrf, os.path.join(self.test_dir, 'locale'))
 
     def test_command_help(self):
-        old_stdout, old_stderr = sys.stdout, sys.stderr
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        try:
+        with captured_stdout(), captured_stderr():
             # `call_command` bypasses the parser; by calling
             # `execute_from_command_line` with the help subcommand we
             # ensure that there are no issues with the parser itself.
             execute_from_command_line(['django-admin', 'help', 'compilemessages'])
-        finally:
-            sys.stdout, sys.stderr = old_stdout, old_stderr
 
     def test_one_locale_excluded(self):
         call_command('compilemessages', exclude=['it'], stdout=StringIO())

tests/i18n/test_extraction.py

@@ -5,7 +5,6 @@ import io
 import os
 import re
 import shutil
-import sys
 import time
 from unittest import SkipTest, skipUnless
 import warnings
@@ -16,6 +15,7 @@ from django.core.management import execute_from_command_line
 from django.core.management.utils import find_command
 from django.test import SimpleTestCase
 from django.test import override_settings
+from django.test.utils import captured_stderr, captured_stdout
 from django.utils.encoding import force_text
 from django.utils._os import upath
 from django.utils import six
@@ -632,15 +632,11 @@ class ExcludedLocaleExtractionTests(ExtractorTests):
         self.addCleanup(self._rmrf, os.path.join(self.test_dir, 'locale'))
 
     def test_command_help(self):
-        old_stdout, old_stderr = sys.stdout, sys.stderr
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        try:
+        with captured_stdout(), captured_stderr():
             # `call_command` bypasses the parser; by calling
             # `execute_from_command_line` with the help subcommand we
             # ensure that there are no issues with the parser itself.
             execute_from_command_line(['django-admin', 'help', 'makemessages'])
-        finally:
-            sys.stdout, sys.stderr = old_stdout, old_stderr
 
     def test_one_locale_excluded(self):
         management.call_command('makemessages', exclude=['it'], stdout=StringIO())

tests/servers/test_basehttp.py

@@ -1,10 +1,9 @@
-import sys
-
 from django.core.handlers.wsgi import WSGIRequest
 from django.core.servers.basehttp import WSGIRequestHandler
 from django.test import TestCase
 from django.test.client import RequestFactory
-from django.utils.six import BytesIO, StringIO
+from django.test.utils import captured_stderr
+from django.utils.six import BytesIO
 
 
 class WSGIRequestHandlerTestCase(TestCase):
@@ -14,14 +13,10 @@ class WSGIRequestHandlerTestCase(TestCase):
 
         handler = WSGIRequestHandler(request, '192.168.0.2', None)
 
-        _stderr = sys.stderr
-        sys.stderr = StringIO()
-        try:
+        with captured_stderr() as stderr:
             handler.log_message("GET %s %s", str('\x16\x03'), "4")
             self.assertIn(
                 "You're accessing the developement server over HTTPS, "
                 "but it only supports HTTP.",
-                sys.stderr.getvalue()
+                stderr.getvalue()
             )
-        finally:
-            sys.stderr = _stderr

tests/user_commands/tests.py

@@ -1,5 +1,4 @@
 import os
-import sys
 import warnings
 
 from django.db import connection
@@ -7,6 +6,7 @@ from django.core import management
 from django.core.management import BaseCommand, CommandError
 from django.core.management.utils import find_command, popen_wrapper
 from django.test import SimpleTestCase
+from django.test.utils import captured_stderr, captured_stdout
 from django.utils import translation
 from django.utils.deprecation import RemovedInDjango20Warning
 from django.utils.six import StringIO
@@ -42,14 +42,9 @@ class CommandTests(SimpleTestCase):
         """
         with self.assertRaises(CommandError):
             management.call_command('dance', example="raise")
-        old_stderr = sys.stderr
-        sys.stderr = err = StringIO()
-        try:
-            with self.assertRaises(SystemExit):
-                management.ManagementUtility(['manage.py', 'dance', '--example=raise']).execute()
-        finally:
-            sys.stderr = old_stderr
-        self.assertIn("CommandError", err.getvalue())
+        with captured_stderr() as stderr, self.assertRaises(SystemExit):
+            management.ManagementUtility(['manage.py', 'dance', '--example=raise']).execute()
+        self.assertIn("CommandError", stderr.getvalue())
 
     def test_default_en_us_locale_set(self):
         # Forces en_us when set to true
@@ -100,14 +95,9 @@ class CommandTests(SimpleTestCase):
         self.assertEqual(out.getvalue(), "All right, let's dance Rock'n'Roll.\n")
 
         # Simulate command line execution
-        old_stdout, old_stderr = sys.stdout, sys.stderr
-        sys.stdout, sys.stderr = StringIO(), StringIO()
-        try:
+        with captured_stdout() as stdout, captured_stderr():
             management.execute_from_command_line(['django-admin', 'optparse_cmd'])
-        finally:
-            output = sys.stdout.getvalue()
-            sys.stdout, sys.stderr = old_stdout, old_stderr
-        self.assertEqual(output, "All right, let's dance Rock'n'Roll.\n")
+        self.assertEqual(stdout.getvalue(), "All right, let's dance Rock'n'Roll.\n")
 
     def test_calling_a_command_with_only_empty_parameter_should_ends_gracefully(self):
         out = StringIO()