Fixed #27438 -- Added the diffsettings --default option.

4 files changed, 35 insertions, 3 deletions

diff --git a/django/core/management/commands/diffsettings.py b/django/core/management/commands/diffsettings.py
index 7bae48c218..3a5ebcf845 100644
--- a/django/core/management/commands/diffsettings.py
+++ b/django/core/management/commands/diffsettings.py
@@ -18,16 +18,24 @@ class Command(BaseCommand):
             '--all', action='store_true', dest='all', default=False,
             help='Display all settings, regardless of their value. Default values are prefixed by "###".',
         )
+        parser.add_argument(
+            '--default', dest='default', metavar='MODULE', default=None,
+            help=(
+                "The settings module to compare the current settings against. Leave empty to "
+                "compare against Django's default settings."
+            ),
+        )
 
     def handle(self, **options):
         # Inspired by Postfix's "postconf -n".
-        from django.conf import settings, global_settings
+        from django.conf import settings, Settings, global_settings
 
         # Because settings are imported lazily, we need to explicitly load them.
         settings._setup()
 
         user_settings = module_to_dict(settings._wrapped)
-        default_settings = module_to_dict(global_settings)
+        default = options['default']
+        default_settings = module_to_dict(Settings(default) if default else global_settings)
 
         output = []
         for key in sorted(user_settings):
diff --git a/docs/ref/django-admin.txt b/docs/ref/django-admin.txt
index 86b5e724fa..c35e728f26 100644
--- a/docs/ref/django-admin.txt
+++ b/docs/ref/django-admin.txt
@@ -223,7 +223,7 @@ Specifies the database onto which to open a shell. Defaults to ``default``.
 .. django-admin:: diffsettings
 
 Displays differences between the current settings file and Django's default
-settings.
+settings (or another settings file specified by :option:`--default`).
 
 Settings that don't appear in the defaults are followed by ``"###"``. For
 example, the default settings don't define :setting:`ROOT_URLCONF`, so
@@ -235,6 +235,13 @@ example, the default settings don't define :setting:`ROOT_URLCONF`, so
 Displays all settings, even if they have Django's default value. Such settings
 are prefixed by ``"###"``.
 
+.. django-admin-option:: --default MODULE
+
+.. versionadded:: 1.11
+
+The settings module to compare the current settings against. Leave empty to
+compare against Django's default settings.
+
 ``dumpdata``
 ------------
 
diff --git a/docs/releases/1.11.txt b/docs/releases/1.11.txt
index bbe1d63028..a612cb0e12 100644
--- a/docs/releases/1.11.txt
+++ b/docs/releases/1.11.txt
@@ -281,6 +281,9 @@ Management Commands
 * The new :option:`loaddata --exclude` option allows excluding models and apps
   while loading data from fixtures.
 
+* The new :option:`diffsettings --default` option allows specifying a settings
+  module other than Django's default settings to compare against.
+
 Migrations
 ~~~~~~~~~~
 
diff --git a/tests/admin_scripts/tests.py b/tests/admin_scripts/tests.py
index 84b44931b3..329263db0a 100644
--- a/tests/admin_scripts/tests.py
+++ b/tests/admin_scripts/tests.py
@@ -2128,6 +2128,20 @@ class DiffSettings(AdminScriptTestCase):
         self.assertNoOutput(err)
         self.assertOutput(out, "### STATIC_URL = None")
 
+    def test_custom_default(self):
+        """
+        The --default option specifies an alternate settings module for
+        comparison.
+        """
+        self.write_settings('settings_default.py', sdict={'FOO': '"foo"', 'BAR': '"bar1"'})
+        self.addCleanup(self.remove_settings, 'settings_default.py')
+        self.write_settings('settings_to_diff.py', sdict={'FOO': '"foo"', 'BAR': '"bar2"'})
+        self.addCleanup(self.remove_settings, 'settings_to_diff.py')
+        out, err = self.run_manage(['diffsettings', '--settings=settings_to_diff', '--default=settings_default'])
+        self.assertNoOutput(err)
+        self.assertNotInOutput(out, "FOO")
+        self.assertOutput(out, "BAR = 'bar2'")
+
 
 class Dumpdata(AdminScriptTestCase):
     """Tests for dumpdata management command."""