Fixed #27108 -- Displayed collectstatic's delete/overwrite warnings only if some…

Fixed #27108 -- Displayed collectstatic's delete/overwrite warnings only if some files exist in STATIC_ROOT.

django/contrib/staticfiles/management/commands/collectstatic.py

@@ -173,22 +173,28 @@ class Command(BaseCommand):
         if self.is_local_storage() and self.storage.location:
             destination_path = self.storage.location
             message.append(':\n\n    %s\n\n' % destination_path)
+            should_warn_user = (
+                self.storage.exists(destination_path) and
+                any(self.storage.listdir(destination_path))
+            )
         else:
             destination_path = None
             message.append('.\n\n')
+            # Destination files existence not checked; play it safe and warn.
+            should_warn_user = True
 
-        if self.clear:
-            message.append('This will DELETE ALL FILES in this location!\n')
-        else:
-            message.append('This will overwrite existing files!\n')
-
-        message.append(
-            'Are you sure you want to do this?\n\n'
-            "Type 'yes' to continue, or 'no' to cancel: "
-        )
+        if self.interactive and should_warn_user:
+            if self.clear:
+                message.append('This will DELETE ALL FILES in this location!\n')
+            else:
+                message.append('This will overwrite existing files!\n')
 
-        if self.interactive and input(''.join(message)) != 'yes':
-            raise CommandError("Collecting static files cancelled.")
+            message.append(
+                'Are you sure you want to do this?\n\n'
+                "Type 'yes' to continue, or 'no' to cancel: "
+            )
+            if input(''.join(message)) != 'yes':
+                raise CommandError("Collecting static files cancelled.")
 
         collected = self.collect()
         modified_count = len(collected['modified'])

tests/staticfiles_tests/test_management.py

@@ -179,6 +179,7 @@ class TestCollectionClear(CollectionTestCase):
 class TestInteractiveMessages(CollectionTestCase):
     overwrite_warning_msg = "This will overwrite existing files!"
     delete_warning_msg = "This will DELETE ALL FILES in this location!"
+    files_copied_msg = "static files copied"
 
     @staticmethod
     def mock_input(stdout):
@@ -209,6 +210,26 @@ class TestInteractiveMessages(CollectionTestCase):
         self.assertIn(self.overwrite_warning_msg, output)
         self.assertNotIn(self.delete_warning_msg, output)
 
+    def test_no_warning_when_staticdir_does_not_exist(self):
+        stdout = six.StringIO()
+        shutil.rmtree(six.text_type(settings.STATIC_ROOT))
+        call_command('collectstatic', interactive=True, stdout=stdout)
+        output = force_text(stdout.getvalue())
+        self.assertNotIn(self.overwrite_warning_msg, output)
+        self.assertNotIn(self.delete_warning_msg, output)
+        self.assertIn(self.files_copied_msg, output)
+
+    def test_no_warning_for_empty_staticdir(self):
+        stdout = six.StringIO()
+        static_dir = tempfile.mkdtemp(prefix='collectstatic_empty_staticdir_test')
+        with override_settings(STATIC_ROOT=static_dir):
+            call_command('collectstatic', interactive=True, stdout=stdout)
+        shutil.rmtree(six.text_type(static_dir))
+        output = force_text(stdout.getvalue())
+        self.assertNotIn(self.overwrite_warning_msg, output)
+        self.assertNotIn(self.delete_warning_msg, output)
+        self.assertIn(self.files_copied_msg, output)
+
 
 class TestCollectionExcludeNoDefaultIgnore(TestDefaults, CollectionTestCase):
     """