4 files changed, 219 insertions, 2 deletions

diff --git a/tests/admin_views/admin.py b/tests/admin_views/admin.py
index 69570a8062..64e0e23229 100644
--- a/tests/admin_views/admin.py
+++ b/tests/admin_views/admin.py
@@ -18,7 +18,12 @@ from django.utils.html import format_html
 from django.utils.safestring import mark_safe
 from django.views.decorators.common import no_append_slash
 
-from .forms import MediaActionForm
+from .forms import (
+    MediaActionForm,
+    SectionFormWithDynamicOptgroups,
+    SectionFormWithObjectOptgroups,
+    SectionFormWithOptgroups,
+)
 from .models import (
     Actor,
     AdminOrderedAdminMethod,
@@ -1345,6 +1350,32 @@ site2.register(Language)
 site7 = admin.AdminSite(name="admin7")
 site7.register(Article, ArticleAdmin2)
 site7.register(Section)
+
+
+# Admin for testing optgroup in popup response
+class SectionAdminWithOptgroups(admin.ModelAdmin):
+    form = SectionFormWithOptgroups
+
+
+class SectionAdminWithObjectOptgroups(admin.ModelAdmin):
+    form = SectionFormWithObjectOptgroups
+
+
+class SectionAdminWithDynamicOptgroups(admin.ModelAdmin):
+    form = SectionFormWithDynamicOptgroups
+
+
+site11 = admin.AdminSite(name="admin11")
+site11.register(Article, ArticleAdmin2)
+site11.register(Section, SectionAdminWithOptgroups)
+
+site12 = admin.AdminSite(name="admin12")
+site12.register(Article, ArticleAdmin2)
+site12.register(Section, SectionAdminWithObjectOptgroups)
+
+site13 = admin.AdminSite(name="admin13")
+site13.register(Article, ArticleAdmin2)
+site13.register(Section, SectionAdminWithDynamicOptgroups)
 site7.register(PrePopulatedPost, PrePopulatedPostReadOnlyAdmin)
 site7.register(
     Pizza,
diff --git a/tests/admin_views/forms.py b/tests/admin_views/forms.py
index 3a3566c10f..f15a5b3ac1 100644
--- a/tests/admin_views/forms.py
+++ b/tests/admin_views/forms.py
@@ -1,7 +1,10 @@
+from django import forms
 from django.contrib.admin.forms import AdminAuthenticationForm, AdminPasswordChangeForm
 from django.contrib.admin.helpers import ActionForm
 from django.core.exceptions import ValidationError
 
+from .models import Section
+
 
 class CustomAdminAuthenticationForm(AdminAuthenticationForm):
     class Media:
@@ -23,3 +26,63 @@ class CustomAdminPasswordChangeForm(AdminPasswordChangeForm):
 class MediaActionForm(ActionForm):
     class Media:
         js = ["path/to/media.js"]
+
+
+class SectionFormWithOptgroups(forms.ModelForm):
+    articles = forms.ChoiceField(
+        choices=[
+            ("Published", [("1", "Test Article")]),
+            ("Draft", [("2", "Other Article")]),
+        ],
+        required=False,
+    )
+
+    class Meta:
+        model = Section
+        fields = ["name", "articles"]
+
+
+class SectionFormWithObjectOptgroups(forms.ModelForm):
+    """Form with model instances as optgroup keys (tests str() conversion)."""
+
+    articles = forms.ChoiceField(required=False)
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        # Use Section instances as optgroup keys
+        sections = Section.objects.all()[:2]
+        if sections:
+            self.fields["articles"].choices = [
+                (sections[0], [("1", "Article 1")]),
+                (
+                    sections[1] if len(sections) > 1 else sections[0],
+                    [("2", "Article 2")],
+                ),
+            ]
+
+    class Meta:
+        model = Section
+        fields = ["name", "articles"]
+
+
+class SectionFormWithDynamicOptgroups(forms.ModelForm):
+    """
+    Form where the field with optgroups is added dynamically in __init__.
+    This tests that the implementation doesn't rely on accessing the
+    uninstantiated form class's _meta or fields, which wouldn't work here.
+    """
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        # Dynamically add a field with optgroups after instantiation.
+        self.fields["articles"] = forms.ChoiceField(
+            choices=[
+                ("Category A", [("1", "Item 1"), ("2", "Item 2")]),
+                ("Category B", [("3", "Item 3"), ("4", "Item 4")]),
+            ],
+            required=False,
+        )
+
+    class Meta:
+        model = Section
+        fields = ["name"]
diff --git a/tests/admin_views/tests.py b/tests/admin_views/tests.py
index f7eaad659e..3377a6d441 100644
--- a/tests/admin_views/tests.py
+++ b/tests/admin_views/tests.py
@@ -11,7 +11,7 @@ from django.contrib import admin
 from django.contrib.admin import AdminSite, ModelAdmin
 from django.contrib.admin.helpers import ACTION_CHECKBOX_NAME
 from django.contrib.admin.models import ADDITION, DELETION, LogEntry
-from django.contrib.admin.options import TO_FIELD_VAR
+from django.contrib.admin.options import SOURCE_MODEL_VAR, TO_FIELD_VAR
 from django.contrib.admin.templatetags.admin_urls import add_preserved_filters
 from django.contrib.admin.tests import AdminSeleniumTestCase
 from django.contrib.admin.utils import quote
@@ -468,6 +468,126 @@ class AdminViewBasicTest(AdminViewBasicTestCase):
         response = self.client.post(reverse("admin:admin_views_article_add"), post_data)
         self.assertContains(response, "title with a new\\nline")
 
+    def test_popup_add_POST_with_valid_source_model(self):
+        """
+        Popup add with a valid source_model returns a successful response.
+        """
+        post_data = {
+            IS_POPUP_VAR: "1",
+            SOURCE_MODEL_VAR: "admin_views.section",
+            "title": "Test Article",
+            "content": "some content",
+            "date_0": "2010-09-10",
+            "date_1": "14:55:39",
+        }
+        response = self.client.post(reverse("admin:admin_views_article_add"), post_data)
+        self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "data-popup-response")
+        messages = list(response.wsgi_request._messages)
+        self.assertEqual(len(messages), 0)
+
+    def test_popup_add_POST_with_optgroups(self):
+        """
+        Popup add with source_model containing optgroup choices includes
+        the optgroup in the response.
+        """
+        post_data = {
+            IS_POPUP_VAR: "1",
+            SOURCE_MODEL_VAR: "admin_views.section",
+            "title": "Test Article",
+            "content": "some content",
+            "date_0": "2010-09-10",
+            "date_1": "14:55:39",
+        }
+        response = self.client.post(
+            reverse("admin11:admin_views_article_add"), post_data
+        )
+        self.assertEqual(response.status_code, 200)
+        self.assertContains(response, ""optgroup": "Published"")
+
+    def test_popup_add_POST_without_optgroups(self):
+        """
+        Popup add where source_model form exists but doesn't have the field
+        should work without crashing.
+        """
+        post_data = {
+            IS_POPUP_VAR: "1",
+            SOURCE_MODEL_VAR: "admin_views.section",
+            "title": "Test Article 2",
+            "content": "some content",
+            "date_0": "2010-09-10",
+            "date_1": "14:55:39",
+        }
+        # Use regular admin (not admin11) where Section doesn't have optgroups.
+        response = self.client.post(reverse("admin:admin_views_article_add"), post_data)
+        self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "data-popup-response")
+        self.assertNotContains(response, ""optgroup"")
+
+    def test_popup_add_POST_with_object_optgroups(self):
+        """
+        Popup add with source_model containing optgroups where the optgroup
+        keys are model instances (not strings) still serialize to strings.
+        """
+        post_data = {
+            IS_POPUP_VAR: "1",
+            SOURCE_MODEL_VAR: "admin_views.section",
+            "title": "Article 1",
+            "content": "some content",
+            "date_0": "2010-09-10",
+            "date_1": "14:55:39",
+        }
+        response = self.client.post(
+            reverse("admin12:admin_views_article_add"), post_data
+        )
+        self.assertEqual(response.status_code, 200)
+        # Check that optgroup is in the response with str() of Section instance
+        # The form uses Section.objects.all()[:2] which includes cls.s1
+        # ("Test section") as the first optgroup key (HTML encoded).
+        self.assertContains(response, ""optgroup": "Test section"")
+
+    def test_popup_add_POST_with_dynamic_optgroups(self):
+        """
+        Popup add with source_model where optgroup field is added dynamically
+        in __init__. This ensures the implementation doesn't rely on accessing
+        the uninstantiated form class's _meta or fields, but instead properly
+        instantiates the form with get_form(request)() to access field info.
+        """
+        post_data = {
+            IS_POPUP_VAR: "1",
+            SOURCE_MODEL_VAR: "admin_views.section",
+            "title": "Item 1",
+            "content": "some content",
+            "date_0": "2010-09-10",
+            "date_1": "14:55:39",
+        }
+        response = self.client.post(
+            reverse("admin13:admin_views_article_add"), post_data
+        )
+        self.assertEqual(response.status_code, 200)
+        self.assertContains(response, ""optgroup": "Category A"")
+
+    def test_popup_add_POST_with_invalid_source_model(self):
+        """
+        Popup add with an invalid source_model (non-existent app/model)
+        shows an error message instead of crashing.
+        """
+        post_data = {
+            IS_POPUP_VAR: "1",
+            SOURCE_MODEL_VAR: "admin_views.nonexistent",
+            "title": "Test Article",
+            "content": "some content",
+            "date_0": "2010-09-10",
+            "date_1": "14:55:39",
+        }
+        response = self.client.post(reverse("admin:admin_views_article_add"), post_data)
+        self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "data-popup-response")
+        messages = list(response.wsgi_request._messages)
+        self.assertEqual(len(messages), 1)
+        self.assertIn("admin_views.nonexistent", str(messages[0]))
+        self.assertIn("could not be found", str(messages[0]))
+
     def test_basic_edit_POST(self):
         """
         A smoke test to ensure POST on edit_view works.
diff --git a/tests/admin_views/urls.py b/tests/admin_views/urls.py
index c1e673d811..3c43b8721d 100644
--- a/tests/admin_views/urls.py
+++ b/tests/admin_views/urls.py
@@ -32,6 +32,9 @@ urlpatterns = [
     ),
     path("test_admin/admin9/", admin.site9.urls),
     path("test_admin/admin10/", admin.site10.urls),
+    path("test_admin/admin11/", admin.site11.urls),
+    path("test_admin/admin12/", admin.site12.urls),
+    path("test_admin/admin13/", admin.site13.urls),
     path("test_admin/has_permission_admin/", custom_has_permission_admin.site.urls),
     path("test_admin/autocomplete_admin/", autocomplete_site.urls),
     # Shares the admin URL prefix.