Fixed #9602 -- Added AdminSite.get_model_admin().

This allows retrieving an admin class for the given model class without
using internal attributes.

7 files changed, 46 insertions, 29 deletions

diff --git a/tests/admin_changelist/tests.py b/tests/admin_changelist/tests.py
index 176b49c66c..8fdd343b18 100644
--- a/tests/admin_changelist/tests.py
+++ b/tests/admin_changelist/tests.py
@@ -878,7 +878,7 @@ class ChangeListTests(TestCase):
         user_parents = self._create_superuser("parents")
 
         # Test with user 'noparents'
-        m = custom_site._registry[Child]
+        m = custom_site.get_model_admin(Child)
         request = self._mocked_authenticated_request("/child/", user_noparents)
         response = m.changelist_view(request)
         self.assertNotContains(response, "Parent object")
@@ -903,7 +903,7 @@ class ChangeListTests(TestCase):
 
         # Test default implementation
         custom_site.register(Child, ChildAdmin)
-        m = custom_site._registry[Child]
+        m = custom_site.get_model_admin(Child)
         request = self._mocked_authenticated_request("/child/", user_noparents)
         response = m.changelist_view(request)
         self.assertContains(response, "Parent object")
diff --git a/tests/admin_checks/tests.py b/tests/admin_checks/tests.py
index 417c8504ed..d2d1eb219e 100644
--- a/tests/admin_checks/tests.py
+++ b/tests/admin_checks/tests.py
@@ -276,8 +276,7 @@ class SystemChecksTestCase(SimpleTestCase):
         class MyBookAdmin(admin.ModelAdmin):
             def check(self, **kwargs):
                 errors = super().check(**kwargs)
-                author_admin = self.admin_site._registry.get(Author)
-                if author_admin is None:
+                if not self.admin_site.is_registered(Author):
                     errors.append("AuthorAdmin missing!")
                 return errors
 
diff --git a/tests/admin_ordering/tests.py b/tests/admin_ordering/tests.py
index 486e222d01..57f8fc7c6f 100644
--- a/tests/admin_ordering/tests.py
+++ b/tests/admin_ordering/tests.py
@@ -152,10 +152,10 @@ class TestRelatedFieldsAdminOrdering(TestCase):
             site.unregister(Band)
 
     def check_ordering_of_field_choices(self, correct_ordering):
-        fk_field = site._registry[Song].formfield_for_foreignkey(
+        fk_field = site.get_model_admin(Song).formfield_for_foreignkey(
             Song.band.field, request=None
         )
-        m2m_field = site._registry[Song].formfield_for_manytomany(
+        m2m_field = site.get_model_admin(Song).formfield_for_manytomany(
             Song.other_interpreters.field, request=None
         )
         self.assertEqual(list(fk_field.queryset), correct_ordering)
diff --git a/tests/admin_registration/tests.py b/tests/admin_registration/tests.py
index 25f317d322..c8caf3f202 100644
--- a/tests/admin_registration/tests.py
+++ b/tests/admin_registration/tests.py
@@ -22,13 +22,13 @@ class TestRegistration(SimpleTestCase):
 
     def test_bare_registration(self):
         self.site.register(Person)
-        self.assertIsInstance(self.site._registry[Person], admin.ModelAdmin)
+        self.assertIsInstance(self.site.get_model_admin(Person), admin.ModelAdmin)
         self.site.unregister(Person)
         self.assertEqual(self.site._registry, {})
 
     def test_registration_with_model_admin(self):
         self.site.register(Person, NameAdmin)
-        self.assertIsInstance(self.site._registry[Person], NameAdmin)
+        self.assertIsInstance(self.site.get_model_admin(Person), NameAdmin)
         self.site.unregister(Person)
         self.assertEqual(self.site._registry, {})
 
@@ -57,22 +57,28 @@ class TestRegistration(SimpleTestCase):
 
     def test_registration_with_star_star_options(self):
         self.site.register(Person, search_fields=["name"])
-        self.assertEqual(self.site._registry[Person].search_fields, ["name"])
+        self.assertEqual(self.site.get_model_admin(Person).search_fields, ["name"])
+
+    def test_get_model_admin_unregister_model(self):
+        msg = "The model Person is not registered."
+        with self.assertRaisesMessage(admin.sites.NotRegistered, msg):
+            self.site.get_model_admin(Person)
 
     def test_star_star_overrides(self):
         self.site.register(
             Person, NameAdmin, search_fields=["name"], list_display=["__str__"]
         )
-        self.assertEqual(self.site._registry[Person].search_fields, ["name"])
-        self.assertEqual(self.site._registry[Person].list_display, ["__str__"])
-        self.assertTrue(self.site._registry[Person].save_on_top)
+        person_admin = self.site.get_model_admin(Person)
+        self.assertEqual(person_admin.search_fields, ["name"])
+        self.assertEqual(person_admin.list_display, ["__str__"])
+        self.assertIs(person_admin.save_on_top, True)
 
     def test_iterable_registration(self):
         self.site.register([Person, Place], search_fields=["name"])
-        self.assertIsInstance(self.site._registry[Person], admin.ModelAdmin)
-        self.assertEqual(self.site._registry[Person].search_fields, ["name"])
-        self.assertIsInstance(self.site._registry[Place], admin.ModelAdmin)
-        self.assertEqual(self.site._registry[Place].search_fields, ["name"])
+        self.assertIsInstance(self.site.get_model_admin(Person), admin.ModelAdmin)
+        self.assertEqual(self.site.get_model_admin(Person).search_fields, ["name"])
+        self.assertIsInstance(self.site.get_model_admin(Place), admin.ModelAdmin)
+        self.assertEqual(self.site.get_model_admin(Place).search_fields, ["name"])
         self.site.unregister([Person, Place])
         self.assertEqual(self.site._registry, {})
 
@@ -116,18 +122,26 @@ class TestRegistrationDecorator(SimpleTestCase):
 
     def test_basic_registration(self):
         register(Person)(NameAdmin)
-        self.assertIsInstance(self.default_site._registry[Person], admin.ModelAdmin)
+        self.assertIsInstance(
+            self.default_site.get_model_admin(Person), admin.ModelAdmin
+        )
         self.default_site.unregister(Person)
 
     def test_custom_site_registration(self):
         register(Person, site=self.custom_site)(NameAdmin)
-        self.assertIsInstance(self.custom_site._registry[Person], admin.ModelAdmin)
+        self.assertIsInstance(
+            self.custom_site.get_model_admin(Person), admin.ModelAdmin
+        )
 
     def test_multiple_registration(self):
         register(Traveler, Place)(NameAdmin)
-        self.assertIsInstance(self.default_site._registry[Traveler], admin.ModelAdmin)
+        self.assertIsInstance(
+            self.default_site.get_model_admin(Traveler), admin.ModelAdmin
+        )
         self.default_site.unregister(Traveler)
-        self.assertIsInstance(self.default_site._registry[Place], admin.ModelAdmin)
+        self.assertIsInstance(
+            self.default_site.get_model_admin(Place), admin.ModelAdmin
+        )
         self.default_site.unregister(Place)
 
     def test_wrapped_class_not_a_model_admin(self):
diff --git a/tests/admin_views/test_autocomplete_view.py b/tests/admin_views/test_autocomplete_view.py
index 90533ea5b0..f8ab32717a 100644
--- a/tests/admin_views/test_autocomplete_view.py
+++ b/tests/admin_views/test_autocomplete_view.py
@@ -3,6 +3,7 @@ import json
 from contextlib import contextmanager
 
 from django.contrib import admin
+from django.contrib.admin.sites import NotRegistered
 from django.contrib.admin.tests import AdminSeleniumTestCase
 from django.contrib.admin.views.autocomplete import AutocompleteJsonView
 from django.contrib.auth.models import Permission, User
@@ -61,8 +62,11 @@ site.register(Toy, autocomplete_fields=["child"])
 
 @contextmanager
 def model_admin(model, model_admin, admin_site=site):
-    org_admin = admin_site._registry.get(model)
-    if org_admin:
+    try:
+        org_admin = admin_site.get_model_admin(model)
+    except NotRegistered:
+        org_admin = None
+    else:
         admin_site.unregister(model)
     admin_site.register(model, model_admin)
     try:
diff --git a/tests/gis_tests/geoadmin/tests.py b/tests/gis_tests/geoadmin/tests.py
index a7e5700b49..869307328e 100644
--- a/tests/gis_tests/geoadmin/tests.py
+++ b/tests/gis_tests/geoadmin/tests.py
@@ -9,7 +9,7 @@ class GeoAdminTest(SimpleTestCase):
     admin_site = site  # ModelAdmin
 
     def test_widget_empty_string(self):
-        geoadmin = self.admin_site._registry[City]
+        geoadmin = self.admin_site.get_model_admin(City)
         form = geoadmin.get_changelist_form(None)({"point": ""})
         with self.assertRaisesMessage(AssertionError, "no logs"):
             with self.assertLogs("django.contrib.gis", "ERROR"):
@@ -21,7 +21,7 @@ class GeoAdminTest(SimpleTestCase):
         )
 
     def test_widget_invalid_string(self):
-        geoadmin = self.admin_site._registry[City]
+        geoadmin = self.admin_site.get_model_admin(City)
         form = geoadmin.get_changelist_form(None)({"point": "INVALID()"})
         with self.assertLogs("django.contrib.gis", "ERROR") as cm:
             output = str(form["point"])
@@ -38,7 +38,7 @@ class GeoAdminTest(SimpleTestCase):
         )
 
     def test_widget_has_changed(self):
-        geoadmin = self.admin_site._registry[City]
+        geoadmin = self.admin_site.get_model_admin(City)
         form = geoadmin.get_changelist_form(None)()
         has_changed = form.fields["point"].has_changed
 
@@ -59,7 +59,7 @@ class GISAdminTests(GeoAdminTest):
     admin_site = site_gis  # GISModelAdmin
 
     def test_default_gis_widget_kwargs(self):
-        geoadmin = self.admin_site._registry[City]
+        geoadmin = self.admin_site.get_model_admin(City)
         form = geoadmin.get_changelist_form(None)()
         widget = form["point"].field.widget
         self.assertEqual(widget.attrs["default_lat"], 47)
@@ -67,7 +67,7 @@ class GISAdminTests(GeoAdminTest):
         self.assertEqual(widget.attrs["default_zoom"], 12)
 
     def test_custom_gis_widget_kwargs(self):
-        geoadmin = site_gis_custom._registry[City]
+        geoadmin = site_gis_custom.get_model_admin(City)
         form = geoadmin.get_changelist_form(None)()
         widget = form["point"].field.widget
         self.assertEqual(widget.attrs["default_lat"], 55)
diff --git a/tests/modeladmin/tests.py b/tests/modeladmin/tests.py
index 627029c9cf..f2763ecc0f 100644
--- a/tests/modeladmin/tests.py
+++ b/tests/modeladmin/tests.py
@@ -871,7 +871,7 @@ class ModelAdminTests(TestCase):
             username="bob", email="bob@test.com", password="test"
         )
         self.site.register(Band, ModelAdmin)
-        ma = self.site._registry[Band]
+        ma = self.site.get_model_admin(Band)
         (
             deletable_objects,
             model_count,
@@ -898,7 +898,7 @@ class ModelAdminTests(TestCase):
                 return False
 
         self.site.register(Band, TestModelAdmin)
-        ma = self.site._registry[Band]
+        ma = self.site.get_model_admin(Band)
         (
             deletable_objects,
             model_count,