Fixed #31277 -- Relaxed system check of m2m intermediary tables for db_table collision when database routers are installed.

Turned the error into a warning when database routers are installed.

1 files changed, 83 insertions, 0 deletions

diff --git a/tests/invalid_models_tests/test_models.py b/tests/invalid_models_tests/test_models.py
index 0df41c2952..438c327003 100644
--- a/tests/invalid_models_tests/test_models.py
+++ b/tests/invalid_models_tests/test_models.py
@@ -10,6 +10,10 @@ from django.test import SimpleTestCase, TestCase
 from django.test.utils import isolate_apps, override_settings, register_lookup
 
 
+class EmptyRouter:
+    pass
+
+
 def get_max_column_name_length():
     allowed_len = None
     db_alias = None
@@ -1044,6 +1048,32 @@ class OtherModelTests(SimpleTestCase):
             )
         ])
 
+    @override_settings(DATABASE_ROUTERS=['invalid_models_tests.test_models.EmptyRouter'])
+    def test_m2m_table_name_clash_database_routers_installed(self):
+        class Foo(models.Model):
+            bar = models.ManyToManyField('Bar', db_table='myapp_bar')
+
+            class Meta:
+                db_table = 'myapp_foo'
+
+        class Bar(models.Model):
+            class Meta:
+                db_table = 'myapp_bar'
+
+        self.assertEqual(Foo.check(), [
+            Warning(
+                "The field's intermediary table 'myapp_bar' clashes with the "
+                "table name of 'invalid_models_tests.Bar'.",
+                obj=Foo._meta.get_field('bar'),
+                hint=(
+                    "You have configured settings.DATABASE_ROUTERS. Verify "
+                    "that the table of 'invalid_models_tests.Bar' is "
+                    "correctly routed to a separate database."
+                ),
+                id='fields.W344',
+            ),
+        ])
+
     def test_m2m_field_table_name_clash(self):
         class Foo(models.Model):
             pass
@@ -1069,6 +1099,32 @@ class OtherModelTests(SimpleTestCase):
             )
         ])
 
+    @override_settings(DATABASE_ROUTERS=['invalid_models_tests.test_models.EmptyRouter'])
+    def test_m2m_field_table_name_clash_database_routers_installed(self):
+        class Foo(models.Model):
+            pass
+
+        class Bar(models.Model):
+            foos = models.ManyToManyField(Foo, db_table='clash')
+
+        class Baz(models.Model):
+            foos = models.ManyToManyField(Foo, db_table='clash')
+
+        self.assertEqual(Bar.check() + Baz.check(), [
+            Warning(
+                "The field's intermediary table 'clash' clashes with the "
+                "table name of 'invalid_models_tests.%s.foos'."
+                % clashing_model,
+                obj=model_cls._meta.get_field('foos'),
+                hint=(
+                    "You have configured settings.DATABASE_ROUTERS. Verify "
+                    "that the table of 'invalid_models_tests.%s.foos' is "
+                    "correctly routed to a separate database." % clashing_model
+                ),
+                id='fields.W344',
+            ) for model_cls, clashing_model in [(Bar, 'Baz'), (Baz, 'Bar')]
+        ])
+
     def test_m2m_autogenerated_table_name_clash(self):
         class Foo(models.Model):
             class Meta:
@@ -1090,6 +1146,33 @@ class OtherModelTests(SimpleTestCase):
             )
         ])
 
+    @override_settings(DATABASE_ROUTERS=['invalid_models_tests.test_models.EmptyRouter'])
+    def test_m2m_autogenerated_table_name_clash_database_routers_installed(self):
+        class Foo(models.Model):
+            class Meta:
+                db_table = 'bar_foos'
+
+        class Bar(models.Model):
+            # The autogenerated db_table is bar_foos.
+            foos = models.ManyToManyField(Foo)
+
+            class Meta:
+                db_table = 'bar'
+
+        self.assertEqual(Bar.check(), [
+            Warning(
+                "The field's intermediary table 'bar_foos' clashes with the "
+                "table name of 'invalid_models_tests.Foo'.",
+                obj=Bar._meta.get_field('foos'),
+                hint=(
+                    "You have configured settings.DATABASE_ROUTERS. Verify "
+                    "that the table of 'invalid_models_tests.Foo' is "
+                    "correctly routed to a separate database."
+                ),
+                id='fields.W344',
+            ),
+        ])
+
     def test_m2m_unmanaged_shadow_models_not_checked(self):
         class A1(models.Model):
             pass