id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
35402	DatabaseFeatures.django_test_skips crashes when it references a class in another test module	Tim Graham	Jacob Walls	"Since the introduction of `DatabaseFeatures.django_test_skips` (#32178), I've used it to skip test classes, however, this can crash if there are multiple test modules in a package.

To reproduce, first make this modification to skip a class
{{{#!diff
diff --git a/django/db/backends/sqlite3/features.py b/django/db/backends/sqlite3/features.py
index d95c6fb2d1..51229fe970 100644
--- a/django/db/backends/sqlite3/features.py
+++ b/django/db/backends/sqlite3/features.py
@@ -68,8 +68,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     def django_test_skips(self):
         skips = {
             ""SQLite stores values rounded to 15 significant digits."": {
-                ""model_fields.test_decimalfield.DecimalFieldTests.""
-                ""test_fetch_from_db_without_float_rounding"",
+                ""model_fields.test_decimalfield.DecimalFieldTests"",
             },
             ""SQLite naively remakes the table on field alteration."": {
}}}

Then try to execute a test module in `model_fields` besides the one with the skip:
{{{#!shell
$ ./tests/runtests.py model_fields.test_autofield
Testing against Django installed in '/home/tim/code/django/django' with up to 3 processes
Found 62 test(s).
Creating test database for alias 'default'...
Traceback (most recent call last):
  File ""/home/tim/code/django/django/utils/module_loading.py"", line 30, in import_string
    return cached_import(module_path, class_name)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""/home/tim/code/django/django/utils/module_loading.py"", line 16, in cached_import
    return getattr(module, class_name)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: module 'model_fields' has no attribute 'test_decimalfield'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File ""/home/tim/code/django/./tests/runtests.py"", line 784, in <module>
    failures = django_tests(
               ^^^^^^^^^^^^^
  File ""/home/tim/code/django/./tests/runtests.py"", line 422, in django_tests
    failures = test_runner.run_tests(test_labels)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""/home/tim/code/django/django/test/runner.py"", line 1066, in run_tests
    old_config = self.setup_databases(
                 ^^^^^^^^^^^^^^^^^^^^^
  File ""/home/tim/code/django/django/test/runner.py"", line 964, in setup_databases
    return _setup_databases(
           ^^^^^^^^^^^^^^^^^
  File ""/home/tim/code/django/django/test/utils.py"", line 206, in setup_databases
    connection.creation.create_test_db(
  File ""/home/tim/code/django/django/db/backends/base/creation.py"", line 102, in create_test_db
    self.mark_expected_failures_and_skips()
  File ""/home/tim/code/django/django/db/backends/base/creation.py"", line 356, in mark_expected_failures_and_skips
    test_case = import_string(test_case_name)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""/home/tim/code/django/django/utils/module_loading.py"", line 32, in import_string
    raise ImportError(
ImportError: Module ""model_fields"" does not define a ""test_decimalfield"" attribute/class
}}}

A naive fix:
{{{#!diff
diff --git a/django/db/backends/base/creation.py b/django/db/backends/base/creation.py
index 6856fdb596..f6cc270b16 100644
--- a/django/db/backends/base/creation.py
+++ b/django/db/backends/base/creation.py
@@ -350,6 +350,9 @@ class BaseDatabaseCreation:
                 test_app = test_name.split(""."")[0]
                 # Importing a test app that isn't installed raises RuntimeError.
                 if test_app in settings.INSTALLED_APPS:
+                    # If this is a a test class, it may need to be imported.
+                    if test_name.count(""."") == 2:
+                        import_string(test_name)
                     test_case = import_string(test_case_name)
                     test_method = getattr(test_case, test_method_name)
                     setattr(test_case, test_method_name, skip(reason)(test_method))
}}}"	Bug	closed	Database layer (models, ORM)	dev	Normal	fixed			Ready for checkin	1	0	0	0	0	0