Refs #28478 -- Prevented database feature based skipping on tests disallowing queries.

Database features may require a connection to be established to determine
whether or not they are enabled.

1 files changed, 29 insertions, 4 deletions

diff --git a/django/test/testcases.py b/django/test/testcases.py
index 0e1da33064..3dd14a08c0 100644
--- a/django/test/testcases.py
+++ b/django/test/testcases.py
@@ -1205,12 +1205,24 @@ class CheckCondition:
         return False
 
 
-def _deferredSkip(condition, reason):
+def _deferredSkip(condition, reason, name):
     def decorator(test_func):
+        nonlocal condition
         if not (isinstance(test_func, type) and
                 issubclass(test_func, unittest.TestCase)):
             @wraps(test_func)
             def skip_wrapper(*args, **kwargs):
+                if (args and isinstance(args[0], unittest.TestCase) and
+                        connection.alias not in getattr(args[0], 'databases', {})):
+                    raise ValueError(
+                        "%s cannot be used on %s as %s doesn't allow queries "
+                        "against the %r database." % (
+                            name,
+                            args[0],
+                            args[0].__class__.__qualname__,
+                            connection.alias,
+                        )
+                    )
                 if condition():
                     raise unittest.SkipTest(reason)
                 return test_func(*args, **kwargs)
@@ -1218,6 +1230,16 @@ def _deferredSkip(condition, reason):
         else:
             # Assume a class is decorated
             test_item = test_func
+            databases = getattr(test_item, 'databases', None)
+            if not databases or connection.alias not in databases:
+                # Defer raising to allow importing test class's module.
+                def condition():
+                    raise ValueError(
+                        "%s cannot be used on %s as it doesn't allow queries "
+                        "against the '%s' database." % (
+                            name, test_item, connection.alias,
+                        )
+                    )
             # Retrieve the possibly existing value from the class's dict to
             # avoid triggering the descriptor.
             skip = test_func.__dict__.get('__unittest_skip__')
@@ -1233,7 +1255,8 @@ def skipIfDBFeature(*features):
     """Skip a test if a database has at least one of the named features."""
     return _deferredSkip(
         lambda: any(getattr(connection.features, feature, False) for feature in features),
-        "Database has feature(s) %s" % ", ".join(features)
+        "Database has feature(s) %s" % ", ".join(features),
+        'skipIfDBFeature',
     )
 
 
@@ -1241,7 +1264,8 @@ def skipUnlessDBFeature(*features):
     """Skip a test unless a database has all the named features."""
     return _deferredSkip(
         lambda: not all(getattr(connection.features, feature, False) for feature in features),
-        "Database doesn't support feature(s): %s" % ", ".join(features)
+        "Database doesn't support feature(s): %s" % ", ".join(features),
+        'skipUnlessDBFeature',
     )
 
 
@@ -1249,7 +1273,8 @@ def skipUnlessAnyDBFeature(*features):
     """Skip a test unless a database has any of the named features."""
     return _deferredSkip(
         lambda: not any(getattr(connection.features, feature, False) for feature in features),
-        "Database doesn't support any of the feature(s): %s" % ", ".join(features)
+        "Database doesn't support any of the feature(s): %s" % ", ".join(features),
+        'skipUnlessAnyDBFeature',
     )