Reorganized backends tests.

tests/backends/mysql/tests.py

@@ -0,0 +1,91 @@
+import unittest
+from contextlib import contextmanager
+
+from django.core.exceptions import ImproperlyConfigured
+from django.db import connection
+from django.test import TestCase, override_settings
+
+
+@contextmanager
+def get_connection():
+    new_connection = connection.copy()
+    yield new_connection
+    new_connection.close()
+
+
+@override_settings(DEBUG=True)
+@unittest.skipUnless(connection.vendor == 'mysql', 'MySQL tests')
+class IsolationLevelTests(TestCase):
+
+    read_committed = 'read committed'
+    repeatable_read = 'repeatable read'
+    isolation_values = {
+        level: level.replace(' ', '-').upper()
+        for level in (read_committed, repeatable_read)
+    }
+
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+        configured_isolation_level = connection.isolation_level or cls.isolation_values[cls.repeatable_read]
+        cls.configured_isolation_level = configured_isolation_level.upper()
+        cls.other_isolation_level = (
+            cls.read_committed
+            if configured_isolation_level != cls.isolation_values[cls.read_committed]
+            else cls.repeatable_read
+        )
+
+    @staticmethod
+    def get_isolation_level(connection):
+        with connection.cursor() as cursor:
+            cursor.execute("SELECT @@session.tx_isolation")
+            return cursor.fetchone()[0]
+
+    def test_auto_is_null_auto_config(self):
+        query = 'set sql_auto_is_null = 0'
+        connection.init_connection_state()
+        last_query = connection.queries[-1]['sql'].lower()
+        if connection.features.is_sql_auto_is_null_enabled:
+            self.assertIn(query, last_query)
+        else:
+            self.assertNotIn(query, last_query)
+
+    def test_connect_isolation_level(self):
+        self.assertEqual(self.get_isolation_level(connection), self.configured_isolation_level)
+
+    def test_setting_isolation_level(self):
+        with get_connection() as new_connection:
+            new_connection.settings_dict['OPTIONS']['isolation_level'] = self.other_isolation_level
+            self.assertEqual(
+                self.get_isolation_level(new_connection),
+                self.isolation_values[self.other_isolation_level]
+            )
+
+    def test_uppercase_isolation_level(self):
+        # Upper case values are also accepted in 'isolation_level'.
+        with get_connection() as new_connection:
+            new_connection.settings_dict['OPTIONS']['isolation_level'] = self.other_isolation_level.upper()
+            self.assertEqual(
+                self.get_isolation_level(new_connection),
+                self.isolation_values[self.other_isolation_level]
+            )
+
+    def test_default_isolation_level(self):
+        # If not specified in settings, the default is read committed.
+        with get_connection() as new_connection:
+            new_connection.settings_dict['OPTIONS'].pop('isolation_level', None)
+            self.assertEqual(
+                self.get_isolation_level(new_connection),
+                self.isolation_values[self.read_committed]
+            )
+
+    def test_isolation_level_validation(self):
+        new_connection = connection.copy()
+        new_connection.settings_dict['OPTIONS']['isolation_level'] = 'xxx'
+        msg = (
+            "Invalid transaction isolation level 'xxx' specified.\n"
+            "Use one of 'read committed', 'read uncommitted', "
+            "'repeatable read', 'serializable', or None."
+        )
+        with self.assertRaisesMessage(ImproperlyConfigured, msg):
+            new_connection.cursor()