Fixed #14415 -- Used the test database name in BaseDatabaseCreation.test_db_signature().

django/db/backends/base/creation.py

@@ -299,5 +299,5 @@ class BaseDatabaseCreation(object):
             settings_dict['HOST'],
             settings_dict['PORT'],
             settings_dict['ENGINE'],
-            settings_dict['NAME']
+            self._get_test_db_name(),
         )

tests/backends/test_creation.py

@@ -0,0 +1,42 @@
+import copy
+
+from django.db import DEFAULT_DB_ALIAS, connections
+from django.db.backends.base.creation import (
+    TEST_DATABASE_PREFIX, BaseDatabaseCreation,
+)
+from django.test import SimpleTestCase
+
+
+class TestDbSignatureTests(SimpleTestCase):
+
+    def get_connection_copy(self):
+        # Get a copy of the default connection. (Can't use django.db.connection
+        # because it'll modify the default connection itself.)
+        test_connection = copy.copy(connections[DEFAULT_DB_ALIAS])
+        test_connection.settings_dict = copy.copy(connections[DEFAULT_DB_ALIAS].settings_dict)
+        return test_connection
+
+    def test_default_name(self):
+        # A test db name isn't set.
+        prod_name = 'hodor'
+        test_connection = self.get_connection_copy()
+        test_connection.settings_dict['NAME'] = prod_name
+        test_connection.settings_dict['TEST'] = {'NAME': None}
+        signature = BaseDatabaseCreation(test_connection).test_db_signature()
+        self.assertEqual(signature[3], TEST_DATABASE_PREFIX + prod_name)
+
+    def test_custom_test_name(self):
+        # A regular test db name is set.
+        test_name = 'hodor'
+        test_connection = self.get_connection_copy()
+        test_connection.settings_dict['TEST'] = {'NAME': test_name}
+        signature = BaseDatabaseCreation(test_connection).test_db_signature()
+        self.assertEqual(signature[3], test_name)
+
+    def test_custom_test_name_with_test_prefix(self):
+        # A test db name prefixed with TEST_DATABASE_PREFIX is set.
+        test_name = TEST_DATABASE_PREFIX + 'hodor'
+        test_connection = self.get_connection_copy()
+        test_connection.settings_dict['TEST'] = {'NAME': test_name}
+        signature = BaseDatabaseCreation(test_connection).test_db_signature()
+        self.assertEqual(signature[3], test_name)