DjangoTestSuiteRunner cannot run with dummy database backend

[Claude Paroz]

(from https://code.djangoproject.com/ticket/18575#comment:9)

To support Django app testing without requiring a database, one can omit the DATABASES setting so as the default dummy backend is configured. Unfortunately, DjangoTestSuiteRunner does not support this configuration, as it raises ImproperlyConfigured at the time the connection.creation.create_test_db is called.

[Jan Bednařík]

Here is patch: ​https://github.com/django/django/pull/475

Patch skips calling create_test_db and destory_test_db for dummy database backend.

Testing without database (with dummy database backend) works only for SimpleTestCase.

(I added myself into authors because It's my 4th small patch and I did also triaging of few tickets.)

[Jan Bednařík]

I made a mistake in patch...

[Jan Bednařík]

Patch and pull request has been updated, ready for review.

[Simon Charette]

What about providing a dummy database creation class that ignores create_test_db and destroy_test_db instead?

django/db/backends/dummy/base.py

@@ -31 +31 @@
 class DatabaseClient(BaseDatabaseClient):
     runshell = complain
 
+class DatabaseCreation(BaseDatabaseCreation):
+    create_test_db = ignore
+    destroy_test_db = ignore
+
 class DatabaseIntrospection(BaseDatabaseIntrospection):
     get_table_list = complain
     get_table_description = complain
@@ -64 +68 @@
         self.features = BaseDatabaseFeatures(self)
         self.ops = DatabaseOperations(self)
         self.client = DatabaseClient(self)
-        self.creation = BaseDatabaseCreation(self)
+        self.creation = DatabaseCreation(self)
         self.introspection = DatabaseIntrospection(self)
         self.validation = BaseDatabaseValidation(self)

This also allows SimpleTestCase to work just fine.

[Claude Paroz]

Yes, Simon's solution is a lot more elegant/pythonic. I will add a test and commit.

[Claude Paroz <claude@…>]

In b740da3504ea3b9c841f5a9eb14191a0b5410565:

Fixed #19192 -- Allowed running tests with dummy db backend

Thanks Simon Charette for the initial patch, and Jan Bednařík for
his work on the ticket.

[Claude Paroz <claude@…>]

In 96301d21bb2ec7c5e06e3cea54fa2cdcd25a464d:

[1.5.x] Fixed #19192 -- Allowed running tests with dummy db backend

Thanks Simon Charette for the initial patch, and Jan Bednařík for
his work on the ticket.
Backport of b740da3504 from master.