How to extend Django's test database with custom SQL view? - django

Question

I'm using Django 2.1 with MySQL.
I have one custom SQL view, which is bound with a model with Meta managed = False. Django's TestCase has no idea how the view is created, so I'd like to provide SQL command to create this view. The best option would be to do this on database create, but I have no idea how to do that.
What I've done so far was to override TestCase's setUp method. It looks like that:
class TaskDoneViewTest(TestCase):
def setUp(self):
"""
Create custom SQL view
"""
cursor = connection.cursor()
file_handle = open('app/tests/create_sql_view.sql', 'r+')
sql_file = File(file_handle)
sql = sql_file.read()
cursor.execute(sql)
cursor.close()
def test_repeatable_task_done(self):
# ...
def test_one_time_task_done(self):
# ...
I've got this solution from similar SO post: How to use database view in test cases. It would be a nice temporary solution, but the problem is with all those 2 test cases active I'm getting following error:
$ python manage.py test app.tests
Creating test database for alias 'default'...
System check identified no issues (0 silenced).
...E..
======================================================================
ERROR: test_repeatable_task_done (app.tests.test_views.TaskDoneViewTest)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/home/asmox/AppDev/Python/bubblechecklist/project_root/app/tests/test_views.py", line 80, in setUp
cursor.execute(sql)
File "/home/asmox/AppDev/Python/bubblechecklist/env/lib/python3.6/site-packages/django/db/backends/utils.py", line 68, in execute
return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
File "/home/asmox/AppDev/Python/bubblechecklist/env/lib/python3.6/site-packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers
return executor(sql, params, many, context)
File "/home/asmox/AppDev/Python/bubblechecklist/env/lib/python3.6/site-packages/django/db/backends/utils.py", line 80, in _execute
self.db.validate_no_broken_transaction()
File "/home/asmox/AppDev/Python/bubblechecklist/env/lib/python3.6/site-packages/django/db/backends/base/base.py", line 437, in validate_no_broken_transaction
"An error occurred in the current transaction. You can't "
django.db.transaction.TransactionManagementError: An error occurred in the current transaction. You can't execute queries until the end of the 'atomic' block.
For some reason this error doesn't happen when I have only one test case active (why?).This error remains until I change my test's base class from TestCase to TransactionTestCase.
Well, I would ask why this happen and if there is any solution to get it okay with simple TestCase class, because my test for now has nothing to do with transactions and I find this working solutions a bit too dirty, but...
I would more likely stick to the main issue, that is, to globally (for all my test cases) do the following thing:
When testing database is created, do one more custom SQL from provided file. It is going to create required view
Can you please help me how to do that?

Answer 1

If you read the documentation for TestCase, you'll see that it wraps each test in a double transaction, one at the class level and one at the test level. The setUp() method runs for each test and is thus inside this double wrapping.
As shown in the above mentioned docs, it is suggested you use setUpTestData() to set up your db at the class level. This is also where you'd add initial data to your db for all your tests to use.