Django: is there a way to count SQL queries from an unit test?

Question

I am trying to find out the number of queries executed by a utility function. I have written a unit test for this function and the function is working well. What I would like to

Answer 1

Here is the working prototype of context manager withAssertNumQueriesLessThen

import json
from contextlib import contextmanager
from django.test.utils import CaptureQueriesContext
from django.db import connections

@contextmanager
def withAssertNumQueriesLessThen(self, value, using='default', verbose=False):
    with CaptureQueriesContext(connections[using]) as context:
        yield   # your test will be run here
    if verbose:
        msg = "\r\n%s" % json.dumps(context.captured_queries, indent=4)
    else:
        msg = None
    self.assertLess(len(context.captured_queries), value, msg=msg)

It can be simply used in your unit tests for example for checking the number of queries per Django REST API call

    with self.withAssertNumQueriesLessThen(10):
        response = self.client.get('contacts/')
        self.assertEqual(response.status_code, 200)

Also you can provide exact DB using and verbose if you want to pretty-print list of actual queries to stdout