Fixed #36327 -- Added multiple database support to assertNumQueries() #19380
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Please retitle your commit and PR: https://docs.djangoproject.com/en/dev/internals/contributing/committing-code/#committing-guidelines |
adamchainz
reviewed
Apr 14, 2025
| return results | ||
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| class LazyExitStack: |
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Why create this class? Afaict can make a plain ExitStack during _AssertNumQueriesContext.__enter__ instead.
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This will not work. ExitStack evaluates the __enter__ method right away. I added a test to demostrate what im trying to accomplish:
def test_deferred(self):
context = self.assertNumQueries(0)
Person.objects.count()
with context:
passusing ExitStack: (ps this was a quick and dirty example)
diff --git a/django/test/testcases.py b/django/test/testcases.py
index 8a3e47ed63..fa58471c88 100644
--- a/django/test/testcases.py
+++ b/django/test/testcases.py
@@ -102,14 +102,19 @@ class _AssertNumQueriesContext:
def __init__(self, test_case, num, connections_):
self.test_case = test_case
self.num = num
- self.cm = LazyExitStack()
+ # self.cm = LazyExitStack()
+ import contextlib
+ self.cm = contextlib.ExitStack()
+ self.cms = []
for conn in connections_:
- self.cm.enter_context(CaptureQueriesContext(conn))
+ context = CaptureQueriesContext(conn)
+ self.cms.append(context)
+ self.cm.enter_context(context)
@property
def captured_queries(self):
return [
- query for cm in self.cm.context_managers for query in cm.captured_queries
+ query for cm in self.cms for query in cm.captured_queries
]
def __len__(self):the tests fails:
======================================================================
FAIL: test_deferred (test_utils.tests.AssertNumQueriesContextManagerTests.test_deferred)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/django/source/tests/test_utils/tests.py", line 489, in test_deferred
with context:
^^^^^^^
AssertionError: 1 != 0 : 1 queries executed, 0 expected
Captured queries were:
1. SELECT COUNT(*) AS "__count" FROM "test_utils_person"
----------------------------------------------------------------------
Ran 1 test in 0.004s
kingbuzzman
commented
Apr 14, 2025
…/django into dev/test-multi-db-assert-num
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Closing per ticket. |
| """ | ||
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| def __init__(self): | ||
| self.context_managers = [] |
Comment on lines
+474
to
+475
| def enter_context(self, context_manager): | ||
| self.context_managers.append(context_manager) |
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enter_context is a bad method name. You are registering a context_manager, not entering it. Better: register_context.
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Trac ticket number
ticket-36327
Branch description
The goal is to enhance the behavior of
TestCase.assertNumQueries(). In large Django projects, the data structure is often split into multiple databases—for example, one for user data, another for business data, one for events, and even a dedicated one for certain monetary compliance logs. As a result, tests may need to validate query counts across several databases. For instance, you might have code that looks like this:The desired improvement is to simplify this syntax. Instead of writing a separate context manager for each database, you could pass multiple databases at once. For example:
Checklist
mainbranch.