feat: ensure we can evaluate same queryset twice without false positives

hooks/pre-commit

@@ -1,5 +1,5 @@
 #!/bin/sh
 
-make format-check
-make typecheck
+make format-check || exit 1
+make typecheck || exit 1
 

hooks/pre-push

@@ -1,3 +1,3 @@
 #!/bin/sh
 
-make test
+make test || exit 1

src/queryspy/__init__.py

@@ -1,10 +1,11 @@
 from .errors import NPlusOneError, QuerySpyError
-from .listeners import queryspy_context, setup, teardown
+from .listeners import queryspy_context, queryspy_ignore, setup, teardown
 
 __all__ = [
     "QuerySpyError",
     "NPlusOneError",
     "setup",
     "teardown",
     "queryspy_context",
+    "queryspy_ignore",
 ]

src/queryspy/listeners.py

@@ -69,3 +69,12 @@ def queryspy_context():
     finally:
         n_plus_one_listener.reset()
         _is_in_context.reset(token)
+
+
+@contextmanager
+def queryspy_ignore():
+    token = _is_in_context.set(False)
+    try:
+        yield
+    finally:
+        _is_in_context.reset(token)

tests/test_nplusones.py

@@ -1,6 +1,8 @@
 import re
 
 import pytest
+from django.db import connection
+from django.test.utils import CaptureQueriesContext
 from djangoproject.social.models import Post, Profile, User
 from queryspy import NPlusOneError, queryspy_context
 
@@ -39,6 +41,17 @@ def test_detects_nplusone_in_reverse_many_to_one():
         _ = list(user.posts.all())
 
 
+def test_no_false_positive_when_calling_reverse_many_to_one_twice():
+    user = UserFactory.create()
+    PostFactory.create(author=user)
+
+    with queryspy_context(), CaptureQueriesContext(connection) as ctx:
+        queryset = user.posts.all()
+        list(queryset)  # evaluate queryset once
+        list(queryset)  # evalute again (cached)
+        assert len(ctx.captured_queries) == 1
+
+
 @queryspy_context()
 def test_detects_nplusone_in_forward_one_to_one():
     [user_1, user_2] = UserFactory.create_batch(2)