add warning for run pytest xdist with capture queries

Author: Friskes

README.md

@@ -38,6 +38,10 @@
     - `explain_opts`: Parameters for explain. *(for more information about the parameters for explain, see the documentation for your DBMS).*
     - `connection`: Connecting to your database, by default: django.db.connection
 
+
+### > WARNING: If you use `pytest-xdist` and run the test with the `-n <workers>` flag, the results will not be reflected in the terminal. Remove the `-n <workers>` flag to display them.
+
+
 ## Usage examples
 
 ```python
@@ -124,5 +128,5 @@ settings.PRINTER_HANDLERS.append("path.to.your.handler.SomeHandler")
 ```
 
 ## TODO:
-1. Add support for async loop and async func decorator, __acall__, __aiter__, __anext__
+1. Add support for async loop and async func decorator, __call__, __aiter__, __anext__
 2. Add support for other ORM's, SQLAlchemy, etc.

src/capture_db_queries/decorators.py

@@ -2,6 +2,7 @@
 
 import functools
 import statistics
+import sys
 import time
 import warnings
 from functools import wraps
@@ -34,6 +35,24 @@
 __all__ = ('CaptureQueries', 'capture_queries', 'ExtCaptureQueriesContext')
 
 
+def _detect_pytest_xdist():
+    try:
+        is_pytest = sys.argv[0].endswith('pytest')
+    except IndexError:
+        pass
+    else:
+        is_xdist = '-n' in sys.argv
+        is_spot_test_launch = any('.py::' in arg for arg in sys.argv)
+
+        if is_pytest and is_xdist and is_spot_test_launch:
+            warnings.warn(
+                'If you want to see the result of CaptureQueries, then remove the '
+                '-n <workers> parameter when starting pytest or use --capture=tee-sys -rP parameters.',
+                category=UserWarning,
+                stacklevel=2,
+            )
+
+
 class CaptureQueries:
     """
     #### Class to simplify the search for slow and suboptimal sql queries\
@@ -70,6 +89,10 @@ class CaptureQueries:
 
     ---
 
+    #### WARNING: If you use `pytest-xdist` and run the test with the `-n <workers>` flag, the results will not be reflected in the terminal. Remove the `-n <workers>` flag to display them.
+
+    ---
+
     #### Usage examples::
 
         for ctx in CaptureQueries(number_runs=2, advanced_verb=True):
@@ -92,6 +115,7 @@ def test_request():
         # OR
 
         # NOTE: The with context manager does not support multi-launch number_runs > 1
+        # NOTE: Also you can use `async with` if you capture queries in async context.
         with CaptureQueries(number_runs=1, advanced_verb=True) as ctx:
             response = self.client.get(url)
 
@@ -140,6 +164,7 @@ def __init__(
         explain_opts: dict[str, Any] | None = None,
         connection: BaseDatabaseWrapper | None = None,
     ) -> None:
+        _detect_pytest_xdist()
         log.debug('')
 
         self.assert_q_count = assert_q_count