Issue #26325: Added test.support.check_no_resource_warning() to check that

no ResourceWarning is emitted.

1 files changed, 23 insertions, 1 deletions

diff --git a/Lib/test/support/__init__.py b/Lib/test/support/__init__.py
index 58dcc8a..a2ef93d 100644
--- a/Lib/test/support/__init__.py
+++ b/Lib/test/support/__init__.py
@@ -102,7 +102,8 @@ __all__ = [
     # threads
     "threading_setup", "threading_cleanup", "reap_threads", "start_threads",
     # miscellaneous
-    "check_warnings", "EnvironmentVarGuard", "run_with_locale", "swap_item",
+    "check_warnings", "check_no_resource_warning", "EnvironmentVarGuard",
+    "run_with_locale", "swap_item",
     "swap_attr", "Matcher", "set_memlimit", "SuppressCrashReport", "sortdict",
     "run_with_tz",
     ]
@@ -1149,6 +1150,27 @@ def check_warnings(*filters, **kwargs):
     return _filterwarnings(filters, quiet)
 
 
+@contextlib.contextmanager
+def check_no_resource_warning(testcase):
+    """Context manager to check that no ResourceWarning is emitted.
+
+    Usage:
+
+        with check_no_resource_warning(self):
+            f = open(...)
+            ...
+            del f
+
+    You must remove the object which may emit ResourceWarning before
+    the end of the context manager.
+    """
+    with warnings.catch_warnings(record=True) as warns:
+        warnings.filterwarnings('always', category=ResourceWarning)
+        yield
+        gc_collect()
+    testcase.assertEqual(warns, [])
+
+
 class CleanImport(object):
     """Context manager to force import to return a new module reference.