Backport test.support.check_no_warnings

Author: encukou

Lib/test/support/__init__.py

@@ -1244,6 +1244,30 @@ def check_warnings(*filters, **kwargs):
     return _filterwarnings(filters, quiet)
 
 
+@contextlib.contextmanager
+def check_no_warnings(testcase, message='', category=Warning, force_gc=False):
+    """Context manager to check that no warnings are emitted.
+
+    This context manager enables a given warning within its scope
+    and checks that no warnings are emitted even with that warning
+    enabled.
+
+    If force_gc is True, a garbage collection is attempted before checking
+    for warnings. This may help to catch warnings emitted when objects
+    are deleted, such as ResourceWarning.
+
+    Other keyword arguments are passed to warnings.filterwarnings().
+    """
+    with warnings.catch_warnings(record=True) as warns:
+        warnings.filterwarnings('always',
+                                message=message,
+                                category=category)
+        yield
+        if force_gc:
+            gc_collect()
+    testcase.assertEqual(warns, [])
+
+
 @contextlib.contextmanager
 def check_no_resource_warning(testcase):
     """Context manager to check that no ResourceWarning is emitted.