diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index 60a189b..cec47ce 100644
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -622,10 +622,9 @@
         """Returns True if the event loop was closed."""
         return self._closed
 
-    def __del__(self):
+    def __del__(self, _warn=warnings.warn):
         if not self.is_closed():
-            warnings.warn(f"unclosed event loop {self!r}", ResourceWarning,
-                          source=self)
+            _warn(f"unclosed event loop {self!r}", ResourceWarning, source=self)
             if not self.is_running():
                 self.close()
 
diff --git a/Lib/asyncio/base_subprocess.py b/Lib/asyncio/base_subprocess.py
index b547c44..f503f78 100644
--- a/Lib/asyncio/base_subprocess.py
+++ b/Lib/asyncio/base_subprocess.py
@@ -120,10 +120,9 @@
 
             # Don't clear the _proc reference yet: _post_init() may still run
 
-    def __del__(self):
+    def __del__(self, _warn=warnings.warn):
         if not self._closed:
-            warnings.warn(f"unclosed transport {self!r}", ResourceWarning,
-                          source=self)
+            _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
             self.close()
 
     def get_pid(self):
diff --git a/Lib/asyncio/proactor_events.py b/Lib/asyncio/proactor_events.py
index da204c6..3a1826e 100644
--- a/Lib/asyncio/proactor_events.py
+++ b/Lib/asyncio/proactor_events.py
@@ -89,10 +89,9 @@
             self._read_fut.cancel()
             self._read_fut = None
 
-    def __del__(self):
+    def __del__(self, _warn=warnings.warn):
         if self._sock is not None:
-            warnings.warn(f"unclosed transport {self!r}", ResourceWarning,
-                          source=self)
+            _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
             self.close()
 
     def _fatal_error(self, exc, message='Fatal error on pipe transport'):
diff --git a/Lib/asyncio/selector_events.py b/Lib/asyncio/selector_events.py
index 112c4b1..93b6889 100644
--- a/Lib/asyncio/selector_events.py
+++ b/Lib/asyncio/selector_events.py
@@ -658,10 +658,9 @@
             self._loop._remove_writer(self._sock_fd)
             self._loop.call_soon(self._call_connection_lost, None)
 
-    def __del__(self):
+    def __del__(self, _warn=warnings.warn):
         if self._sock is not None:
-            warnings.warn(f"unclosed transport {self!r}", ResourceWarning,
-                          source=self)
+            _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
             self._sock.close()
 
     def _fatal_error(self, exc, message='Fatal error on transport'):
diff --git a/Lib/asyncio/sslproto.py b/Lib/asyncio/sslproto.py
index 12fdb0d..4278560 100644
--- a/Lib/asyncio/sslproto.py
+++ b/Lib/asyncio/sslproto.py
@@ -316,10 +316,9 @@
         self._closed = True
         self._ssl_protocol._start_shutdown()
 
-    def __del__(self):
+    def __del__(self, _warn=warnings.warn):
         if not self._closed:
-            warnings.warn(f"unclosed transport {self!r}", ResourceWarning,
-                          source=self)
+            _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
             self.close()
 
     def is_reading(self):
diff --git a/Lib/asyncio/unix_events.py b/Lib/asyncio/unix_events.py
index 1a62db4..73d4bda 100644
--- a/Lib/asyncio/unix_events.py
+++ b/Lib/asyncio/unix_events.py
@@ -511,10 +511,9 @@
         if not self._closing:
             self._close(None)
 
-    def __del__(self):
+    def __del__(self, _warn=warnings.warn):
         if self._pipe is not None:
-            warnings.warn(f"unclosed transport {self!r}", ResourceWarning,
-                          source=self)
+            _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
             self._pipe.close()
 
     def _fatal_error(self, exc, message='Fatal error on pipe transport'):
@@ -707,10 +706,9 @@
             # write_eof is all what we needed to close the write pipe
             self.write_eof()
 
-    def __del__(self):
+    def __del__(self, _warn=warnings.warn):
         if self._pipe is not None:
-            warnings.warn(f"unclosed transport {self!r}", ResourceWarning,
-                          source=self)
+            _warn(f"unclosed transport {self!r}", ResourceWarning, source=self)
             self._pipe.close()
 
     def abort(self):
diff --git a/Lib/asyncio/windows_utils.py b/Lib/asyncio/windows_utils.py
index 9e22f6e..ef277fa 100644
--- a/Lib/asyncio/windows_utils.py
+++ b/Lib/asyncio/windows_utils.py
@@ -107,10 +107,9 @@
             CloseHandle(self._handle)
             self._handle = None
 
-    def __del__(self):
+    def __del__(self, _warn=warnings.warn):
         if self._handle is not None:
-            warnings.warn(f"unclosed {self!r}", ResourceWarning,
-                          source=self)
+            _warn(f"unclosed {self!r}", ResourceWarning, source=self)
             self.close()
 
     def __enter__(self):