Fix event loop leak when running tests (mitmproxy#7982)

* Fix event loop leak when running tests

Close event loop in `__exit__` method to avoid "OSError: [Errno 24] Too many open files"

* [autofix.ci] apply automated fixes

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

Author: DNEGEL3125

CHANGELOG.md

@@ -31,6 +31,8 @@
   ([#7971](https://github.com/mitmproxy/mitmproxy/pull/7971), @sleeyax, @mhils)
 - Fix URL of mitmweb when --web-host is an IPv6 address.
   ([#7963](https://github.com/mitmproxy/mitmproxy/pull/7963), @Julien00859)
+- Fix event loop leak when running tests
+  ([#7982](https://github.com/mitmproxy/mitmproxy/pull/7982), @DNEGEL3125)
 
 ## 15 October 2025: mitmproxy 12.2.0
 

mitmproxy/test/taddons.py

@@ -17,9 +17,11 @@ class context:
     """
 
     def __init__(self, *addons, options=None, loadcore=True):
+        self.owns_loop = False
         try:
             loop = asyncio.get_running_loop()
         except RuntimeError:
+            self.owns_loop = True
             loop = asyncio.new_event_loop()
 
         options = options or mitmproxy.options.Options()
@@ -36,6 +38,9 @@ def __enter__(self):
         return self
 
     def __exit__(self, exc_type, exc_value, traceback):
+        if self.owns_loop and not self.master.event_loop.is_closed():
+            # Close the loop if we created it
+            self.master.event_loop.close()
         return False
 
     async def cycle(self, addon, f):