test: stabilize proxy tests

[jpnurmi]

Proxy-related tests have been failing quite often lately

• https://github.com/getsentry/sentry-native/actions/runs/26021133925/job/76482722733
• https://github.com/getsentry/sentry-native/actions/runs/26445239447/job/77855071695
• ...

Replace the hardcoded 0.5s sleep with a wait loop that gives mitmdump up to 10s to get a response from the mock server. This should help in busy CI environments where runners may be under load and processes can be delayed.

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cursor]

Reader thread and communicate() race on same stdout pipe

Medium Severity

The reader thread reads from proxy_process.stdout via readline(), and then proxy_process.communicate() is called on the same pipe. communicate() internally calls self.stdout.read() followed by self.stdout.close(). If communicate() acquires the BufferedReader lock before the reader thread finishes its loop, it will close the file object, causing the thread's next readline() to raise ValueError. This also means the two readers compete for pipe data — the thread never gets joined, so there's no guarantee it's finished before "".join(stdout) on line 165 is evaluated. The fix would be to avoid calling communicate() and instead use proxy_process.wait() + reader.join() to collect output solely through the reader thread.

Additional Locations (1)

• tests/proxy.py#L143-L151

 

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