Fix capteesys producing doubled output with --capture=no#14205
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Pierre-Sassoulas merged 5 commits intoMay 23, 2026
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When capteesys is used with -s (--capture=no), output was printed twice: once by TeeCaptureIO teeing to the original stream in real-time, and again by pop_outerr_to_orig() writing the buffered content back via writeorg() on close. Skip the writeorg() call when tee is enabled, since the output was already delivered live. Fixes pytest-dev#13784.
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RonnyPfannschmidt
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Feb 18, 2026
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Hey @worksbyfriday, it seems the CI isn't green anymore using latest main, would you mind looking into it, please ? |
Pierre-Sassoulas
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May 23, 2026
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Fixes #13784.
Summary
When
capteesysis used with-s(--capture=no), everyprint()call produces doubled output on the terminal.Root cause:
TeeCaptureIO.write()tees output to the original stream in real-time. OnCaptureFixture.close(),pop_outerr_to_orig()callswriteorg()which writes the same buffered content to the original stream a second time.With other capture modes (e.g.
--capture=fd), the "original stream" thatwriteorg()targets is the global capture's pipe — so the double write is absorbed correctly. With--capture=no, there is no global capture, sowriteorg()writes directly to the real terminal, producing the duplicate.Fix: When tee is enabled, use
readouterr()instead ofpop_outerr_to_orig()inclose(), since the output was already delivered live byTeeCaptureIO.Test plan
test_capteesys_no_double_output_with_capture_nothat verifies output appears exactly once when usingcapteesyswith-sTestCaptureFixturetests pass