Function test_capture_fd_stale_reference

tests/test_testing.py:574–596

capture='fd' captures writes from stale stdout references (issue #2874). Simulates ``from sys import stdout`` at import time, which grabs the real stdout connected to fd 1. The stale object's underlying FileIO uses fd 1, so redirecting fd 1 captures its writes.

()

@needs_fd_capture
def test_capture_fd_stale_reference():
    class="st">"""capture=&class="cm">#x27;fd' captures writes from stale stdout references (issue #2874).

    Simulates ``from sys import stdout`` at import time, which grabs
    the real stdout connected to fd 1.  The stale object&class="cm">#x27;s underlying
    FileIO uses fd 1, so redirecting fd 1 captures its writes.
    class="st">"""
    class="cm"># open(1, ..., closefd=False) creates a writer whose underlying
    class="cm"># FileIO uses fd 1 directly. This mirrors the real scenario:
    class="cm"># the original sys.stdout is a TextIOWrapper -> BufferedWriter ->
    class="cm"># FileIO(fd=1).
    stale_stdout = open(1, class="st">"w", closefd=False)  class="cm"># noqa: SIM115

    @click.command()
    def cli():
        stale_stdout.write(class="st">"stale write\n")
        stale_stdout.flush()
        click.echo(class="st">"normal write")

    runner = CliRunner(capture=class="st">"fd")
    result = runner.invoke(cli)
    assert class="st">"normal write" in result.stdout
    assert class="st">"stale write" in result.stdout


@needs_fd_capture