There are state transitions start/done/suspend/resume and two additional
operations snap/writeorg.
Previously it was not well defined in what order they can be called, and
which operations are idempotent.
Formalize this and enforce using assert checks with informative error
messages if they fail (rather than random AttributeErrors).
Make it easier to read the file in progression, and avoid forward
references for upcoming type annotations.
There is one cycle, CaptureManager <-> CaptureFixture, which is hard to
untangle.
(This commit should be added to `.gitblameignore`).
This is already done in pytest_runtest_logstart, so the fspath is
already guaranteed to have been printed (for xdist, it is disabled
anyway).
write_fspath_result is mildly expensive so it is worth avoiding calling
it twice.
The `FDCapture`/`FDCaptureBinary` classes, used by `capfd`/`capfdbinary`
fixtures and the `--capture=fd` option (set by default), redirect FDs
1/2 (stdout/stderr) to a temporary file. To do this, they need to save
the old file by duplicating the FD before redirecting it, to be restored
once finished.
Previously, if this duplicating (`os.dup()`) failed, most likely due to
that FD being invalid, the FD redirection would silently not be done. The
FD capturing also performs python-level redirection (monkeypatching
`sys.stdout`/`sys.stderr`) which would still be done, but direct writes
to the FDs would fail.
This is not great. If pytest is run with `--capture=fd`, or a test is
using `capfd`, it expects writes to the FD to work and be captured,
regardless of external circumstances.
So, instead of disabling FD capturing, keep the redirection to a
temporary file, just don't restore it after closing, because there is
nothing to restore to.
This makes a difference for e.g. pytest-xdist:
Before:
```
--dist=distmode set mode for distributing tests to exec environments. each: …
available environment. loadscope: …
grouped by file to any available environment. (default) no: …
```
After:
```
--dist=distmode set mode for distributing tests to exec environments.
each: send each test to all available environments.
load: load balance by sending any pending test to any available environment.
…
(default) no: run tests inprocess, don't distribute.
```
This might also result in unexpected changes (hard wrapping), when line
endings where used unintentionally, e.g. with:
```
help="""
some long
help text
"""
```
But the benefits from that are worth it, and it is easy to fix, as will
be done for the internal `assertmode` option.
Katarzyna Król
Ran Benita
Anthony Sottile
Florian Dahlitz
Ronny Pfannschmidt
symonk
Claire Cecil
Bruno Oliveira
mcsitter
Daniel Hahler