bug#22145: 25.0.50; tramp and auto-revert tests hang on OS X

[Michael Albinus]

John Wiegley <jwiegley@gmail.com> writes:

>>>>>> Michael Albinus <michael.albinus@gmx.de> writes:
>
>> Given, that the last problems related to OS X have been solved by commit
>> df441b362c25c4ad59ea3d83137328d0d4098eaf, I believe we could close this bug.
>> Do you agree?
>
> OK, if you think this is a Nix bug and not an Emacs bug, then I'll take
> responsibility from here for the Nix fix and you can close this issue.

Done. However, I haven't said it is a Nix *bug*. I believe it is rather
a problem with the Nix *environment*.

IIRC, the problem was something like this on hydra.nixos.org years ago:

Tramp needs several programs in $PATH to run correctly. Usually, they are
found on every machine.

Nix does not offer them in general, because they are also tested in the
Nix environment, as part of coreutils or so. Therefore, they could be
found only by the user's local $PATH, which is set by Nix accordingly.

In order to fix this, tramp-tests.el checks whether we are in a Nix
environment (when (getenv "NIX_STORE"), and adds the local $PATH
settings then. Maybe this test does not work on your machine, and
$NIX_STORE isn't set? Then you need to test something else.

You could also add the local $PATH to Tramp's setting mandatory. Just
remove the check (getenv "NIX_STORE"). When it works, we know that this
is your problem (the same I have had years ago), and we must find a
better check for determining a Nix environment.

I do *not* want to add local $PATH settings in general for the tests,
because this would make the test indeterminable.

> Thanks for helping me debug this!

HTH. Best regards, Michael.