Create a context manager for changing current working directory

[bsanders]

Hello,

I have a use-case which doesn't quite work in testinfra as it stands.

host.run() on a local host eventually calls subprocess.run(). That's great, but I noticed it doesn't pass **kwargs. The fix is trivial, but I've no idea:

• if this implementation of the fix is acceptable
• what it breaks outside my use case.

I added a test, which fails in docker (see below). I haven't started digging in yet because I thought I'd check first if this whole idea was a non-starter?

test/test_modules.py::test_command_execution_in_chdir[docker://debian_stretch] 
[gw1] [ 93%] FAILED test/test_modules.py::test_command_execution_in_chdir[docker://debian_stretch] 

    def test_command_execution_in_chdir(host):
>       assert host.run("pwd", cwd='/tmp').stdout.strip() == '/tmp'
E       AssertionError: assert '/' == '/tmp'
E         - /
E         + /tmp

[philpep]

Hi, thanks for contributing !

I'm not sure all arguments of subprocess are useful here, but cwd definitively is. But the way you've implemented it only works with "local" backend. What about adding a new context manager cwd for this, which could enable it for all modules ? For instance:

with host.cwd('/opt/local/app'):
    assert host.file('./myapp').mode == 755
    assert host.run('./myapp --version') == '1.2.3'

Under the hood, all remote commands would change directory before running the command. I think this code will be similar to host.sudo() context manager. What do you think ?

[bsanders]

@philpep

That sounds reasonable. I'll change the title to reflect that and take a look at an implementation.

This is the file you're suggesting as a model, yes? testinfra/modules/sudo.py