invoke.context.Context is giving an odd error for missing positional argument

Question

I am trying to change directories in my python program within a context manager. using invoke.context.Context seems like the proper way to do it, got from the Fabric documentation and using a regular with os.chdir will not work.

However, when I try to do something such as

from invoke import Context

with Context.cd("/etc"):
    subprocess.run(["ls"])

I get an error back that says:

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-2-40b28af3213a> in <module>
----> 1 with Context.cd("/etc"):
      2     subprocess.run(["ls"])
      3

~/miniconda3/envs/python3/lib/python3.7/contextlib.py in helper(*args, **kwds)
    237     @wraps(func)
    238     def helper(*args, **kwds):
--> 239         return _GeneratorContextManager(func, args, kwds)
    240     return helper
    241

~/miniconda3/envs/python3/lib/python3.7/contextlib.py in __init__(self, func, args, kwds)
     80
     81     def __init__(self, func, args, kwds):
---> 82         self.gen = func(*args, **kwds)
     83         self.func, self.args, self.kwds = func, args, kwds
     84         # Issue 19330: ensure context manager instances have good docstrings

TypeError: cd() missing 1 required positional argument: 'path'

The documentation makes this seem correct ( http://docs.pyinvoke.org/en/latest/api/context.html#invoke.context.Context ), but i'm a little lost.

Any advice is helpful.

Answer 1

Looking at the documentation, it seems like you're supposed to create your own instance of Context , instead of using the Context class directly.

They also use the run() method on the Context instance instead of subprocess.run() .

Try this:

from invoke import Context

c = Context()
with c.cd("/etc"):
    c.run("ls")