How to patch OS.mkdir with Mock?

Question

I am trying to unit test using the Mock module with pytest. I want `os.path.isdir()` to return False, and `os.mkdir()` not to run; I just want to verify the correct arguments are passed to it. I think you only need to look at `set_path` method My app: ``` import pytumblr, os, sys, prowlpy, json, collections from urllib2 import urlopen from time import sleep from apiclient.discovery import build class Site(object): """A generic site.""" def __init__(self, user): self.user = user def set_path(self): if os.path.isdir(self.user_dir): # if user dir already exists print "**Directory already exists: ", self.user_dir else: os.mkdir(self.user_dir) # else create user dir print "Created Directory: ", self.user_dir class Tumblr(Site): """A tumblr blog.""" type = "tumblr" type_dir = os.path.join(os.getcwd(), type) def __init__(self, user): super(Tumblr, self).__init__(user) self.user_dir = os.path.join(Tumblr.type_dir, self.user) ``` My test always fails as shown below here: ``` import tumblrip_ne…

Accepted Answer

I fixed it in the following way:

```
@mock.patch('tumblrip_new.os.path')
@mock.patch('tumblrip_new.os')
def test_create_new_user_dir(self, mock_os, mock_path):
    """Creates a directory if one does not exist."""
    t = tum.Tumblr("username")
    # directory does not exist:
    mock_path.isdir.return_value=False
    t.set_path()
    mock_os.mkdir.assert_called_with(t.user_dir)
```

How to patch OS.mkdir with Mock?

Solution

Problem