You can use the tmpdir function argument which will provide a temporary directory unique to the test invocation, created in the base temporary directory.
tmpdir is a py.path.local object which offers os.path methods and more. Here is an example test usage:
# content of test_tmpdir.py
import os
def test_create_file(tmpdir):
p = tmpdir.mkdir("sub").join("hello.txt")
p.write("content")
assert p.read() == "content"
assert len(tmpdir.listdir()) == 1
assert 0
Running this would result in a passed test except for the last assert 0 line which we use to look at values:
$ py.test test_tmpdir.py
=========================== test session starts ============================
platform linux -- Python 3.4.0 -- py-1.4.26 -- pytest-2.7.0
rootdir: /tmp/doc-exec-129, inifile:
collected 1 items
test_tmpdir.py F
================================= FAILURES =================================
_____________________________ test_create_file _____________________________
tmpdir = local('/tmp/pytest-216/test_create_file0')
def test_create_file(tmpdir):
p = tmpdir.mkdir("sub").join("hello.txt")
p.write("content")
assert p.read() == "content"
assert len(tmpdir.listdir()) == 1
> assert 0
E assert 0
test_tmpdir.py:7: AssertionError
========================= 1 failed in 0.01 seconds =========================
Temporary directories are by default created as sub-directories of the system temporary directory. The base name will be pytest-NUM where NUM will be incremented with each test run. Moreover, entries older than 3 temporary directories will be removed.
You can override the default temporary directory setting like this:
py.test --basetemp=mydir
When distributing tests on the local machine, pytest takes care to configure a basetemp directory for the sub processes such that all temporary data lands below a single per-test run basetemp directory.