
Temporary directories and files
*******************************


The 'tmpdir' test function argument
===================================

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 linux2 -- Python 2.7.3 -- pytest-2.3.5
   collected 1 items

   test_tmpdir.py F

   ================================= FAILURES =================================
   _____________________________ test_create_file _____________________________

   tmpdir = local('/tmp/pytest-323/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 0.02 seconds =========================


The default base temporary directory
====================================

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, "py.test" 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.
