[py-dev] Test directories for py.test

[Carl Friedrich Bolz]

Hi Tom!

Tom Harris wrote:
 > I like to have my tests in a subdirectory for a project, so directory
 > 'foo' would have a subdirectory 'test'. The tests in 'test' should be
 > able to load module foo.py in it's parent directory, with a
 > sys.path.insert(0, '..'). That's the way I did it with unittest anyway.
 > Example below fails unless I insert a '.' instead of '..' into sys.path.
 >
 > file 'foo/foo.py':
 >     def a(): return 1
 >
 > file 'foo/test/test_foo.py':
 >     import sys
 >     sys.path.insert(0, '..')
 >     import foo
 >
 >     def test_1():
 >        assert foo.a() == 1
 >
 > Now I'm quite happy to type import sys; sys.path.insert(0, '.') at the
 > head of all my test files, but am I missing something?

Since this is quite a common problem, There is a built-in solution in
py.test :-). The idea is the following: py.test inserts a certain path into
sys.path. Which path that is, is determined by walking up the
directories starting from the test dir until it finds a directory that
does not have an __init__.py file. So what you could do:

  file 'foo/__init__.py':
      # empty or whatever

  file 'foo/bar.py':
      def a(): return 1

   file 'foo/test/__init__.py':
      # empty or whatever

   file 'foo/test/test_bar.py':
       from foo import bar

       def test_a():
           assert bar.a() == 1


This allows you to have a deeper directory hierarchy and always the
right directory is inserted (as long as you have __init__.py files
everywhere but in the dir above your project).

Cheers,

Carl Friedrich