Where to put tests for subpackages in python?

When a python module has multiple subpackages, where should tests for features in those subpackages be placed?

I can see two ways it could be done:

• Create a separate test folder in each subpackage and place its tests there.
• Duplicate the package hierarchy in the top-level test folder, placing the tests for each subpackage in the corresponding folder.

However it's not clear which option should be preferred.

For a package foo arranged like this:

foo/
  __init__.py
  bar.py
  baz/
    __init__.py
    baz.py

Do I put the tests here?

foo/
  __init__.py
  bar.py
  baz/
    __init__.py
    baz.py
  test/
    __init__.py
    test_bar.py
    baz/
      __init__.py
      test_baz.py

Or here?

foo/
  __init__.py
  bar.py
  baz/
    __init__.py
    baz.py
    test/
      __init__.py
      test_baz.py
  test/
    __init__.py
    test_bar.py