[SciPy-dev] tests, relative import: what's best ?

[David Cournapeau]

Hi,

    I have a question regarding tests and import in numpy/scipy in 
general. When implementing tests, the package to be tested has to be 
imported, and there are two possibilities on how to do it (both are used 
in scipy). Taking an hypothetical package foo in scipy as an example:

    1 : using set_package_path /restore_path facilities of 
numpy.testing, and do a "relative" import

set_package_path()
from foo import bar
restore_path()

This means that you can test the package foo without building the whole 
scipy source tree. This is for example used in scipy.linalg tests. It 
also correspond to DISTUTILS.txt doc in numpy/doc.

    2 : using set_package_path / restore_path facilities, and do a 
"absolute" import:

set_package_path()
from scipy.foo import bar
restore_path()

In this case, I don't understand why set_package_path is used ? And 
also, this means that you cannot test the subpackage by itself, you need 
to install the whole scipy tree. This is for example used in 
scipy.signal tests.

Are there any advantages to 2 ? If not, would it be a good idea to 
convert every package to convention 1 ?

cheers,

David