[Biopython-dev] added requires_internet test

[Jeffrey Chang]

Hey all,

I've added a file requires_internet.py to Bio/Tests.  This is
basically a modules that's used to detect whether the internet is
available.  If it is, then nothing happens.  If it is not, then it
raises an ImportError.

This file is useful for the regression tests.  Add "import
requires_internet" to the top of each of the regression test files
(test_*).  This way, if the internet is available, then the tests run
normally.  Otherwise, the tests are skipped.

I've already added it to test_ais and test_HotRand.  Please add it to
other test files as appropriate.

Also, please give it a spin, and let me know if there are any bugs!

Thanks,
Jeff