Mocking `from foo import *` functions

[Rob Williscroft]

 wrote in news:a9ed10ff-d907-46f0-8c6a-
c3d95579a5ab at k1g2000prb.googlegroups.com in comp.lang.python:

> To answer to Rob: yeah, sure that would work, but I always thought

Just to note: you're answering a question about testing, but I 
answered how to alter the alerter module *for* testing. given it
was the import * that was causing the OP the problem, I tried to
address that.

> mocking the imported function didn't feel right. The test then depends
> on the import method of the tested module. If you later change your
> mind and decide to use "import sender" and then "sender.sendEmails()",
> you have to change your test code.

You have to add:

  import sender
  sender.sendEmails = mock_sendEmails

to your test script.

Note that doing the above *before* any other module imports
from sender, will be sufficient in *any* case, though it won't 
help if the tested code calls reload( sender ).

No need to scan every imported module for the mocked function.  

It also handles the case where other code imports the sender
module and calls sendEmails().

For additional robustness the above can be changed to:

  ## assert sender module hasn't been imported elsewhere yet
  
  import sys
  assert 'sender' not in sys.modules  

  import sender
  sender.sendEmails = mock_sendEmails

Rob.
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