[Python-Dev] unittest missing assertNotRaises (original) (raw)

Terry Reedy tjreedy at udel.edu
Tue Sep 27 22:06:22 CEST 2011

On 9/27/2011 2:46 PM, Wilfred Hughes wrote:

Hi folks

I wasn't sure if this warranted a bug in the tracker, so I thought I'd raise it here first. unittest has assertIn, assertNotIn, assertEqual, assertNotEqual and so

These all test possible specification conditions and sensible test conditions. For instance -1 and particularly 3 should not be in range(3). Including 3 is a realistic possible error. If you partition a set into subsets < x and > x, x should not be in either, but an easy mistake would put it in either or both.

Is there any particular motivation for not putting it in?

You have 'motivation' backwards. There are an infinity of things we could add. We need a positive, substantial reason with real use cases to add something.

An expression should return a particular value or return a particular expression. If it returns a value, testing that it is the correct value eliminates all exceptions. And testing for an expected exception eliminates all others. If there is an occasional needed for the proposal, one can write the same code you did, but with the possibility of excluding more than one exception. So I do not see any need for the proposal.

-- Terry Jan Reedy

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