[Tutor] Testing a method in a class with nosetests

[Steven D'Aprano]

On 22/04/13 10:49, Alex Baker wrote:
> Hello,
> I've been lurking tutor for the last couple months and have quite enjoyed it!


Welcome, and congratulations on your first post! Unfortunately I have to start with a complaint :-( but it's NOT because you failed to post plain text, since you actually did.

When starting a new thread, please create a new, blank email, don't reply to an existing email. Especially not when that email is a digest containing four complete emails completely unrelated to your post! The end result is that at the bottom of your post is a copy of a complete digest, nearly 200 lines worth of unrelated, irrelevant stuff. (And we're lucky it was only 200 lines, during a busy week, digests could potentially be thousands of lines!) And then you compounded it by replying to the first email, and so ended up with those 200 lines quoted TWICE.


> I'm having a problem testing a method using nosetests. The assignment (Learn Python the Hard Way) asks that I write tests for a package using assert_equal and assert_raises. I've conquered the assert_equals but I'm having issues with assert_raises. I can't figure out how am I supposed to test a method in a class with an __init__. I understand the assert_raises works assert_raises("ERROR", callable, parameters), and the parameters get sent to nosetests, but because of the __init__ I have no parameters to send.


Unfortunately, I'm not familiar with nose, and so I'm guessing, but I would say replace this call:


     assert_raises("ParserError", _test_words("will fail"))

with this:

     assert_raises("ParserError", _test_words, "will fail")

or possibly this:

     assert_raises("ParserError", _test_words, ["will fail"])



I expect that the first version fails because the call to _test_words() function raises an exception before nose gets to handle it. This is why assert_raises takes a function argument, followed by its argument.




-- 
Steven