Testing exception messages #1080

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1. cmccandless

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   on Oct 30, 2017
2. cmccandless commented on Oct 30, 2017

   

   cmccandless

   on Oct 30, 2017

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   Worth noting is that we have a precedent for methods that differ between Python2 and Python3.
3. N-Parsons commented on Nov 5, 2017

   

   N-Parsons

   on Nov 5, 2017

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   Personally I'm not a great fan of requiring particular error messages to be raised by the user. Meaningful messages are great, but exact wording just feels like unnecessary copy-and-pasting to me, and doesn't give the learner the freedom to think about and express what the meaning/source of the error is. This would particularly frustrate me if I thought that the error message was imprecise or I wanted to also display key values.

   If we want to test whether people are including messages with their exceptions, we can do a regex for r".+", which would just test that there is something there, and then trust that people will choose to implement something meaningful. I actually quite like this approach, because it actively encourages something which is good practice, without constraining the learner.
4. ilya-khadykin commented on Nov 7, 2017

   

   ilya-khadykin

   on Nov 7, 2017

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   Usually, there are two issues:

   1. ValueError (or others for that matter) is raised without any meaningful error message which makes the code less readable and hard to use
   2. throwing exceptions of an inappropriate type (it's especially true for Java but it also true for Python as well in some cases)

   If we address this two issues this will be a good enough.
5. cmccandless commented on Nov 7, 2017

   

   cmccandless

   on Nov 7, 2017

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   ValueError (or others for that matter) is raised without any meaningful error message which makes the code less readable and hard to use

   Sounds like @N-Parsons 's solution of using r".+" would be adequate for this.

   throwing exceptions of an inappropriate type (it's especially true for Java but it also true for Python as well in some cases)

   This is situational; I don't know that there's a good standardized way to handle this other than please review.
6. N-Parsons commented on Nov 8, 2017

   

   N-Parsons

   on Nov 8, 2017

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   If we do implement checks for the presence of error messages, I think we should definitely add something about it to the README insert so that it's clear that we're expecting them (and to encourage people to make them meaningful).

   Exception types are controlled by the test-suite, so there's not really much problem on the learner side, but we should try to have some consistency between the test-suites. We could create something along the lines of the Choosing Exceptions to Raise doc pandas has to give everyone something to refer to.

   👍React with 👍2Reacted by Corey McCandless and Ilya Khadykin
7. N-Parsons

   added 2 commits that reference this issue on Nov 18, 2017

   Implement checks for messages being raised with exceptions

   ...

   This issue will close once commit ab1acd7 is merged into the 'master' branch.

   ab1acd7

   Implement checks for messages being raised with exceptions

   ...

   This issue will close once commit d15bca4 is merged into the 'master' branch.

   d15bca4
8. cmccandless

   closed this as completedin #1113on Dec 12, 2017
9. cmccandless

   added a commit that references this issue on Dec 12, 2017

   Implement checks for raising messages with exceptions (#1113)

   ...

   This issue will close once commit f53e2ef is merged into the 'main' branch.

   f53e2ef
10. cmccandless commented on Nov 27, 2018

    

    cmccandless

    on Nov 27, 2018

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    For future record, here is the proper way to handle exception testing in this repository:

    class TestClass(unittest.TestCase):
    	def test_raises_exception(self):
            with self.assertRaisesWithMessage(ValueError):
                method_that_raises_ValueError()
    
        # Utility functions
        def setUp(self):
            try:
                self.assertRaisesRegex
            except AttributeError:
                self.assertRaisesRegex = self.assertRaisesRegexp
    
        def assertRaisesWithMessage(self, exception):
            return self.assertRaisesRegex(exception, r".+")

    Edit: if Python 2.7 is no longer supported, the above snippet may be simplified to the following:

    class TestClass(unittest.TestCase):
        def test_raises_exception(self):
            with self.assertRaisesWithMessage(ValueError):
                method_that_raises_ValueError()
    
        # Utility functions
        def assertRaisesWithMessage(self, exception):
            return self.assertRaisesRegex(exception, r".+")