Modern Python Projects Transcripts
Chapter: Testing code
Lecture: Testing code examples in the documentation
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One of the things that we usually forget to keep up to date is the documentation
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mostly because we don't have a tool that will tell us when it's outdated and it's no longer valid. pytest can solve part of this problem.
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If you put some code examples in your documentation, it can evaluate them and tell you when they are no longer working. Take a look at this function.
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We have a documentation that specifies how to use it, but actually the documentation is incorrect.
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But if we run pytest with --doctest-modules, parameter, it will check for parts of your documentations,
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starting with this triple right angle bracket(>>>). If it finds any line like that, pytest will treat the following text as Python code,
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and it will check that the result of this code is equal to the next line in the documentation. If it's not,
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it will report an error. So let's give it a try. And as you can see, pytest is complaining that there is a problem with docstring
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of add_two_numbers function. It was expecting 5, because here was specified 5. But actually the result of adding two numbers was 4.
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So that's a pretty cool way to test that code examples in your documentation are upto date.