How to use the doctest module for document testing in Python 2.x

How to use the doctest module for document testing in Python 2.x

Introduction:
In Python, we can test whether the code meets the expected output by writing documentation tests. Among them, the doctest module is part of the Python standard library and can be used to write and execute document tests.

Documentation testing is a method of embedding code examples into the docstrings of functions and classes. By executing the examples in the docstring and comparing with the expected output, we can verify the correctness of the code.

The following will introduce how to use the doctest module and give some sample codes.

Usage:

1. Import the doctest module:
   Before you start using doctest for document testing, you need to import the doctest module first. The imported statement looks like this:

   import doctest

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2. Writing test cases:
   Write test cases in the docstring of the function or class. Each test case consists of two parts: one part is the sample code, and the other part is the expected output of the execution of the sample code. Sample code usually starts with ">>>" and the output is expected to start with the following lines. An example looks like this:

   def add(a, b):
       """
       Function to add two numbers.
   
       Examples:
       >>> add(2, 3)
       5
       >>> add(0, 0)
       0
       """
       return a + b

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3. Run doctest:
   Add the following code at the end of the script to run doctest:

   if __name__ == '__main__':
       doctest.testmod()

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   Then execute the script and doctest will verify the example Check whether the output of the code is consistent with the expected output and output the test results. If the test passes, nothing will be output. Otherwise, an error message will be output.

Sample code:
The following is an example of using doctest for document testing:

import doctest

def add(a, b):
   """
   Function to add two numbers.

   Examples:
   >>> add(2, 3)
   5
   >>> add(0, 0)
   0
   """
   return a + b

if __name__ == '__main__':
   doctest.testmod()

After executing the script, if the test passes, nothing will be output. . If the test fails, an error message will be output. In this case, the sample code all passes the test.

Summary:
doctest is a convenient module for testing whether a function or class works as expected. By writing sample code and expected output in docstrings, we can easily test and catch problems in a timely manner. I hope this article helps you understand and use the doctest module.

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