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On the other hand, as expected, the call to the sum function is shown as failed . As before, both the location and the nature of the failure is explained.
As mentioned earlier , in addition to putting tests in separate text files, you can also embed tests in docstrings.
As shown in the earlier module titled Itse1359-1270-Functions , and described more fully in What is a Docstring? , a docstring is a string literal that occurs as the first statement in a module, function, class, or method definition. A docstring is surrounded bytriple quotes.
This example will perform a test on a simple function named sum in a module named Py1359_1720_03.py as shown in Listing 6 .
| Listing 6 . Contents of the file named Py1359_1720_03.py. |
|---|
""">>>sum(2,3)
6"""
def sum(parA,parB):return parA + parB
if __name__ == "__main__":import doctest
doctest.testmod() |
Listing 6 is an update of the earlier module shown in Listing 3 . Test code was embedded in the docstring at the beginning of Listing 6 .
In addition, a special if statement was added at the end of Listing 6 that calls the testmod function of the doctest module. (See the earlier comment regarding the testmod function and the command line shortcut.)
According to The Python Standard Library -- 26.2.1. Simple Usage: Checking Examples in Docstrings , if you include this code at the end of a module, running the module as a script will cause tests that are embedded in docstrings to be executed.
Detailed information on the various options of the testmod function are provided at The Python Standard Library -- 26.2.4. Basic API .
The batch file used to execute the test is shown in Listing 7 .
| Listing 7 . Contents of the batch file named Py1359_1720_03.bat. |
|---|
echo off
rem set the pathpath=%path%;"C:\Program Files (x86)\Python34"
rem perform the testpython Py1359_1720_03.py -v
pause |
In this case there was no separate test file. Instead, the python command in Listing 7 executed the module named Py1359_1720_03.py as a script triggering the test to be run as described above .
The -v switch in Listing 7 causes the verbose version of the output to be produced as shown in Figure 4 . Once again, I set the test up in such a way as to cause it to fail for purposes of illustration.
| Figure 4 . Output produced by the test embedded in the docstring. |
|---|
Trying:
sum(2,3)Expecting:
6**********************************************************************
File "Py1359_1720_03.py", line 4, in __main__Failed example:
sum(2,3)Expected:
6Got:
51 items had no tests:
__main__.sum**********************************************************************
1 items had failures:1 of 1 in __main__
1 tests in 2 items.0 passed and 1 failed.
***Test Failed*** 1 failures. |
I encourage you to copy the code provided in this module. Execute the code and confirm that you get the same results. Experiment with the code,making changes, and observing the results of your changes. Make certain that you can explain why your changes behave as they do.
Now that you know some of the mechanics of using doctest , you should study the next module in the collection titled Itse1359-1720r-Review . In addition, you should study some of the many articles andtutorials that are freely available on the web that provide insight into the use of doctest for unit testing. Links to a few of those documents are provided below. You canfind many more with a simple web search.
This section contains a variety of miscellaneous information.
Financial : Although the Connexions site makes it possible for you to download a PDF file for thismodule at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, you should beaware that some of the HTML elements in this module may not translate well into PDF.
I also want you to know that, I receive no financial compensation from the Connexions website even if you purchase the PDF version of the module.
In the past, unknown individuals have copied my modules from cnx.org, converted them to Kindle books, and placed them for sale on Amazon.com showing me as the author. Ineither receive compensation for those sales nor do I know who does receive compensation. If you purchase such a book, please beaware that it is a copy of a module that is freely available on cnx.org and that it was made and published withoutmy prior knowledge.
Affiliation : I am a professor of Computer Information Technology at Austin Community College in Austin, TX.
-end-
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