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There are at least two different ways to use doctest :
A simple example of each approach will be provided and explained in this module.
Figure 1 shows a simple interactive session run on the Python interactive command line interface.
| Figure 1 . Simple interactive session. |
|---|
>>>2 + 3
5>>> |
If you have forgotten what the text in Figure 1 means, see the earlier module titled Itse1359-1010-Getting Started .
This first example is provided solely to show how doctest works. It is not intended to be useful otherwise.
Listing 1 shows the contents of a test file named Py1359_1720_01.txt .
| Listing 1 . Contents of the test file named Py1359_1720_01.txt. |
|---|
>>>2 + 3
6 |
Note that the contents of the test file mirror the input and the output of the interactive session shown in Figure 1 except that the result of performing the computation was purposely specified incorrectly as 6 instead of 5. (When you create a doctest test file, you must specify the required output as shown in Listing 1 .)
Note that the doctest process is very picky regarding file names. Some file names that are valid for the operating system may not work when using doctest . However, if you restrict your file names to names that would be valid for variables, you should be okay.
Listing 2 shows the contents of a Windows batch file named Py1359_1720_01.bat that I used to perform the test. Although not a requirement, the use of such a batch file makes it convenient to performthe test more than once with a minimal typing effort.
| Listing 2 . Contents of the file named Py1359_1720_01.bat. |
|---|
echo off
rem set the pathpath=%path%;"C:\Program Files (x86)\Python34"
rem perform the testpython -m doctest Py1359_1720_01.txt
pause |
(Some of the text in Listing 2 is peculiar to my machine. You can ignore the text shown in Listing 2 down to the command that begins with the word python .)
The third command that begins with the word python in Listing 2 executes the Python doctest module as a script and passes the name of the test file as a command-lineargument to the module.
According to Python v3.1.5 documentation -- Python Setup and Usage , "When called with -m module-name, the given module is located on the Python module path and executed as a script."
The syntax shown for the python command in Listing 2 is a command line shortcut for calling the testmod() function in the doctest module. (You will see more on this later.)
The execution of the python command in Listing 2 produced the command line output shown in Figure 2 .
| Figure 2 . Output produced by the test filenamed Py1359_1720_01.txt. |
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**********************************************************************
File "Py1359_1720_01.txt", line 2, in Py1359_1720_01.txtFailed example:
2 + 3Expected:
6Got:
5**********************************************************************
1 items had failures:1 of 1 in Py1359_1720_01.txt
***Test Failed*** 1 failures. |
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