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There are at least two different ways to use doctest :

  1. You can write the test code in a separate text file and use that file to perform the testing.
  2. You can embed the test code in one or more docstrings in a module and cause the test code to be executed each time you execute the module as ascript.

A simple example of each approach will be provided and explained in this module.

Discussion and sample code

An interactive session

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 .

An automated interactive session

This first example is provided solely to show how doctest works. It is not intended to be useful otherwise.

The test file named Py1359_1720_01

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.

The batch the named Py1359_1720_01

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 output

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.
********************************************************************** 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.

Questions & Answers

how to know photocatalytic properties of tio2 nanoparticles...what to do now
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Mostly, they use nano carbon for electronics and for materials to be strengthened.
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Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
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Graphene has a hexagonal structure
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I start with an easy one. carbon nanotubes woven into a long filament like a string
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what is nanomaterials​ and their applications of sensors.
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what is system testing?
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Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
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In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
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Source:  OpenStax, Itse 1359 introduction to scripting languages: python. OpenStax CNX. Jan 22, 2016 Download for free at https://legacy.cnx.org/content/col11713/1.32
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