Getting Started with Testing in Python
Testing code is always wanted as a good habit. when you are working on a project, It’s really a good idea to check that every single unit/program is working perfectly. There is a lot of modules to test code in python. In this article, I’m going to share some basic with coding examples to getting started with python unit testing.
Automated vs. Manual Testing
Testing is an integral part of any successful software project. Software Testing is categorized into two parts namely Automation Testing and Manual Testing.
Manual Testing
Manual Testing is the process of testing the Software manually to find the defects before software goes live. This testing process is performed by a Quality Assurance engineer. In this process, testers execute test cases and generate reports manually without using any automation testing tools.
There is some kind of manual testing processes used by the testers.
- Black Box Testing
- White Box Testing
- Unit Testing
- System Testing
- Integration Testing
- Acceptance Testing
I’m not going deep in each type of Manual Testing on this basic learning. I will try to explain these types in my next article.
Automation Testing
Automation Testing is the process of testing the software using an automation tool to find the defects. In this process, executing test scripts and generating reports are performed automatically. Some automation tools are:
- Selenium
- LoadRunner
- SilkTest
- IBM Functional Tester
This comparison doesn't mean that you can choose one over the other. In the software industry, both of them are used sequentially. There is still a lot to know about Automation and Manual Testing.
Unit Testing vs. Integration Testing
When you are working on a team, you may contribute a small part of the software/project. The combined works become a successful project. When you write a simple function and test that code is working fine, then this type of test is called a Unit test. When all of the modules are integrated and then testing is required to check that everything is working as expected, that’s called Integration Testing. So, a unit testing is to identify that a small component is working or not whereas integrated testing is to identify that component operates with each other components on the application.
Unit test:
- identify a small piece of code is working as expected or not
- checks a single component of the application/module
- It comes under the white box testing type
- test each unit separately and ensure that each unit is working as expected
Integration Testing
- identify different modules are working as expected
- It checks the overall flow of the application
- comes under both white box and black box
- It’s performed after unit testing
In the 1st part, I have explained some basics of software testing and its purposes. In the 2nd part, I am giving some coding examples basis on unit testing in python.
In python programming, there are many test runners available. unittest
is one of them which one is built into python standard library. Some other test runners are:
doctest
pytest
unittest
unittest
is a python built-in standard library. unittest
contains both a testing framework and a test runner. To write and execute tests, it has some requirements. whiches are
- You need to put your test cases inside a class as methods
- You have to use assertion methods in the
unittest
class
unittest
assertion methodsTo execute a test you have to:
- import
unittest
library - create a class that inherits from
unittest.TestCase
- define test method with
self
as an argument - use
self.assertion
series to perform test execution - To generates the test results run
unittest.main()
inside the main function
That’s all, you will get OK
if there is no error, see the below example.
Doctest
The doctest
also a python built-in library. This module searches for pieces of text that look like interactive Python sessions in docstrings and then execute those sessions to verify that they work exactly as shown.
Doctests
have a different use case than proper unit tests: they are usually less detailed and don’t catch special cases or obscure regression bugs. They are useful as expressive documentation of the main use cases of a module and its components. However, doctests
should run automatically each time the full test suite runs.
A simple doctest
in a function
While running this code, doctest
will run and complain if the given description doesn't work as expected.
pytest
pytest
is an external tool for testing in python. It has some advantages compared to unittest
. Since it is an external tool, so you have to install it first in your python interpreter. To install pytest
run the following command:
pip install pytest
following code to understand how it works:
Run the following command in your project terminal:
py.test pytest.py
You will get results like the above image.
We see that, pytest
doesn’t need any TestClass, we can use simply assert
to check test cases and execute the test cases directly from the terminal to generate reports.
You can use whatever you like and depending on your requirements. You can share with us which python module you are using currently.
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